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With a constant push to shrink size and elevate power density, the heat flux in GaN-based devices is drastically intensified, requiring effective cooling to control junction temperature. This work presents an embedded manifold microchannel cooling (EMMC) arrangement targeted at mitigating junction temperature, in which microchannels are directly etched in the GaN substrate to extract heat generated due to self-heating. The single-phase laminar flow of deionized water through near-junction microchannels has been investigated in a unit-cell mimicking a recently reported GaN power converter with EMMC arrangement. The effects of geometrical parameters of the manifold and microchannel, heat flux and flow rate on the thermal-hydraulic performance of the unit-cell model are thoroughly studied. High heat transfer coefficients in the order of 10(5) W/(m(2).K) associated with the near-junction microfluidic single-phase flow are acquired, which demonstrates the excellent heat extraction capability of EMMC applied to GaN-based devices. The unit-cell model in the prediction of the thermal performance of a large-scale EMMC multifinger GaN device is in good agreement with experiment and capable of providing detailed fluid flow and temperature distributions for design optimization. Furthermore, a capped diamond heat spreader is integrated with the EMMC GaN device to reduce junction thermal spreading resistance. It is shown that high die heat flux in the range 0.86-3.01 kW/cm(2) can be effectively removed for the 10-mu m-thick diamond capped GaN-on-SiC EMMC device within a junction temperature range 48-110 degrees C. This new EMMC arrangement complemented with capped diamond holds promise as an ultimate near-junction cooling solution that facilitates the implementation and development of high-power compact GaN-based devices.

We consider the effect that an upstream cylinder has on the effective inertial collection efficiency of a downstream cylinder. We consider an initially uniform distribution of particles moving past a cylindrical fiber in a potential crossflow and numerically calculate the resulting particle distribution far downstream of the fiber using finite differences. We then investigate the effect that the downstream distribution of particles has on the effective inertial collision efficiency of a downstream test cylinder oriented parallel to the first. We show that the effective collision efficiency of the test cylinder depends on its relative offset in the transverse direction (normal to the flow) with respect to the upstream cylinder. For relatively small offsets there is complete shielding, and no particles collide with the test cylinder. As the offset increases, a growing effective collision efficiency is observed leading to a significant enhancement relative to the collision efficiency of an isolated cylinder for intermediate offsets and Stokes numbers close to unity. Importantly, we observe relative gains in effective collision efficiency above 100% for a range of Stokes number and offset values. For larger offsets and Stokes numbers, the effect of the upstream cylinder on the effective collision efficiency of the test cylinder decreases and eventually becomes negligible. Detailed results are provided for Stokes drag acting on the particles and we also show that a non-linear drag has negligible effect on the observed trends for the conditions relevant to filtration systems. These results suggest that the arrangement of fibers has a substantial effect on inertial particle impaction even when neighboring fibers do not alter the flow field around each individual collector. Moreover, periodic arrangements with specific orientations with respect of the flow could lead to a significant enhancement of the inertial collision of particles on an array of collectors, thus contributing towards a better filtration performance.

In this study, artificial neural network (ANN) was used to predict forced convection heat transfer enhancement from microscale pin fin heat sinks under various operating conditions and at different geometries. Experimental data acquired from the literature were employed to train the ANN model. Different numbers of training cycles, layers, and neurons in the network were investigated to design an effective neural network. The performance of the trained network was tested using the mean squared error and the most accurate one was selected to predict the average Nusselt number. Mean absolute percentage errors between the ANN output and the experimental datapoints were calculated and compared with the existing correlations. This machine learning method offers significant improvement for thermal performance prediction and could be a reliable tool for determining convective heat transfer in microscale pin fin heat sinks.

