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This paper examines the activation energy influence in third-grade nanoparticle flow model (TG-NPFM), which is nonlinear mixed convective flow over a spinning disk under the influence of heat sink/source as well as viscous dissipation by utilizing Bayesian Regulation Method with backpropagated Artificial Neural Networks (BRM-BPANN). Nonlinear thermal radiation is also involved in the considered flow dynamics to obtain the approximated numerical solutions. The nonlinear PDEs of TG-NPFM are then transformed into nonlinear ODEs by implementing the corresponding transformation. We solved these ODEs by Optimal Homotopy Analysis Method (OHAM) to explain the dataset used as a reference for BRM-BPANN for different scenarios of TG-NPFM. This reference dataset is then exported to MATLAB to compute the results. The outcomes of TG-NPFM are figured by adopting the procedures of testing, validation and training. Moreover, approximated solution is compared with standard solution and the efficacy examination of TG-NPFM is authenticated by the studies of MSE, error histogram and regression plots. These soft computation frameworks provide incentive to use an efficient and dependable alternative paradigm built on soft computing environments to solve problems by doing a descriptive analysis to mitigate the impacts of different physical features. It is a new implementation of intelligent computational system of artificial intelligence introduced by incorporating the solver BRM-BPANN for interpreting the TG-NPFM. The absolute error values lie between 10 − 8 to 10 − 5 , 10 − 1 0 to 10 − 5 , 10 − 8 to 10 − 4 , 10 − 9 to 10 − 3 , 10 − 9 to 10 − 5 , 10 − 9 to 10 − 3 , 10 − 9 to 10 − 3 and 10 − 9 to 10 − 3 , which show the reliability and accuracy of the technique. The convergence and precision of the algorithm can easily be seen through the results of performance, training state and fitness plot, along with the regression value of R = 1. [ABSTRACT FROM AUTHOR]

Analytical solutions for functionally graded (FG) rotating disks are limited due to the functional representation of the cross-sectional geometry, the density, and the modulus of elasticity which lead to a governing differental equation with variable coefficients. Analytical solutions for such disks are limited according to the functional form chosen for the variation of the property. Hence, analytical approximation approaches gain importance for such problems. In this study, two analytical approximation approaches are proposed for the analysis FG rotating disks. The methods used are the Improved Adomian decomposition method (IADM) and the optimal homotopy asymptotic method (OHAM). The resulting solution is an analytical solution in power series form. It is assumed that the disks considered are subjected to constant angular velocity. Material properties such as modulus of elasticity, density and yield strength are assumed to vary along the radial direction according to the power law function. Stresses are obtained for different values of the gradient parameters to investigate the effects of the parameters. Von Mises yield criterion is used to determine elastic limit angular velocities. The results from this study are in very good agreement with previous results available in the literature. In addition, it is observed that OHAM converges to results much faster than IADM. [ABSTRACT FROM AUTHOR]

In this paper, the impact of nanolayer which shows the relationship between the nanoparticle and pure fluid is investigated on the fluid transport and thermal transfer through a rotating system. The nanolayer shows the relationship between the nanoparticle and base liquid, signifying a higher thermal conductivity than the nanoparticle and lower conductivity than the base fluid. Also, the effect of larger nanoparticle size and volume on fluid thermal distribution is considered. The nanoparticle raises the fluid thermal conductivity with the aim of conserving thermal transfer during fluid transport, consequently saving energy. The mechanics of the fluid is developed using a higher‐order coupled system of nonlinear models, solved with the aid of the Homotopy perturbation method. Obtained results from the analysis show the impact of nanolayer expansion on thermal distribution increases boundary layer thickness. Also, the size of the nanoparticle when varied from 10 to 40 nm shows a heat transfer increase of 17.02% at the center of the disk. Particle size increase indicates temperature rise as nanolayer size encompassing the nanoparticle increases. Obtained results when compared against literature give good agreement. The study finds useful applications in coolant and lubricant processing amongst other practical applications. [ABSTRACT FROM AUTHOR]

A hybrid nanofluid is an amalgamation of two or more types of nanoparticles in a customary and possesses a variety of industrial applications. This exploration examines the blend of copper (Cu) and gold (Au), and engine oil as a hybrid nanofluid. The model considers the Hall current, Cattaneo–Christov (C-C) heat flux, thermal stratification, nonuniform heat source, and nonlinear thermal radiative effects for heat analysis. Ordinary differential equations (ODEs) are obtained through a similarity transformation scheme, and the model is visualized using a MATLAB function bvp4c. Graphs are presented to demonstrate the impact of various parameters on velocities and temperatures, and the wall drag coefficient and wall heat transfer rate are calculated and tabulated for both disks. The results show that a stronger Hall effect leads to a decrease in tangential velocity, while nonuniform heat sources increase fluid temperature. Thermal radiation and stratification have opposite effects on liquid temperature. It is interesting to note that for the radiation parameter at Rd = 0.5 , a higher heat transfer rate occurred at the lower disk, i.e., (N u 1 = − 3.63314) as compared to the upper disk (N u 2 = − 3.63324). Moreover, for the stratification parameter at S = 0.2 , it is observed that the heat transfer rate is lesser at the upper disk (N u 2 = − 3.64374) than at the lower disk (N u 1 = − 3.64274). Verification of the truthfulness of the proposed model is also included in the article. [ABSTRACT FROM AUTHOR]

This study examines Titania nanofluids that conduct electricity and are combined with various base fluids, focusing on various aspects. A magnetic field analyzes a continuous flow of nanofluid over a rotating disk that is positioned at an angle with a three-dimensional geometry assumption. The continuity, momentum, and energy balance equations are established, transformed using similarity variables, and solved through Akbari–Ganji Method (AGM) and Homotopy Perturbation Method (HPM) semi-analytical methods. The effects of several parameters, such as Magnetic parameter (M), Hall parameter (m), Porosity parameter (γ), Radiation parameter (Rd), and Thickness of liquid (δ), are examined through a graphical representation of state variables, including skin friction and Nusselt number. Additionally, the Response Surface Method (RSM) method has been utilized to simultaneously display the effects of porosity parameters and various factors across the disk. The findings showed that the magnetic, porosity, Hall, and thickness parameters had a significant impact on the behavior of the nanofluid. Specifically, the magnetic field had a strong influence on the velocity and temperature distribution of the fluid as it flowed over the rotating disk, while changes in porosity, Hall, and thickness parameters also affected these state variables. [ABSTRACT FROM AUTHOR]

Herein, a series of monometallic Ni‐, Co‐ and Zn‐MOFs and bimetallic NiCo‐, NiZn‐ and CoZn‐MOFs of formula M2(BDC)2DABCO and (M,M')2(BDC)2DABCO, respectively, (M, M'=metal) with the same pillar and layer linkers 1,4‐diazabicyclo[2.2.2]octane (DABCO) and benzene‐1,4‐dicarboxylate (BDC) were prepared through a fast microwave‐assisted thermal conversion synthesis method (MW) within only 12 min. In the bimetallic MOFs the ratio M:M' was 4 : 1. The mono‐ and bimetallic MOFs were selected to systematically explore the catalytic‐activity of their derived metal oxide/hydroxides for the oxygen evolution reaction (OER). Among all tested bimetallic MOF‐derived catalysts, the NiCoMOF exhibits superior catalytic activity for the OER with the lowest overpotentials of 301 mV and Tafel slopes of 42 mV dec−1 on a rotating disk glassy carbon electrode (RD‐GCE) in 1 mol L−1 KOH electrolyte at a current density of 10 mA cm−2. In addition, NiCoMOF was insitu grown in just 25 min by the MW synthesis on the surface of nickel foam (NF) with, for example, a mass loading of 16.6 mgMOF/gNF, where overpotentials of 313 and 328 mV at current densities of 50 and 300 mA cm−2, respectively, were delivered and superior long‐term stability for practical OER application. The low Tafel slope of 27 mV dec−1, as well as a low reaction resistance from electrochemical impedance spectroscopy (EIS) measurement (Rfar=2 Ω), confirm the excellent OER performance of this NiCoMOF/NF composite. During the electrocatalytic processes or even before upon KOH pre‐treatment, the MOFs are transformed to the mixed‐metal hydroxide phase α‐/β‐M(OH)2 which presents the active species in the reactions (turnover frequency TOF=0.252 s−1 at an overpotential of 320 mV). Compared to the TOF from β‐M(OH)2 (0.002 s−1), our study demonstrates that a bimetallic MOF improves the electrocatalytic performance of the derived catalyst by giving an intimate and uniform mixture of the involved metals at the nanoscale. [ABSTRACT FROM AUTHOR]