(1) Background: Metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacingarthroplasty (HRA) was presumed to provide superior functional outcomes compared to metal-onpolyethylene (MoP) THA. (2) Methods: We compared muscle mass, power, step test asymmetry, andpatient-reported outcomes between MoM THA/HRA and MoP THA. A total of 51 MoM THA/HRAsand 23 MoP THAs participated in the cross-sectional study at a mean of 6.5 (2.4–12.5) years postoperatively. Muscle mass was measured by Dual energy X-ray Absorption (DXA) scans and musclepower in a Leg Extensor Power Rig. Step test asymmetry was obtained with an Inertial MeasurementUnit (IMU). The patients completed the Harris Hip Score (HHS) and the Copenhagen Hip and GroinOutcome Score (HAGOS). (3) Results: The MoM THA/HRA group had a greater inter-limb differencein hip muscle mass compared to the MoP THA group (p = 0.02). Other inter-limb differences inmuscle mass and power were similar (p > 0.05). Muscle mass of the thigh and calf area and musclepower in both legs were higher in MoM THA/HRA compared to MoP THA (p < 0.009). Step test timeasymmetry when ascending was lower in MoM THA/HRA compared to MoP THA (p = 0.03). HHSand HAGOS scores were similar between groups (p > 0.05). (4) Conclusion: Overall, we could notverify the hypothesis that MoM THA/HRA contributes to superior functional outcomes compared toMoP THA.

The characteristics of hybrid nanofluid flow contained copper (Cu) and cobalt ferrite (CoFe2O4) nanoparticles (NPs) across a squeezing plate have been computationally evaluated in the present report. In biomedical fields, in very rare cases fluid flow through a static channel. Similarly in industrial sights, we are also often observed that the fluid flows through comprising plates rather than fixed plates (flow in vehicle’s engine between nozzles and piston). CoFe2O4 and Cu nanoparticles are receiving huge attention in medical and technical research due to their broad range of applications. For this purpose, the phenomena have been expressed in the form of the system of PDEs with the additional effect of suction/injection, heat source, chemical reaction, and magnetic field. The system of PDEs is simplified to the dimensionless set of ODEs through similarity replacements. Which further deals with the computational approach parametric continuation method. For the validity and accuracy of the outcomes, the results are confirmed with the existing works. The results are displayed and evaluated through Figures. It is detected that the hybrid nanoliquid has a greater ability for the velocity and energy conveyance rate as related to the nanofluid. Furthermore, the energy profile declines with the consequences of unsteady squeezing term, while enhances with the effects of suction factor, heat absorption and generation, and lower plate stretching sheet.

The main goal of this work is to explore exact analytical solutions for the transient hybrid nanofluid flow with heat transfer owing to a moving/exponentially accelerating infinite flat vertical plate with heat flux boundary conditions. Further, the uniqueness of this work is to investigate the impact of different types of hybrid nanofluids on heat transfer and unsteady flow features in the existence of thermal radiation and heat flux boundary conditions. For engineering variables like Nusselt number and skin friction coefficient, along with temperature and velocity profiles, graphs are used to reveal the results of the Laplace transform method. Increased heat transfer and friction values have been found for an exponentially accelerating plate. The findings can be utilized in heat exchangers as well as in electronics and chemical and biological reactors.

In this research paper, the study focuses on results of heat radiation on Casson fluid flowing in three dimensions toward a linearly stretched sheet packed with porous media when a magnetic field is present, as well as when Prandtl number effects when there is a porous medium involved. The Roseland approximation, which integrates a heat radiation’s impact into the energy equation, is used to incorporate thermal radiation into this research endeavour. To be used in this fluid flow the basic governing partial equations for this fluid flow were changed from linear ordinary differential equations by converting non-linear partial equations with similarity variables are utilised. The numerical solutions to the resultant linear ordinary duality equations are obtained by the use of the finite element approach. Graphical representations of the effectiveness and accuracy of this finite element approach are provided for a variety of characteristics as the permeability (K), Casson fluid (β), and magnetic field (M) parameters Stretching sheet parameter (C), Prandtl number (Pr) and Thermal radiation component (R). and conditions. A comparison of our numerical findings with previously published data (S. Nadeem, R. U. Haq, N. S. Akbar, and Z. H. Khan, Alexandria Eng. J. 52, 577 (2013)) reveals a a high level of consistency among the two sets of data.

This is often a detailed think about on the effect of the foremost well-known shape of organizing nowadays, social media, on understudies over all ages. Also, the paper moreover looks at to discover the different impacts social media has on understudies and what endeavors can be made to move forward social media experience for the different understudy clients of social media. With the assistance of writing survey and quantitative investigation of essential information, the issues and challenges confronted by understudies whereas utilizing social media. The discoveries make a difference as it helps us to conclude on the off chance that the social media emphatically or contrarily influences the life of an understudy

The article widely reviewed the variation of the heat transfer characteristics and fluid flow of various nanofluids based on physical and chemical parameters like velocity, geometry, viscosity, friction factor, and pressure drop. It also shed light on the stability of these nanofluids in various conditions. The article mainly focuses on the effects on Reynolds number and Nusselt number, thermal changes in the environment and the cooling solution used for nanofluids, and the dependency of concentration of nanoparticles in the working fluid. Apart from this, it also discusses the geometry in which the fluid is kept and the motion or forces it experiences and simulations to observe and analyse the flow of fluid and heat through these nanofluids. Also, this article presents the improvement in the pool boiling heat transfer rates through nanofluids with twisted tapes and corrugated patterns such as corrugated double-tube exchangers. This article concluded with the results obtained from experimental analysis and numerical methods. According to the study, as nanofluids get bigger, their velocity increases. When particle size is increased from 10 nm to 100 nm, the alumina-water nanofluid’s velocity rises by 22.22%. For Al2O3/water nanofluid with a particle size of 10 nm, the rate of expansion in wall shear stress when concentration is raised from 0% to 5% is 75%. The geometry of the tubes affects the properties of heat transport. When a triangular tube having a twisted tape is utilized in the system, the Nusselt number is enhanced by 34.7% and 52.5% in turbulent and laminar flow respectively.

This paper presents a numerical analysis study of the dynamic and thermal performance of a convective flow of water-copper nanofluids in a double-pass flat solar collector. The flow inside the confined space between the glazing and the insulation is governed by the continuity, momentum, and energy equations. The problem addressed is solved via a CFD ANSYS code using the finite volume method to discretize the equations of the mathematical model. The dynamic and thermal fields are obtained for different values of the volume fraction (φ = 0%, φ = 3%, and φ = 8%). These results are compared with other results mentioned in the literature. The results obtained allowed us to define the influence of these different parameters on the convective nanofluid flow in the solar collector. The increase in the volume fraction further promotes heat transfer. The presence of nanoparticles expects a critical part of the convective heat exchange.

The present article addresses the steady and laminar magnetohydrodynamics (MHD) flow of a micropolar nanofluid between two porous disks. The fluid is flowing uniformly in the inward and upward directions from both disks. The microrotation of the nanoparticles acts an important role in the flow regime. To show its significance, a comparative study of the analytical results and numerical results is presented. Titanium dioxide is chosen as nanoparticles in the water-based fluid. An appropriate transformation is used for transforming PDEs into ODEs. These nonlinear ODEs are computed by the differential transform method (DTM). The consequences of the Reynolds number, material parameter, and magnetic parameter on the radial velocity, axial velocity, and microrotation profile are graphically presented and discussed. The results calculated by DTM and the results calculated numerically are compared and tabulated. This comparison shows the accuracy and validity of DTM. The coefficient of skin friction is also tabulated and compared with the numerical result. At the end of this study, it is concluded that the behavior of the radial and the axial velocities and the microrotation profile are almost the same in the case of the Reynolds number and the magnetic field parameters.

The main goal of the present study is to invetigate Bödewadt flow and thermal analysis of radiative ternary hybrid nanofluid over rotating disk subject to second order slip. The ternary hybrid nanofluid contains nanoparticle-1 as Al2O3(spherical), nanoparticle-2 as CNT (cylindrical), nanoparticle-3 as graphene (platelet) and base fluid as water. Casson model is adopted to show the non-Newtonian behavior of the flow of Al2O3+CNT+Graphene+Water ternary hybrid nanofluid. The transformed non-dimensional equations are solved numerically by using bvp4c package on MATLAB. The major outcomes of the work include amplified non-Newtonian parameter upgrades the radial, azimuthal and axial velocities of mono nanofluid, binary hybrid nanofluid and ternary hybrid nanofluids. Thermal boundary layer is thickest for non-Newtonian ternary hybrid nanofluid compared to mono nanofluid and binary hybrid nanofluid.