Research into hybrid nanofluid flow over a disk surface is growing due to numerous processes in marine or gas turbines, rotating disk reactors for biofuels generation, cooling of spinning equipment components and other industrial applications. The purpose of this research study is to examine the entropy generation for the transient thermocapillary flow of hybrid nanoliquid thin films across a disk surface with different shapes of nanoparticles. To analyze the nanomaterial, the Tiwari–Das hybrid nanofluid flow model is established, and in doing so, Prandtl's boundary layer theory is incorporated into this model. The energy equation considers the impacts of thermal radiation, two different kinds of heat sources — namely an exponentially space-dependent heat source and a linear thermal heat source — and viscous dissipation. The nonlinear partial differential equations, which explain the flow processes, are transformed into the nondimensional ordinary differential equations (ODEs). Once the ODEs have been constructed, they are next solved using the bvp4c technique. In addition, the surface drag force and the rate of heat transfer are both evaluated as functions of the shape factor of the nanoparticles that are disseminated in the base fluid. The influence of significant parameters on the flow fields is depicted graphically, and adequate physical explanations are provided for each representation. One of the important findings of this study indicates that the largest amount of heat transfer can be accomplished at the disk surface by employing nanoparticles with blade shape, while this physical quantity is the least when nanoparticles with spherical shapes are used. The temperature profile grows as the thermal and exponential heat sources increase. Entropy generation improves with the increase in either the magnetic parameter or the Brinkman number. [ABSTRACT FROM AUTHOR]

In this paper, we examine the shape effects of different nanoparticles of an incompressible, unsteady flow of a nanofluid Al 2 O 3 with water H 2 O as the base fluid over a rotating disk. Magnetic field results are also added. In this research, four distinct shapes of Al 2 O 3 nanoparticles, i.e., sphere, blade, cylinder and brick, have been employed. Every shape is suspended at the same volume. After using the Von Karman transformation, the Navier–Stokes equation, along with the magnetic field effect and the thermal energy equation, is numerically solved by using the bvp4c MATLAB solver. The effects of various parameters on the velocity field and temperature profile are illustrated graphically. This analysis is validated by comparing it to the previously described research. Furthermore, increasing the volume fraction parameter 0 ≤ ϕ ≤ 0. 1 % causes the radial, tangential, and axial velocities near the disk for the shapes brick, cylinder, and blade to decrease and increase for the shape sphere. The fluid rotating in front of the disk rotates more slowly for small values of the unsteadiness parameter α ̂. The magnetic field M has a significant influence on the axial flow when the suction parameter values are small, but this impact is limited when the suction parameter values are large. [ABSTRACT FROM AUTHOR]

The utilization of a ternary hybrid nanofluid, a recent development in the realm of nanofluids, can result in improved heat transfer. In the ongoing study, a ternary hybrid nanofluid flow is utilized, and it is carried out atop a porous spinning disc, which is exposed to a magnetic field, heat generation, thermal radiation, and Casson fluid. In this study, Blood/Water are taken as base fluids and (Ag–Au–Al2O3) are considered as a ternary hybrid nanoparticle. Nanoparticles made of gold and silver are put to use in a vast number of industries and fields, including nanotechnology and medicine. As a result of surface effects and quantum effects, these precious metals exhibit unique features in nanoform that play a vital role in with optical, magnetic, chemical, and mechanical behavior. Al2O3 unique optical, physical and biochemical qualities make it worthwhile for numerous uses, including nanophotonic, catalysis and the fabrication of high-energy composites. A set of relevant similarity transformations is used to generate non-dimensional forms of controlling paired nonlinear Partial Differential Equations (PDEs). MATLAB is used to perform a numerical solution with ODE45. In addition, the velocity outline decreases, and the temperature profile increases slightly before decreasing over a revolving disk when the values of magnetic parameters are increased. The distribution and radiant heat components heat up as the level gets higher. Aim and objectives of the study: The aim of this study is to analyze the Comprehensive Scrutinization of Ternary hybrid and Casson flow in a conducting porous rotating disk with internal heating. The primary objective of this analysis is to increase awareness of the impending energy crisis among those working in the industrial and technological sectors. Ternary nanoparticles (NPs) have a wide range of applications, which lends credence to the developed model. For example, Al2O3 can be used in a variety of ways that benefit society, it is used in water purification to remove water from the gas streams and extend people's lives. [ABSTRACT FROM AUTHOR]

In this article, we scrutinized the impact of nonlinear thermal radiation and an externally applied magnetic field over a rotating upward or downward disk on an unsteady 3D hybrid nanofluid flow in the presence of SWCNT(single-walled carbon nanotube)+ F e 3 O 4 (ferrosol ferric oxide) and MWCNT(multi-walled carbon nanotube)+ F e 3 O 4 with water as a base fluid. The foremost partial differential equations (PDEs) with boundary conditions of the flow model are converted into ordinary differential equations (ODEs) by considering suitable transformations and then solved numerically by using RKF-45 by implementing a shooting technique. Fluid flow characteristics are explored for various parameters and presented using graphs and charts. The results show that an increase in the radiation parameter causes an upsurge in the thermal field in the fluid flow of MWCNT+ F e 3 O 4 -water/SWCNT+ F e 3 O 4 -water hybrid nanofluid. The thermal profile and axial velocity profile of MWCNT+ F e 3 O 4 and SWCNT+ F e 3 O 4 with water-based hybrid nanofluid increase as magnetic parameter values rise but radial and azimuthal velocity profiles decrease. Also, the Nusselt number for MWCNT + F e 3 O 4 -water hybrid nanofluid is 0.35% less than SWCNT + F e 3 O 4 -water hybrid nanofluid. [ABSTRACT FROM AUTHOR]

This research explored the impact of air gap on torque and eddy current behavior of a magnet-north-pole rotating axial disk-type magnetic coupler using the magnetic equivalent circuit method. A magnetic equivalent circuit (MEC) model was developed to analyze the torque and induced eddy current behavior for the magnetic N-pole rotation angle 0° to 30° axial disk type magnetic coupler (MC). Torque equations were derived by combining Kirchhoff's law and the integral method, whereas induced eddy current equations were derived using Ampere's law. Flux leakage reluctance equations were obtained using an integral method. Furthermore, the study conducted 2D finite element simulations, and the results were validated against experimental data to ensure the accuracy and reliability of the proposed MEC model. Finally, the research findings suggested that an air gap length of 4 mm was an optimum length to obtain maximum torque and minimum magnetic saturation effects for a proposed MEC model of N-pole rotating axial disk type MC. [ABSTRACT FROM AUTHOR]

The ecology of marine life and other biotic processes, such as septicity, are influenced by the drive of microorganism cells in the fluid. Considering the transference mechanism in nanofluids including a microbial suspension is imperative for several chemical and medical applications. This study examines the bioconvection of an Al2O3-Graphene-CNT/water ternary hybrid nanofluid between two infinitely parallel spinning disks in a porous media under the influence of heat source/sink and radiation. The Cattaneo–Christov model has been employed to inspect the transference mechanism of mass and heat. The MATLAB function “bvp4c” is used to numerically tackle the governing equations. The relationship between the most relevant variables and the motile microorganism’s density, velocity, temperature, concentration of nanoparticles and other characteristics is graphically represented. Last, figures are provided to illustrate how several important elements relate to the Nusselt and Sherwood number, and local motile microbe density number. The heat transfer rate is seen to be higher at the upper disk than at the lower disk. A rise in the volume fraction of nanoparticles causes the heat transfer rate at both disks to increase. The outcomes of this study will be useful for a wide range of architectural designs, transportation systems, oil recovery systems with microbes, medical sectors and other industries that utilize nanofluids. [ABSTRACT FROM AUTHOR]

In order to reduce friction between moving elements in automobiles' heat exchange systems, SAE50 is a vital lubricant. Additionally, by preventing corrosion and abrasion of moving parts, it increases durability, reduces fuel consumption, and improves efficiency. SAE50 has a low thermal conductivity, despite this. The current inquiry is concentrated on how Zinc Oxide-Society of Automotive Engineers 50 nanolubricant flow (ZnO-SAE50 nanolubricant) through a permeable rotating disk is affected by a uniform horizontal magnetic field (UHMF) and thermal radiation. By employing the appropriate transformations, the governing modeled equations are changed into ordinary differential equations (ODEs). Then the ODEs are solved numerically by combining the Runge–Kutta-fourth-and-fifth Fehlberg's (RKF-45) order and shooting tactic. The findings show that radiation is crucial in enhancing heat transfer for the flow of ZnO-SAE50 nanolubricant over the disk surface. With higher heat source/sink parameter values, it is discovered that the temperature boundary layer produces energy, causing thermal profiles to rise. Further in this scenario, it is found that the increase in magnetic field decreases the fluid flow gradually at rate of 5–10%. [ABSTRACT FROM AUTHOR]

Modern micro- and nanotechnologies have achieved tremendous advancements in the development of nano-electronic devices in modern eras. These technologies are increasingly using advanced fluid media to improve performance. One of the emerging trends is the concurrent utilization of nanofluids and biological micro-organisms. In this study, we are inspired by bio-nanofluid rotating disk microorganisms used in medical engineering. This analysis examines the behavior of the Sutterby nanoliquid when subjected to convective heating conditions on a rotating stretched disk, taking into account the presence of mixed convective flow. Nanofluids, which consist of transparent liquids containing evenly dispersed tiny particles, show potential for improving heat transmission in a wide range of applications. The investigation, utilizing the Sutterby model, which represents a non-Newtonian fluid, covers a range of phenomena including mixed convective flow, convective heating, chemical reaction, and bioconvection. The controlling nonlinear differential system is addressed using suitable similarity transformations. The computer program MATLAB uses the Keller box approach to solve transformed ordinary differential equations (ODEs). Analyzed data have been acquired for important physical characteristics. The effects of these parameters are elucidated and analyzed quantitatively and visually across various profiles. Increasing the magnetic and material parameters leads to a decrease in axial, radial, and tangential speeds. Variations in the Biot number, thermophoresis, and thermal radiation directly affect the temperature increase in the fluid. The study’s findings could be used in oceanography, melting, moving organic fluids, and the process of cooling. [ABSTRACT FROM AUTHOR]

The aim of this study is to describe the influence of magnetic nanofluid, with steady, incompressible flow, and heat transfer rate with thermal radiation and porous medium between two parallel stretchable rotating disks. The basic fluid (engine oil) which contains different nanoparticles (TiO2 and Ag) and its thermophysical properties are investigated. In order to convert the nonlinearly partial differential main equations into dimensionless ordinary ones, a method of appropriate similarity transformations has been used and then solved by using the bvp4c shooting scheme in MATLAB software to get the numerical solutions. The results of novel effective non-dimensional parameters obtained on appealing physical industrial interest are established by utilizing the tabular and graphic outlines. The numerical results reported here were matched to the current limiting results in the literature and found to be in good agreement. Additionally, the temperature field of the hybrid nanofluid was significantly improved when compared to the conventional nanofluid. [ABSTRACT FROM AUTHOR]

A theoretical study is examined to investigate the effects of enthalpy and radioactive heat transfer in generalized Newtonian fluid flow due to an inclined rotating disk. In order to examine the shear thickening phenomenon, Carreau fluid model is utilized. Here for the first time, Carreau fluid model under the enthalpy, thermophoretic effect, binary mixture and solar radiation effects are examined near an inclined rotating disk. In this study, the fluid flow does not give an analytical solution of the Navier–Stokes equations, except for the limit case, that is for high Reynolds number. The flow inside three-dimensional boundary layer flow is determined by the von Kármán transformations. The boundary layer equations are converted into system of ordinary differential equations by using von Kármán inequalities and solved numerically by employing shooting method. The effects of shear thinning and shear thickening fluids show a increase behaviour for base flow profiles. Thermal conductivity and mass diffusivity increases the temperature and concentration distributions. The azimuthal velocities increases by increasing values of $ \lambda _{T} $ λ T and $ \lambda _{C}\ $ λ C parameters. We present the numerical solutions for different physical parameters and discussed them for radial and azimuthal velocities and for heat and mass transfer profiles through graphs and tables. [ABSTRACT FROM AUTHOR]

The thin film hybrid nanofluid (HNF) flow over a rotating stretching disk is considered for heat transfer (HT) enhancement applications. The water-based HNF consists of Ag and TiO2 nanoparticles (NPs). The film thickness is kept variable and the flow medium is also considered porous and variable. The variable porous space for the variable thickness of the thin film is the main focus of the present analysis. The variable thickness of the thin film improves heat transfer (HT) between the rotating disk and the surrounding fluid. Thicker film layers provide increased thermal resistance, reducing the (HT) rate, while thinner film layers enhance (HT) by minimizing the thermal resistance. Controlling the thickness of the film through the variable porous space allows for the optimization of (HT) in various engineering applications. Additionally, the presence of Ag and TiO2 nanoparticles (NPs) in the water-based HNF further enhances the heat transfer properties, making it an attractive option for heat transfer (HT) enhancement applications. Moreover, the stability of the variable thin film is more adjustable in the variable porous space. The artificial neural network is used to solve the problem and validate the obtained results, through Training, Testing, and error estimations. [ABSTRACT FROM AUTHOR]

Enhanced momentum and heat transport in a three-dimensional rotating disk boundary layer due to the consideration of a wavy disk surface is an already known fact in the literature. Such a transport enhancement is primarily associated with two fundamental attributes of the wavy disk: the increased surface area and the enhanced convection due to the surface undulations. However, there exists no further information about their individual role, mutual interaction, and individual share in enhancing the convective transport in the rotating disk boundary layer. This study aims to investigate these facts in detail by considering radially heterogeneous different wavy configurations on the disk surface. It is revealed that the said attributes contribute non-trivially to enhance the transport phenomena. Their impactful role is identified due to the strengths of circumferential and crossflow velocity components, the magnitude of flow swirl angle, and hence due to the coefficients of skin friction and their inter relationship. In this regard, a fundamental benchmark regarding the relative strength of the two coefficients of skin friction is identified from the flat disk case. Decisive observations regarding the impact of surface undulations and the increased surface area of the wavy disk on the enhanced convective transport are made with the aid of this benchmark. It is observed that the enhanced transport phenomena, especially the heat transfer, mainly depend upon the further dominance of the circumferential velocity component. In the situations of increased dominance of rotational flow K w > K f , the increased convection and surface area collectively contribute to enhance the thermal transport while in a reverse situation K w < K f the convection contributes adversely by even reducing the impact of the increased surface area. In the neutral situation where the dominance of rotational velocity is neither increased nor decreased (i.e., K w ≈ K f ), any increase in the transport phenomena is wholly due to the increased surface area. Therefore, the presence of surface undulations or increase in surface area is not the only criterion for an optimum rise in the transport phenomena, rather the impact of surface undulations on the velocity profiles is important which is manipulated due to their positioning on the disk surface. It is observed that the presence of surface undulations in the central and intermediate regions on the disk surface causes to increase the gradients of the crossflow velocity while their presence in the near rim location causes to enhance the gradients of the circumferential velocity. Thus, the configurations that have higher undulations in the near rim region outperform the other configurations. [ABSTRACT FROM AUTHOR]