The study explores to analyze the problem of peristaltic mechanism of tangent hyperbolic fluid through porous medium in an asymmetric channel. The two-dimensional peristaltic flow of hyperbolic tangent fluid in an asymmetric channel through porous medium is analyzed under the long wavelength and low Reynolds number assumptions. The flow is investigated in a wave frame of reference moving with velocity of the wave. The perturbation series is used to obtain the solution for stream function, pressure gradient and pressure rise. The results were studied for different values of the physical parameters of the problem and illustrated graphically. It is observed that pressure rise diminishes for the larger values of Darcy number. Pressure gradient decreases for increment in Darcy number. Hyperbolic tangent fluid model anticipates the shear thinning phenomenon very accurately and are being used mostly in laboratory experiments and industries.

Nanofluids became an essential solution for the improvement of efficient heat transfer fluids. Thus, it’s necessary to optimize their propreties. This paper investigates the effect of the temperature and the volume fraction on the thermo-physical properties of different nanofluids (Mono and hybrid) such as: Density, thermal conductivity, dynamic viscosity, kinematic viscosity, heat capacity and enthalpy in various nanoparticule concentrations and operating temperature. Two nanoparticles Al2O3, CuO were added to three different conventional base fluids namely: Therminol VP-1; Sylthrem 800; Dowtherm A, with several volume fractions, and various temperatures (200–400 °C). A numerical model was developed using MATLAB software, to evaluate the behavior of each thermo-physical property of the nanofluid that can be used as a working fluid in CSP applications and compared with their conventional fluids. The results show an improvement in thermo-physical properties compared to pure fluids for an optimal value of 4% for Al2O3. Also, the increase in temperature plays an important role in the decrease in viscosity, and their influence on other properties has also been noticed while the addition of nanoparticles to the pure fluid allow to increase the thermal conductivity by 13%. Finally, the (Al2O3 + CuO/Dowtherm A) hybrid nanofluid sems to be attractive to use in CSP applications.

This paper discusses transient two-dimensional boundary layer laminar viscous incompressible free convective flow of nanofluids containing carbon nanotubes (SWCNTs and MWCNTs) over a moving vertical cylinder in the presence of thermal radiation and temperature oscillation. The governing boundary layer equations are converted to a dimensionless form and then solved using the Crank Nicolson type’s unconditionally stable and convergent implicit finite difference method. With diverse parameters such as Grashof number (Gr), volume fraction (Φ), phase angle (ωt), and thermal radiation parameter (N), numerical results are achieved for velocity and temperature profiles along with Nusselt number and skin friction coefficients. The numerical results are analysed in detail using graphs for both water-based nanofluid and kerosene-based nanofluids with single and multi-wall carbon nanotubes as the nanomaterials. It has been found that CNTs Water-based nanofluid has higher temperatures, velocities, skin friction coefficient values for all Gr, N, Φ, and ωt when compared to kerosene-based nanofluid with CNTs. But, Kerosene-based CNTs nanofluid has a higher Nusselt number coefficient values concerning all Gr, N, Φ, and ωt than water-based CNTs nanofluid.

The stability analysis of tri-hybrid nanofluid is examined theoretically in the presence of three types of gravity modulation. Normal mode techniques have been carried out for linear stability analysis, and the truncated Fourier series method is used for non-linear analysis. We observe both stationary and oscillatory convection is possible in the bottom-heavy case, and the onset of convection gets delayed in stationary in comparison to oscillatory. We also observe the onset of convection is earlier in the case of top-heavy with respect to bottom-heavy. Heat and mass transport start earlier in the day–night profile in comparison to other profiles of gravity modulation. In the graph of nusselt number, mass transfer of the first particle increases with an increase in Rn1 value while other two concentration Rayleigh numbers (Rn2, Rn3) does not have any effect on first concentration nusselt number. If we generalize the problem for n-different types of nanoparticles, then two cases may be possible (1) Top-heavy-ordinary nanofluids will be the most stabilizing case. (2) Bottom-heavy-nanofluids with n-type particles will be the most stabilizing case. The most stabilizing case is possible with the same ratio of Rn in the top-heavy, whereas the opposite result is found in the bottom-heavy.

In this paper the effects of laser irradiation on MHD Non-Newtonian hybird nanofluid flow and bioheat transfer have been proposed. If the tissue is vertical and there is a sudden change in environmental temperature, free convection will flow and bioheat transfer must be solved in conjunction with hydrodynamics equations of nanofluid (blood) motion. The bioheat transfer within the tissue can be formulated in mathematical model as an initial and boundary value problem. The non-linear system of partial differential equations is solved analytically by applying Laplace transform with the help of finite Fourier sine transform. The energy equation assumes that the tissue temperature and blood phase are identical. The blood velocity profile is decreasing in parallel with the rise of fluid parameters. This implies that the medication conveyance therapy lessens the tumor volume and helps in annihilating malignancy cells by applying small parameters such as Casson parameter. The bioheat tissue temperature distribution increases as the both magnetite nanoparticles and multi-walled carbon nanotubes increase. Therefore, we enhance the physical properties of the blood by immersing the magnetite nanoparticles through it. The hybrid volume of nanoparticles will be more effective in enhancing blood velocity and tissue temperature by laser nanoparticle method.

Stability of Rivlin-Ericksen category of nanofluid saturated in a continuous medium bounded by infinite horizontal plates has been studied. Energy equation has been supplemented with the variables belonging to the Brownian motion and thermophoresis of nanoparticles. For the linear and the non-linear stability analyses, other than the specific boundary conditions appraised with the physical situation, the boundary conditions for the flux of nanoparticle mass, in analogy with the passive behaviour of temperature at the boundaries have been explored. The novelty of the paper is that the stationary convection exists for both positive as well as negative Rn (concentration Rayleigh number) and the convection sets in earlier in comparison to a porous medium. It is also shown that the non-existence of the oscillatory convection in a Newtonian nanofluid has been ruled out for Rivlin-Ericksen nanofluid, though it exists only for negative Rn, the situation when the density of the fluid is greater than the density of nanoparticle. The viscoelastic parameter of Rivlin-Ericksen nanofluid annihilates the instability of oscillatory convection. Under non-linear stability analysis, the truncated representation of Fourier series approach has been used and the parameters belonging to the heat and mass transfer have been evaluated. It is shown that corresponding to certain parameters, the rate of heat and mass transfer rises rapidly. The valuable results are shown graphically and verified numerically.

This paper is centered on the numerical and analytical solution of a non-Newtonian Casson nanofluid flow problem in the presence of vertical magnetic field. Brownian motion and thermophoretic forces are introduced due to the addition of nanoparticles and; the magnetic field adds an extra Lorentz’s force term along with Maxwell’s equations. Using Normal mode technique, the system of PDEs with the corresponding boundary conditions is reduced to a system of ODEs. The Galerkin-type weighted residual method is used to get a numerical solution for the formulated differential system. Numerical simulation is carried out to make the investigation helpful for practical applications like nano-drug delivery systems as in clinical and medical research, magnets are extremely important to create three-dimensional images of anatomical and diagnostic importance from nuclear magnetic resonance signals. Comparisons of the numerical results with previously published results are made and fine agreements are noted for the considered values of the parameters. The impact of magnetic field, Casson parameter and nanoparticle parameters are discussed for different types of boundary conditions (free–free, rigid-free and rigid–rigid). The system is found to be the most stable for more realistic rigid–rigid boundaries out of three different boundaries. For the purpose of numerical computations, blood has been considered as the Casson nanofluid. The novelty of the work lies in the fact that the strong stabilizing influence of Lorentz force on blood-based Casson nanofluid enables the red blood cells to pass through the blood in a more streamlined fashion which may play a significant role in human health, more specifically in the cardiovascular system. Further, although the Casson parameter hastens the onset of convection yet Casson fluids are more stable as compared to regular fluids.