The flow of a thin film over a rotating disk is crucial in many industrial applications, such as spin coating and jet cooling. Accurate prediction of hydrodynamic features is essential for optimizing these processes. In this study, we examine the vertical downward impingement of a circular Newtonian liquid jet on a horizontally rotating disk, focusing on two distinct regimes based on the rotation level. For a stationary disk and low rotation speed, a continuous hydraulic jump is formed, while increased rotation speed leads to the transformation of the jump into a hump. A composite mean-field thin-film approach is utilized to analyze the flow dynamics in different regions of the domain. The effects of gravity and rotation are considered by developing a model to capture the continuous jump and vortex structure. The influence of rotation on the laminar boundary layer near impingement is found to be negligible. Specific conditions for gravity and rotation are established to differentiate between the jump and hump regimes. The model is validated for both regimes against existing experiment. In the jump regime, the flow transitions from predominantly azimuthal near the disk to predominantly radial toward the free surface, while in the hump regime, the flow maintains an azimuthal character around the hump. The vortex associated with the jump diminishes with increasing rotation speed, indicating the occurrence of a type-0 jump on a rotating disk. For small gravity, the vortex does not form in conjunction with the jump at any rotation level. In the case of small rotation, large gravity, and large disk size, the film exhibits a hydraulic jump near impingement followed by a sharp rise in thickness near the edge of the disk. [ABSTRACT FROM AUTHOR]

This paper aims to find an exact solution for the von Kármán swirling viscous fluid flow caused by the infinite radius rotating disk with uniform suction. The swirling flow occurred at infinity or far from the rotating disk, and two conditions were considered. The first condition is when the direction of swirling flow at infinity is the same as the direction of angular velocity that the rotating disk has. The second condition is when the direction of the rotating disk and that of the swirling flow are opposites. When there are no swirling flow at infinity and no suction on the surface of the rotating disk, the pressure distribution is just a function of distance above the disk. The similarity transformation converts the governing equations from partial differential equations into ordinary differential equations and then is solved analytically with the HAN method. In this study, three cases were considered. The first case is a swirling flow at infinity that has the opposite and same direction of the rotating disk when there is no suction on the disk's surface. The second case is no swirling flow at infinity, but the suction occurs on the rotating disk's surface. The third one is both suction on the rotating disk and swirling flow. In the first case, it was observed that when the angular velocity of the fluid at a distance away from the disk is insignificant compared to the angular velocity of the disk, the skin friction coefficient reaches the maximum value and vice versa when the angular velocity of the fluid increases at a distance away from the disk, the value of skin friction coefficient decreases. In the second case, it was observed that the more the surface suction increases, the more the skin friction coefficient increases. Hence, the skin friction coefficient on a porous disk on which suction occurs is higher than on a normal non-porous disk. The results demonstrate that when parameters such as s = a = 0, the pressure will be a distance function above the disk if we put r = 0 . [ABSTRACT FROM AUTHOR]

The paper presents a closed system of three-dimensional hydrodynamic equations of averaged motion, intended for modeling spiral turbulence in a rotating astrophysical disk. Diffusion equations for the averaged vortex and an equation for the transport of the integral vortex helicity are derived. A general concept of the emergence of energy-intensive mesoscale coherent vortex structures in a thermodynamically open turbulent chaos subsystem, associated with the realization of a reverse cascade of kinetic energy in mirror-asymmetrical disk turbulence, is formulated. It is shown that negative viscosity in a rotating three-dimensional disk system is apparently a manifestation of cascade processes in helical turbulence, when reverse energy transfer from small vortices to larger ones takes place. It is also shown that the relatively long decay of turbulence in the disk is associated with the lack of mirror symmetry of the anisotropic field of turbulent velocities about its equatorial plane. The work comprises a review aimed at improving new models of astrophysical nonmagnetic disks, for which the effects of helical turbulence play a decisive role. [ABSTRACT FROM AUTHOR]

Micro- and nano-scale cellulosic fillers exhibit excellent dispersion and distribution within a thermoplastic matrix during the process of melt compounding or injection molding. In this study, spray-dried cellulose nanofiber (SDCNF) powders were manufactured using a pilot-scale rotating disk atomizer spray dryer. Bleached Kraft pulp (BKP), unbleached Kraft pulp (UKP), and old corrugated cardboard pulp (OCC) fibrillated at a fines level of 90% were used as feedstock materials for spray-drying. BKP-, UKP-, and OCC- SDCNFs were compounded with polypropylene using a twin screw co-rotating extruder. Maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the composite formulations. The tensile, flexural, and impact properties of SDCNF-filled PP composites increased at 10 wt% SDCNF loading. The presence of SDCNFs in the PP matrix resulted in faster crystallization and a 12% reduction in the degree of crystallinity of the neat PP. The coefficient of thermal expansion (CTE) of neat PP was reduced by up to 31% attributable to the presence of the SDCNFs. Application of the SDCNF-reinforced PP composites in 3D printing reduced the shrinkage rate of the printed neat PP by 39%, and the printability of the PP was significantly improved with the addition of the SDCNFs. [ABSTRACT FROM AUTHOR]

The authors have investigated the axisymmetric and three-dimensional, steady, incompressible, and bioconvective flow of Ag-TiO2/water hybrid nanofluid between two infinite and parallel rotating disks. Practical uses of flows between two rotating disks include brake systems in vehicles, engines, disks in computers, atomizers, rotating air cleaners, gas turbines, and evaporators. This study was conducted within a Darcy-Forchheimer porous medium and considered the impact of a magnetic field, heat source, and thermal radiation. The governing mathematical equations are transformed into coupled and nonlinear ordinary differential equations through similarity transformations. Subsequently, these equations are numerically solved using MATLAB's built-in function "bvp4c". A multilayer perceptron based artificial neural network (ANN) model has been formulated to predict the Nusselt number (heat transfer rate) on both the lower and upper surfaces of the disk. The model utilizes the Levenberg-Marquardt training algorithm, renowned for its exceptional learning capability, as the training method for the ANN. Moreover, the authors generated a dataset consisting of 84 data points for each case using numerical methods to construct the proposed Multilayer Perceptron Artificial Neural Network. The computed mean squared error values for the developed ANN model, targeting Nusselt number predictions, were found to be 2x10-6, 5x10-6, 9x10-6, and 3x10-6. Additionally, the regression (R²) values, serving as an additional performance parameter, were determined as 0.999317, 0.997672, 0.999963, and 0.999840, respectively. A comprehensive assessment of these outcomes, strongly affirms that the ANN model has been crafted with a high degree of accuracy for predicting Nusselt numbers. [ABSTRACT FROM AUTHOR]

AbstractNanofluids are assumed to be an excellent source of enhanced heat transfer with advanced thermophysical characteristics. Nanofluids are the backbone of the heating and cooling in the industrial processes. This research delves into the dynamics of a partially ionized Oldroyd-B nanofluid flowing between stretchable rotating disks. The study investigates heat transfer mechanisms incorporating a modified Fourier law and convective heat conditions. The viscoelastic fluid model presented here allows for the examination of relaxation and retardation times. Furthermore, the heat and mass transport of the Oldroyd-B nanofluid is characterized using a Buongiorno model, which considers thermophoresis and Brownian diffusion effects. Additionally, the study explores the impact of gyrotactic microorganisms in nanofluids, potentially enhancing environmental management strategies. The governing equations transform into dimensionless forms using Von Karman similarity variables. Numerical investigation of the anticipated model is conducted using the bvp4c scheme in MATLAB. The variation of different parameters in the dimensionless equations is illustrated through graphs and in tabulated format. The results indicate that increasing thermophoresis and Lewis numbers lead to a decrease in fluid concentration. Moreover, the temperature of the fluid rises at the lower disk and declines at the upper disk relative to the Biot number. The proposed model is validated through comparison with closely related published work. [ABSTRACT FROM AUTHOR]

Hybrid nanofluid models have the potential to significantly enhance heat transport in many applications, like coolant of electric devices, thermal energy storage, and heat exchangers. Therefore, the existing problem deals with the simulation of heat and mass transport due to the three-dimensional hybrid nanoliquid flow amid two gyrating disks containing silver Ag and titanium oxide TiO2 nanoparticles. Further, a magnetic field is employed normally to flow’s direction. Applications of Darcy–Forchheimer law are discussed in terms of the porous medium. The utilization of the Cattaneo–Christov model is considered for analyzing heat and mass transmission. Additionally, the influence of thermal radiation, non-uniform heat sink/source, and Brownian diffusivity are discussed in the flow analysis. The problem is designed on the basis of the higher-order nonlinear PDEs which are then converted to ODEs using appropriate variables. Using the numerical technique known as the shooting technique in MATLAB, the reduced mathematical structure is solved numerically. From this study, it is analyzed that the axial velocity profile is weakened near the upper disk but the axial velocity profile is amplified near the lower for upsurge in the magnetic factor and porosity parameter. Hybrid nanofluid concentration is lower for higher Schmidt numbers. [ABSTRACT FROM AUTHOR]

AbstractThis paper analyzes the flow of the Reiner-Rivlin hybrid nanofluid, considering the magnetic field and varying thermal conductivity between two spinning disks. Appropriate similarity variables are used to transform all dimensional equations into dimensionless form. A semi-analytical homotopy analysis approach applied to solve dimensionless equations and velocity profiles, temperature distribution, Nusselt number, skin friction, entropy generation, and Bejan number are presented graphically. Some key outcomes include that axial and tangential velocities decreases when porosity parameters increase. Additionally, higher Eckert number when varying from 1 to 1.3, increases the temperature near the center of the two disks from 1.02 to 1.18. The heat transfer rate goes up from 10.2767 to 10.3043 when thermal conductivity rises from 0.1 to 0.7. The entropy generation grows in proportion to the Brinkman number, Reynolds number, and the porosity parameter values. This research might enhance cooling, lubrication, and thermal management in automotive, aerospace, and biomedical industries. [ABSTRACT FROM AUTHOR]

The existing reservoirs of neutral atomic hydrogen gas (H I) in galaxies are insufficient to have maintained the observed levels of star formation without some kind of replenishment. This refuelling of the H I reservoirs is likely to occur at column densities an order of magnitude lower than previous observational limits (NH I, limit ∼ 1019 cm−2 at a 30″ resolution over a linewidth of 20 km s−1). In this paper, we present recent deep H I observations of NGC 5068, a nearby isolated star-forming galaxy observed by MeerKAT as part of the MHONGOOSE survey. With these new data, we were able to detect low column density H I around NGC 5068 with a 3σ detection limit of NH I = 6.4 × 1017 cm−2 at a 90″ resolution over a 20 km s−1 linewidth. The high sensitivity and resolution of the MeerKAT data reveal a complex morphology of the H I in this galaxy – a regularly rotating inner disk coincident with the main star-forming disk of the galaxy, a warped outer disk of low column density gas (NH I < 9 × 1019 cm−2), in addition to clumps of gas on the north-western side of the galaxy. We employed a simple two disk model that described the inner and outer disks, which enabled us to identify anomalous gas that deviates from the rotation of the main galaxy. The morphology and the kinematics of the anomalous gas suggest a possible extra-galactic origin. We explore a number of possible origin scenarios that may explain the anomalous gas, and conclude that fresh accretion is the most likely scenario. [ABSTRACT FROM AUTHOR]

The applicability of a fluidically heated spinning disk apparatus (SDA) was tested for investigating the influence of the tangential velocity on the deposition of particulate material systems, in particular on latex particles. First, the SDA was characterized for particle fouling investigations with micro glass beads as a model system, then, a first series of tests was carried out with a real material system, a vinyl acetate/Versa 10 copolymer. Experiments were performed for a duration of 1 h and a tangential velocity up to 0.3 m s−1. The fouling process was characterized by the local fouling layer thickness and the calculated local mass‐based fouling resistance. A decrease in fouling resistance along the radius of the rotating disk as a function of the tangential velocity was observed. [ABSTRACT FROM AUTHOR]

A nanofluid refers to a suspension of nanoparticles in a conventional fluid, which finds unique applications in diverse sectors, including engineering, technology, and medicine. When multiple nanoparticles are suspended, it creates a hybrid nanofluid. In this study, we aim to investigate an unsteady flow of hybrid nanofluid over a permeable shrinking inclined rotating disk subjected to heat radiation, magnetohydrodynamics and slip effects. The chosen nanoparticles for this study are alumina (Al2O3) and copper (Cu), incorporated into a base fluid of water (H2O) to create the hybrid nanofluid. An appropriate method of similarity transformation is executed along a set of partial differential equations that were reduced to a system of nonlinear ordinary differential equations, where numerical outcomes were then obtained via bvp4c in MATLAB software, with the influence of various parameters such as unsteadiness parameter, nanoparticle volume fraction, shrinking, radiation, magnetic and velocity slip parameters, shown in tables and figures. Multiple solutions (including dual, upper, and lower branch solutions) are identified for the governing similarity equations. Through the conducted stability analysis, it is determined that the upper branch solutions exhibit stability and physically realizable in practice, while the lower branch solutions are unstable. Our numerical findings showed that dual solutions exist when ε c ≤ ε ≤ - 1 , where ε c < 0 is the critical value of ε for which the boundary value problem poses physical solutions applicable in practice. Yet, the boundary value problem lacks a similarity solution for ε ≤ ε c ≤ 0 , and the complete set of partial differential equations needs to be solved numerically. Improvements in heat transfer rate are observed concerning the radiation parameter, nanoparticle fraction, and shrinking parameter. Furthermore, azimuthal velocity profiles show an increase influenced by velocity slip and magnetic parameters. The non-dimensional physical parameters, including stretching/shrinking, suction, slip, and unsteadiness, are also considered and their effects are presented in figures and tables. [ABSTRACT FROM AUTHOR]