Enhancement of cooling performance of heat transfer fluids can contribute to downsizing of thermal systems. Analysis of thermal behavior of four cooling water based nanofluids (CuO, Al2O3, ZnO and SiO2) in a circular duct is carried. Modeling of heat transfer and fluid flow is based on 3D non-linear differential elliptical equations and finite volume method approach. The Brownian motion is considered in modeling of the nanofluid behavior. A code is developed based on SIMPLER and TDMA algorithms. Hydrodynamic and thermal fields are examined for nanoparticles volume fractions range 0% ≤ Φ ≤ 4% and spherical nanoparticles mean diameter in the range 27 nm ≤ dnp ≤ 78 nm. Results show that the local and circumferentially average Nusselt number increases with increasing the nanoparticles volume fraction and decreases with the nanoparticles size. The maximum local Nu is observed at the bottom of the duct. SiO2–water nanofluid shows the best thermal performance as well as the strongest secondary flow. Increasing the nanoparticles volume fraction increases the secondary flow strength. Using 4 vol.% nanoparticles of 27 nm mean diameter improves Nu by 12%, 7%, 5%, and 3.7% for SiO2, Al2O3, ZnO, CuO, respectively, when compared to the cooling performance of water alone.

Numerical simulations of water-Al2O3 nanofluid flow in a rectangular channel with two trapezoidal obstacles have been studied, which has rmarkable effect in various engineering applications. The governing equations have been solved using SIMPLEC algorithm and FLUENT software has been used to visualize the simulation results. Motivation of this work is to examine the dynamic behavior of laminar water-Al2O3 nanofluid flow for volume fraction, ψ = 0%, 2%, and 4%. The present study analyzes different hydrothermal flow phenomena with the variation in obstacle height and ψ. Moreover, the simulation results, such as the profiles of velocity, normalized temperature (θ), poiseuille number (CfRe), local Nusselt number (Nu), average Nusselt number (Nuavg) and friction factor (f) have been portrayed with the variations in ψ and Reynolds number (Re). It has been observed that the obstacles increase the convective heat transfer (HT) significantly. At Re = 100, for all the configurations it has been found that the velocity profile become more pronounced for ψ = 4% as compared to ψ = 0%. A linear relationship has been found between the values of f and ψ. It is also found that an increase in Re increases vortex length. It is also shown that variation of volume fraction (ψ) and obstacle height resulted in an indicative change in the normalized temperature and velocity along the center line. In type-1 obstacle configuration, it has been found that Nuavg increases by 6.6% at ψ = 2%, and the same increases by 10.73% at ψ = 4% as compared to that at ψ = 0%. Moreover, it has been found that in type-2 obstacle configuration, value of f increases by approximately 7.9% at ψ = 2% and 13.84% at ψ = 4% as compared to that at ψ = 0%.

Combined effects of the magnetic field, heat source/sink, and homogeneous–heterogeneous chemical reaction on the three-dimensional fluid flow over a stretching sheet have been examined in this paper. For originality and practicality, the influence of non-linear convection on hybridised nanoparticles of titanium dioxide (TiO2) and silver (Ag) in the non-Newtonian engine oil (EO) are introduced into the governing equations, which are then dimension-free by utilizing appropriate transformations. Williamson fluid model has been employed to determine the rheological features of the considered fluid mixture. MATLAB inbuilt bvp4c solver and Keller box method are proposed for the numerical solution of current fluid theories. Physical elaboration of the graphs is given to recognize the influence on fluid flow and heat transport mechanism in different rising conditions. Based on results, the implication of magnetic field and Williamson parameters restrict the fluid flow for both nanofluid (TiO2/EO) and hybrid nanofluid (TiO2 + Ag/EO). Special case studies of the shape factor effect show more enhancement in heat transfer rate for cylindrically shaped nanoparticles 25.8162% followed by brick-shaped 20.3286% and spherical-shaped 17.0583%. This study will provide better insight into applications including aircraft refrigeration, lubrication, plastic processing, engine and generator cooling, and so forth.