This article presents a numerical analysis of the water-based hybrid nanofluid comprehending CuO and Fe3O4 nanoparticles between two rotating disks. The bottom and top disks each revolve around their respective axes of rotation. The two disks are positioned apart from one another. Along with Brownian motion and thermophoresis, it is intended that the flow will be electrically conducting, thermally radiative, and chemically reactive. The heat and mass transportation are also given attention in this study since they are crucial for industry, engineering, and everyday life which include hydraulic engines, electric motors, and generators. Using the bvp4c MATLAB function, the numerical solution of the modeled problem is ascertained. The results of the current numerical solution are compared with results from published research, confirming the accuracy of our model. The results of the present analysis are presented through figures and tables. Outcomes of this analysis show that stretching factor of the lower disk upsurges the axial velocity while the radial velocity exhibits dual behavior due to the stretching factor of the lower disk. Also, the stretching factor of the upper disk reduces the axial velocity while the radial velocity exhibits dual behavior due to the stretching factor of the upper disk. The tangential velocity distribution augments with the increasing rotation parameter. In comparison to nanofluid, hybrid nanofluid has stronger effects of the embedded factors on its Nusselt and Sherwood numbers at the lower disk, whereas at the upper disk, nanofluid has more effects of the embedded factors on its Nusselt and Sherwood numbers. This research might have an impact on various gadgets, including those that use air conditioning, chemicals and electronics. It is anticipated that the findings of this study will complement previously published work as well as provide information on engineering and industrial applications. [ABSTRACT FROM AUTHOR]

Controlling the distribution of the abrasive grains on the surface of the grinding tools in an appropriate way is important for improving the quality of grinding processing and meeting the workpiece precision requirements. In the present study, a novel method for the orderly arrangement of abrasive particles is proposed by using the liquid film flow on the surface of the rotating disk as the driving and controlling means for the uniform dispersion and position arrangement of abrasive particles. Computational fluid dynamics (CFD) simulations have been performed to clearly illustrate the trajectories of abrasive particles under the strong influence of liquid film flow on the rotating disk and reveal the effects of fluid flow, disk rotational motion, and the mixture viscosity on the particle distribution. A new abrasive grain arrangement device is designed and fabricated using this novel method. The operating parameters such as liquid volume flow rate, disk rotational speed, and liquid viscosity are adjusted to control the placement of abrasive grains on the surface of the grinding tool. An image processing tool is used to examine and analyze the arrangement results. The experimental results indicated that the application of the liquid film flow on a rotating disk to the abrasive grain arrangement can improve the arrangement of abrasive grains and get rid of the dependence on the template. [ABSTRACT FROM AUTHOR]

Biodegradable metallic materials are gaining attention for medical applications in short-term implants (15–500 days) because of their good mechanical properties, biocompatibility, and generalized corrosion. Most medical applications involve implant wear processes, particularly for bone fractures. Parallelepipedic specimens (dimensions 50 mm × 10 mm × 3 mm) were obtained by cutting the hot-rolled material processed from cast ingots of ZnMgY. To test the tribological performance of these stationary specimens, they were placed at the upper point of the machine's tribological contact. The rotating lower disk of the AMSLER machine (AMSLER & Co., Schaffhouse, Switzerland) is manufactured from AISI 52100 bearing steel with a 62–65 HRC hardness and a diameter of 59 mm both radially and axially. Frictional torque is the parameter that is measured. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to analyze the worn areas. The material behavior in the normal and wear states upon immersion in simulated body fluid (SBF) was evaluated. [ABSTRACT FROM AUTHOR]

For efficient heating and cooling applications, minimum wall shear stress and maximum heat transfer rate are desired. The current study optimized the local skin friction coefficient and Nusselt number in Al2O3-Cu/water hybrid nanofluid flow over a permeable shrinking rotating disk. First, the governing equations and boundary conditions are solved numerically using the bvp4c solver in MATLAB. Von Kármán's transformations are used to reduce the partial differential equations into solvable non-linear ordinary differential equations. The augmentation of the mass transfer parameter is found to reduce the local skin friction coefficient and Nusselt number. Higher values of these physical quantities of interest are observed in the injection case than in the suction case. Meanwhile, the increase in the magnitude of the shrinking parameter improved and reduced the local skin friction coefficient and Nusselt number, respectively. Then, response surface methodology (RSM) is conducted to understand the interactive impacts of the controlling parameters in optimizing the physical quantities of interest. With a desirability of 66%, the local skin friction coefficient and Nusselt number are optimized at 1.528780016 and 0.888353037 when the shrinking parameter ( λ ) and mass transfer parameter ( S ) are −0.8 and −0.6, respectively. [ABSTRACT FROM AUTHOR]

Experimental and numerical investigations are conducted on a rotating disk from the perspective of convective heat transfer to understand the effect of heating on the stability of flow. A non-invasive approach with a thermal camera is employed to determine local Nusselt numbers for different rotational rates and perturbation parameters, i.e., the strength of the heat transfer. A novel transient temperature data extraction over the disk radius and an evaluation method are developed and applied for the first time for the air on a rotating disk. The evaluation method utilizes the lumped capacitance approach with a constant heat flux input. Nusselt number distributions from this experimental study show that there is a good agreement with the previous experimental correlations and linear stability analysis on the subject. A significant result of this approach is that by using the experimental setup and developed approach, it is possible to qualitatively show that instability in the flow starts earlier, i.e., an earlier departure from laminar behavior is observed at lower rotational Reynolds numbers with an increasing perturbation parameter, which is due to the strength of heating. Two experimental setups are modeled and simulated using a validated in-house Python code, featuring a three-dimensional thermal model of the disk. The thermal code was developed for the rotating disks and brake disks with a simplified geometry. Experimentally evaluated heat transfer coefficients are implemented and used as convective boundary conditions in the thermal code. Radial temperature distributions are compared with the experimental data, and there is good agreement between the experiment and the model. The model was used to evaluate the effect of radial conduction, which is neglected when using the lumped capacitance approach to determine heat transfer coefficients. It was observed that the radial conduction has a slight effect. The methodology and approach used in this experimental study, combined with the numerical model, can be used for further investigations on the subject. [ABSTRACT FROM AUTHOR]

The authors have investigated the axisymmetric and three-dimensional, steady, incompressible, and bioconvective flow of Ag-TiO2/water hybrid nanofluid between two infinite and parallel rotating disks. Practical uses of flows between two rotating disks include brake systems in vehicles, engines, disks in computers, atomizers, rotating air cleaners, gas turbines, and evaporators. This study was conducted within a Darcy-Forchheimer porous medium and considered the impact of a magnetic field, heat source, and thermal radiation. The governing mathematical equations are transformed into coupled and nonlinear ordinary differential equations through similarity transformations. Subsequently, these equations are numerically solved using MATLAB's built-in function "bvp4c". A multilayer perceptron based artificial neural network (ANN) model has been formulated to predict the Nusselt number (heat transfer rate) on both the lower and upper surfaces of the disk. The model utilizes the Levenberg-Marquardt training algorithm, renowned for its exceptional learning capability, as the training method for the ANN. Moreover, the authors generated a dataset consisting of 84 data points for each case using numerical methods to construct the proposed Multilayer Perceptron Artificial Neural Network. The computed mean squared error values for the developed ANN model, targeting Nusselt number predictions, were found to be 2×10−6, 5×10−6, 9×10−6, and 3×10−6. Additionally, the regression (R2) values, serving as an additional performance parameter, were determined as 0.999317, 0.997672, 0.999963, and 0.999840, respectively. A comprehensive assessment of these outcomes, strongly affirms that the ANN model has been crafted with a high degree of accuracy for predicting Nusselt numbers.

A series of interactive experiments are conducted to analyze the drag reduction technology with a rotating disk apparatus that combines microgroove structure and drag‐reducing additives including polyethylene oxide (PEO), cetyltrimethyl ammonium chloride (CTAC), and sodium salicylate (NaSal). By varying the disk type, concentration of drag‐reducing additives, temperature, and Reynolds number (Re), the corresponding drag reduction rates are obtained effectively. The experimental results indicate that adding CTAC strengthens the heat degradation and shear resistance of PEO; while PEO can enhance the ability of CTAC to form micellar structures and balance energy distribution at low concentrations. Moreover, the synergistic effect of these two additives presents a better drag reduction performance with a maximum drag reduction rate of 24.1%; while the microgroove structure enhances the effect of active drag reduction. Therefore, the combination of active and passive drag reduction technology broadens the application of energy saving and consumption reduction in hydraulic rotating machinery. [ABSTRACT FROM AUTHOR]

Acoustic vortices (AVs) carry orbital angular momentum (OAM), showing great promise in advancing communication, biomedicine, and metrology. An ideal OAM generation method that realizes the tunability of AV topological charge and working frequency in a compact way is strongly desired. Here, we utilize aerodynamic dipole sources from a rotating disk to generate AV. This method generates AVs with different topological charges through the interference of these dipole sources at the angular rotation frequency and its multiples. These AVs exhibit high purity, and their three-dimensional characteristics are explored. Furthermore, our experiment demonstrates that the generated AVs significantly enhance the sound field amplitude at their working frequency, which is the product of the topological charge and angular frequency. The results also verify that this amplitude enhancement effect is positively correlated with the AV's stability and achieves the contactless detection of disk rotation information. The demonstrated method provides expanded versatility for OAM-based applications. The tunability of acoustic vortices topological charge and working frequency is pivotal for efficient optical angular momentum generation, but its manipulation typically involves bulky setups. Here, the authors use aerodynamic dipole sources from a rotating disk to generate acoustic vortices with different topological charges in a compact setup. [ABSTRACT FROM AUTHOR]

Because of their tunable porosity and specific surface area, porous materials are of high interest for the purification of wastewater by adsorption as well as in electrocatalysis, where, in particular, developing metal‐free carbon‐based catalysts for the oxygen reduction reaction (ORR) is researched. The carbon spheres presented here can meet these two requirements simultaneously. Porous polyacrylonitrile (PAN) spheres were firstly prepared by droplet shaping cum nonsolvent induced phase separation. Then, they were converted to nitrogen‐doped carbon spheres by two‐step carbonization via preoxidation and pyrolysis. During the pyrolysis step, carbon dioxide was used to reopen the pores of the materials that had been blocked after the preoxidation step. By this way, specific surface area values of carbon spheres of more than 1000 m2/g could be obtained. Best performing carbon materials (C#3) showed high adsorption capacity (e.g., 296 mg/g for methyl orange at solute equilibrium concentration of 24 mg/L in water). The XPS analysis revealed that only quaternary (N‐Q) and pyridinic (N‐6) nitrogen sites were found in these carbon spheres. The best ORR performance was found also for C#3 carbon spheres, with a potential of 0.81 V versus reversible hydrogen electrode (RHE) at −1 mA/cm2 and electron transfer number of 3.5 at 0.6–0.8 V versus RHE, as determined by rotating disk or rotating ring disk electrode tests. In conclusion, all results confirm that these PAN‐derived carbon spheres are potentially valuable materials for both wastewater treatment by adsorption and electrocatalytic oxygen reduction. [ABSTRACT FROM AUTHOR]

The flow of ferronanofluid due to a rotating disk finds its significant place in biomedical sciences, pharmaceuticals, electronics, aerodynamics etc. Entropy generation appears in the systems/processes where its minimization is needed because it prohibits the decay of available energy which in turn boosts the efficiency of the associated thermal systems where it matters the most. In view of these added advantages, the flow and heat transfer behavior of ferronanofluid subject to slip, suction, electromagnetic field, Darcy–Forchheimer effect, and viscous dissipation, Ohmic heating and thermal radiation has been explored within this research. In addition, the role of entropy minimization associated with the flow concern has been analyzed. The apposite governing equations are numerically treated via shooting method. The important outcome of the study include infusion of more porous matrix develops controlled rotating flow due to both deformed disks. Rise in slip parameter augments flow velocity for stretched RD while that shows the adverse effect for shrunk RD. Controlled rate of heat transportation due to enhanced convective heating is significant for shrunk RD than that of stretched RD. Further, low Prandtl fluids, low molecular heat conduction and liquid friction yield entropy minimization thereby leading to uplift efficiency of thermal systems. [ABSTRACT FROM AUTHOR]

A method for microextraction recovery and concentration of tilmicosin phosphate in washings from surfaces of pharmaceutical equipment for its determination by high-performance liquid chromatography with spectrophotometric detection was proposed. The developed method involved dispersion of the extractant (1-dodecanol) in an aqueous solution of a sample while rotating a cotton disk equipped with an inserted magnetic stirrer followed by crystallization of the extract upon cooling the extraction system. The extractant was applied beforehand to the cotton disk. Effective dispersion of the extractant in the aqueous phase during rotation of the cotton disk ensured a high degree of analyte recovery (94%). The detection limit of tilmicosin phosphate (3σ) reached 0.7 mg/L. The determined concentrations ranged from 2 to 250 mg/L. The analytical capabilities of the developed method were demonstrated using quantitative determination of tilmicosin phosphate in washings from surfaces of pharmaceutical equipment after completion of its cleaning as examples. [ABSTRACT FROM AUTHOR]

For its applications in nuclear reactors, food processing, chemical engineering, water emulsions and thermal power generating systems, the significance of irregular heat source and Arrhenius energy on electro-magnetohydrodynamic hybrid nanofluid flow over a rotating stretchable disk with nonlinear radiation have been investigated. The flow problem has been modeled utilizing the modified Buongiorno model and the thermophysical characteristics of water-based Cu − F e 3 O 4 hybrid nanoliquid. Effects like passive control of nanoparticles, hydrodynamic slip and convective boundary conditions are also heeded to boost the realistic nature of this work. Further, engineering quantities like moment coefficient and pumping efficiency of the disk are also elucidated which boosts the novelty of this research work. The modeled governing equations are transmuted into a system of first-order ODEs, with the help of apposite similarity transformations, which are then numerically resolved using the finite-difference based bvp5c algorithm. It is noticed that per unit increase in the electric parameter decreases the skin friction coefficient by 41.75% and increases the heat transfer rate by 15.31%. It is also observed that the entrainment velocity is directly proportional to the changes in electric field parameter and is inversely proportional to the changes in volume fraction of copper and magnetite nanoparticles. [ABSTRACT FROM AUTHOR]

Rotating-disk generated flows find potential applications in industry such as cooling of electronics, car-breaking system, wind turbine engineering and others. Current article formulates heat transfer in the steady revolving flow of viscoplastic fluid obeying Bingham model over a rotating disk. Simulations are conducted by applying partial slip wall conditions, which are Robbin-type and non-linear in velocity components. Contribution of viscous dissipation, representing the conversion of mechanical energy into thermal energy caused by internal friction, is added in the analysis. Furthermore, the phenomenon of Joule heating due to the consideration of magnetic field affected flow is accounted for. The self-similar problem that arises after implementing Von-Kármán variables is computationally addressed using the MATLAB tool bvp4c. Significance of yield stress on the Von-Kármán flow under slip boundary assumption is elucidated through graphical results. Additionally, the implications of frictional heating and Joule heating on the development of a thermal boundary layer in a Bingham fluid are clarified. As the yield stress τ y increases, the velocity profiles meet their respective far field conditions at smaller vertical distances, and therefore a higher torque is required by the disk. Noticeably, considering the slip effect not only lowers the torque that the disk requires, but it also boosts disk's rate of cooling—a desirable outcome in practical applications. The reliability of the mathematical model is assessed by performing uncertainty analysis of the computational data. [ABSTRACT FROM AUTHOR]