The natural convection of TiO2-Water-Nanofluid in a cubic cavity, containing a hot block under the influence of the magnetic field was studied numerically. The verticals walls are cold, the bottom wall is hot and the other walls (top, front and rear) are adiabatic. This work aims to visualize the importance of taking into account the three-dimensionality of the flow in the presence of magnetic field as well as the impact of the addition of nanoparticles on heat exchange rate evolution. The governing equations are solved using the finite volume method and the SIMPLER algorithm is used for pressure-velocity coupling. The problem was simulated at different Rayleigh numbers (103 ≤ Ra ≤ 106), Hartmann numbers (0 ≤ Ha ≤ 90) and inclination angles of the magnetic field (0 ≤ ω ≤ 135°) as well as nanoparticles volume fraction (φ = 0%, φ = 5%) with fixed Prandtl number (Pr = 7). The thermal conductivity and dynamic viscosity of the nanofluid are estimated by taking into account temperature-dependent properties, using Corcione’s correlations. Based on the cooling optimization of cold walls along with comparative analysis between 3D cavity and 2D cavity, the obtained results show that the buoyancy force enhances the heat exchange, while the magnetic field produces opposite effects. When the buoyancy force is dominated, the intensification of heat transfer becomes large, compared to the case where conduction is dominant. The qualitative difference between a 3D and 2D configuration is remarkable for higher Ra, and becomes smaller when the magnetic field is applied horizontally or vertically with relatively high intensity. But, quantitatively, the 3D flow is far from being considered as a 2D flow for all pertinent parameters control. Finally, adding nanoparticles enhances heat transfer for both configurations, the best transfer rate is obtained for ω = 0.

The present research aims to enhance the convective heat transfer coefficient inside the tube of the double pipe heat exchangers, this is carried out by mixing the water with copper oxide (CuO) nanoparticles. In this study, the effects of nanofluid with different volume concentrations from 0 to 0.4%, flowrates of nanofluid inside the tube, and water flow through the annulus, and inlet temperature inside the tube were examined on the Nusselt number. From the analysis, experiential data found nanoparticles have a significant enhancement of the convective heat transfer coefficient inside the tube of the double pipe. The heat transfer coefficient inside the tube increases as the Reynolds numbers of the flow inside the tube, and water flow through the annulus increase. The convective heat transfer coefficients reached maximum values at 0.35% of the volume concentrations of CuO nanoparticles and then decreased as the increase of the volume concentrations increases. The fiction factor increases as the volume concentrations of nanoparticles increases. Empirical correlations are presented describing the Nusselt number and the friction factor of the nanofluid flow inside the tube of the double pipe and concealing the affecting parameters in such process.

Nanofluids are potential coolants for heat transfer applications because of their excellent thermal characteristics. Experimentally the thermophysical properties of ZrO2/ethylene glycol nanofluids are determined at 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% vol. concentrations. A two-step method is used to prepare the stable nanofluids. The ZrO2/EG nanofluids properties were estimated over temperature ranging from 20 °C to 60 °C. From the experimental data, a multi-layer perceptron feed-forward back propagation artificial neural network was developed. Additionally, new correlations were proposed for all the thermophysical properties. The experimental analysis showed that thermal conductivity is enhanced by 19.6% at 60 °C and viscosity is enhanced by 86.62% at 20 °C at 1.0% vol. of nanofluid, density is enhanced by 4.9%, and specific heat is decreased by 4.2% at 1.0% vol. of nanofluid and at 60 °C, over base fluid data. The proposed ANN model succeeded in predicting the target property with minimum RMSE. The results of the developed artificial neural network and its correlation analysis perfectly agree with the experimental data.