A mathematical model is developed for a non-Newtonian tangent hyperbolic fluid over a rotating disk by extending the concept of standard von Karman swirling flow. The impact of magnetic field, melting heat transfer, viscous dissipation, and Joule heating are incorporated. The existing leading nonlinear partial differential equations are modified into ordinary differential equations by using similarity transformation. Then, the bvp4c solver is adopted to investigate the solution of modified nonlinear ordinary differential equations with boundary constraints. The probable error (PE) is computed to examine the reliability of the correlation coefficient ( r ∗ ) of the physical parameters. The presence and absence of power-law index parameter are depicted and compared by graphical and tabular form. The rotation parameter is positively correlated and the Weissenberg number is negatively correlated in the presence of the power-law index. Moreover, the Eckert number shows a dual nature in temperature and entropy generation profiles. Finally, velocities, i.e., radial and azimuthal are diminished by enhancing magnetic parameter. [ABSTRACT FROM AUTHOR]

The reaction order plays a crucial role in evaluating the response rate of acid-rock. However, the conventional two-scale model typically assumes that the reaction order is constant as one, which can lead to significant deviations from reality. To address this issue, this study proposes a novel multi-order dynamic model for acid-rock reaction by combining rotating disk experimental data with theoretical derivation. Through numerical simulations, this model allows for the investigation of the impact of acidification conditions on different orders of reaction, thereby providing valuable insights for on-site construction. The analysis reveals that higher response orders require higher optimal acid liquid flow rates, and lower optimal Hþ diffusion coefficients, and demonstrate no significant correlation with acid concentration. Consequently, it is recommended to increase the displacement and use high-viscosity acid for reservoirs with high calcite content, while reducing the displacement and using low-viscosity acid for reservoirs with high dolomite content. [ABSTRACT FROM AUTHOR]

In the course of the search for a flow pattern optimal for culture growth in vortex bioreactors, our experiments discovered striking flow patterns that existing theoretical models cannot explain. Three immiscible liquids fill a vertical open cylindrical container whose sidewall is still, while the bottom disk rotates driving a fluid motion. The centrifugal force pushes the lower liquid (L, aqueous glycerol) from the axis to the periphery near the bottom, creating its toroid circulation that in turn drives middle liquid (M, sunflower oil) and upper liquid (U, alcoholic glycerin) circulations. With increasing rotation, counterflows develop near both interfaces LM and MU in upper fluids: the liquids move toward (away from) the axis below (above) the interface that seems paradoxical. Then, unusual topological transformations occur again in the middle liquid flow caused by competition between effects of radial friction and centrifugal forces. Near cylinder boundary at interface MU, new reverse circulation zone developed where the radial velocity became zero and then change sign. These counterintuitive results wait for their theoretical explanation and formulation of new contact conditions at the LM and MU interfaces. [ABSTRACT FROM AUTHOR]

In order to solve the problem of severe vibration of the pump due to the larger pulsations of the output flow caused by the continuous change of the relative phase between the plunger and the rotating disk, a triangular damping groove-type rotating distributor disk vibration damping structure was designed. The vibration damping structure overflow area model was established, and the simulation model of the alternating flow distribution pump containing the rotating distributor disk vibration damping structure was built by using AMESim. Based on the simulation model, the influence of structural parameters such as depth angle, width angle and circumferential angle of the triangular groove on the flow pulsation was analyzed, and the optimal scheme of the rotating distributor disk vibration damping structure of the alternating flow distribution pump was formed. The results show that the addition of a triangular damping groove in the transition region of the rotating distributor disk can significantly reduce the flow pulsation, and the pulsation rate of the alternating flow distribution pump is 31.4% with the triangular groove circumferential angle of 21°, the width angle of 100°, and the depth angle of 16°. The study provides a reference for the design and parameter selection of the vibration damping structure of the rotating distributor disk of the alternating flow distribution pump. [ABSTRACT FROM AUTHOR]

This study theoretically investigates the temperature and velocity spatial distributions in the flow of a copper–water nanofluid induced by a rotating rigid disk in a porous medium. Unlike previous work on similar systems, we assume that the disk surface is well polished (coated); therefore, there are velocity and temperature slips between the nanofluid and the disk surface. The importance of considering slip conditions in modeling nanofluids comes from practical applications where rotating parts of machines may be coated. Additionally, this study examines the influence of heat generation on the temperature distribution within the flow. By transforming the original Navier–Stokes partial differential equations (PDEs) into a system of ordinary differential equations (ODEs), numerical solutions are obtained. The boundary conditions for velocity and temperature slips are formulated using the effective viscosity and thermal conductivity of the copper–water nanofluid. The dependence of the velocity and temperature fields in the nanofluid flow on key parameters is investigated. The major findings of the study are that the nanoparticle volume fraction significantly impacts the temperature distribution, particularly in the presence of a heat source. Furthermore, polishing the disk surface enhances velocity slips, reducing stresses at the disk surface, while a pronounced velocity slip leads to distinct changes in the radial, azimuthal, and axial velocity components. The study highlights the influence of slip conditions on fluid velocity as compared to previously considered non-slip conditions. This suggests that accounting for slip conditions for coated rotating disks would yield more accurate predictions in assessing heat transfer, which would be potentially important for the practical design of various devices using nanofluids. [ABSTRACT FROM AUTHOR]

Context. Dust particles in protoplanetary disks rotate at velocities exceeding those of the surrounding gas due to a lack of pressure support. Consequently, they experience a headwind from the gas that drives them toward the central star. Radial drift occurs on timescales much shorter than those inferred from disk observations or those required for dust to aggregate and form planets. Additionally, turbulence is often assumed to amplify the radial drift of dust in planet-forming disks when modeled through an effective viscous transport. However, the local interactions between turbulent eddies and particles are known to be significantly more intricate than in a viscous fluid. Aims. Our objective is to elucidate and characterize the dynamic effects of Keplerian turbulence on the mean radial and azimuthal velocities of dust particles. Methods. We employed 2D shearing-box incompressible simulations of the gas, which is maintained in a developed turbulent state while rotating at a sub-Keplerian speed. Dust is modeled as Lagrangian particles set at a Keplerian velocity, therefore experiencing a radial force toward the star through drag. Results. Turbulent eddies are found to reduce the radial drift, while simultaneously enhancing the azimuthal velocities of small particles. This dynamic behavior arises from the modification of dust trajectories due to turbulent eddies. [ABSTRACT FROM AUTHOR]

Context. An optically thick, geometrically thin accretion disk (AD) around a supermassive black hole might contribute to broad-line emission in type 1 active galactic nuclei (AGN). However, the emission line profiles are most often not immediately consistent with the profiles expected from a rotating disk. The extent to which an AD in AGN contributes to the broad Balmer lines and high-ionization UV lines in radio-loud (RL) AGN needs to be investigated. Aims. This work aims to determine whether the AD can account for the double-peaked profiles observed in the Balmer lines (Hβ, Hα), near-UV (MgIIλ2800), and high-ionization UV lines (C IVλ1549, CIII]λ1909) of the extremely jetted quasar 3C 47. Methods. The low ionization lines (LILs) (Hβ, Hα, and Mg IIλ2800) were analyzed using a relativistic Keplerian AD model. Fits were carried out following Bayesian and multicomponent nonlinear approaches. The profiles of prototypical high ionization lines (HILs) were also modeled by the contribution of the AD, along with fairly symmetric additional components. Results. The LIL profiles of 3C 47 agree very well with a relativistic Keplerian AD model. The disk emission is constrained between ≈102 and ≈103 gravitational radii, with a viewing angle of ≈ 30 degrees. Conclusions. The study provides convincing direct observational evidence for the presence of an AD and explains that the HIL profiles are due to disk and failed-wind contributions. The agreement between the observed profiles of the LILs and the model is remarkable. The main alternative, a double broad-line region associated with a binary black hole, is found to be less favored than the disk model for the quasar 3C 47. [ABSTRACT FROM AUTHOR]