Conventional investigations on fluid flows are undertaken with an assumption of constant fluid properties. But in reality, the properties such as viscosity and thermal conductivity vary with temperature. In such cases, considering these variabilities aids in modelling the flows with accuracy. Particularly, studying the flow of graphene based nanofluids with variable properties makes the best of both the advantageous thermophysical properties of graphene nanoparticles in heat transfer and the variable fluid properties in accuartely modelling the flow. In this article, the flow of graphene oxide nanofluid along a linearly stretching cylinder under no-slip and convective boundary conditions is investigated, by taking the base fluid viscosity to be a temperature dependant function. Buongiorno model is adapted to develop the flow of graphene nanofluids including the influence of variable heat source, cross-diffusion effects and the effects of nanoparticle characteristics such as thermophoresis and Brownian motion. The modelled equations are transformed and are numerically solved using linearization method. The impacts of embedded parameters including the Dufour and Soret numbers on temperature, concentration and velocity profiles of the chosen nanofluid and their consequent impacts on the predominant cause for the generated entropy are studied. The obtained results are depicted and interpreted in detail. From the tabulated values of skin friction and the values of Sherwood and Nusselt numbers, it is inferred that the conductive heat and mass transfer can be enhanced by variable viscosity parameter and skin friction can be reduced by Soret number. Furthermore, entropy generation is analysed and Bejan number is calculated to be lesser than 0.5, thus demonstrating the dominance of irreversibilty to fluid friction and mass transfer.

International audience; In this paper we develop a decoupled finite particle method (DFPM) to simulate non-isothermal free surface flow. This method can not only promote the accuracy of kernel approximation, but also insure the computational efficiency comparing with some improved particle methods. To model the non-isothermal viscous fluid flow, the particle discretization of heat conduction is derived explicitly. The Rusanov flux is introduced to alleviate the random oscillation of pressure. A corrected dynamic boundary method with a soft repulsive model and combined with particle shifting technology is developed further to model the complex wall-boundary problem. The comprehensive particle model is validated firstly through solving the non-isothermal Couette flow and the high-speed injection molding of a holey cavity, which is compared with other numerical results or experiments. Then, we extend the present method to solve the 2D/3D droplet impacting onto micro multi-structured surface for the capacity of present boundary treatment. The convergence, computational efficiency and operating conditions on the behavior of flow regime are analyzed. All numerical results show that the comprehensive numerical model has a considerable potential to simulate non-isothermal free surface flow.

Separation and identification of different proteins is one of the most fundamental tasks in biochemistry that is typically achieved by electrophoresis and Western blot techniques. Yet, it is challenging to perform such an analysis with a small sample size. Using a principle analogous to these conventional approaches, we present a label-free, single-molecule technique to identify different proteins based on the difference in their size, charge, and antibody binding. We tether single protein molecules to a sensor surface with a flexible polymer and drive them into oscillation by applying an alternating electric field. By tracking the nanometer-scale oscillation of each protein molecule via high-resolution scattering microscopy, the size and charge of each protein molecule can be determined simultaneously. Changes induced by varying the buffer pH and antibody binding are also investigated, which allows us to further expand the separation ability and identify two different proteins in a mixture. We anticipate our technique will contribute to single protein analysis and biosensing.

Sensitivity and speed of detection are contradicting demands that profoundly impact the electrical sensing of molecular biomarkers. Although single-molecule sensitivity can now be achieved with single-nanotube field-effect transistors, these tiny sensors, with a diameter less than 1 nm, may take hours to days to capture the molecular target at trace concentrations. Here, we show that this sensitivity-speed challenge can be addressed using covalently functionalized double-wall CNTs that form many individualized, parallel pathways between two electrodes. Each carrier that travels across the electrodes is forced to take one of these pathways that are fully gated chemically by the target-probe binding events. This sensor design allows us to electrically detect Lyme disease oligonucleotide biomarkers directly at the physiological high-salt concentrations, simultaneously achieving both ultrahigh sensitivity (as low as 1 fM) and detection speed (15 s). This unexpectedly simple strategy may open opportunities for sensor designs to broadly achieve instant detection of trace biomarkers and real-time probing of biomolecular functions directly at their physiological states.

In this paper, a comprehensive numerical analysis of a bladeless Tesla microturbine is presented. Various studies on the effects of Tesla design parameters have shown promising results. However, the limitations associated with the inherent nozzle design have often highlighted the low efficiency of the turbine. Therefore, the study was carried out using computational fluid dynamics (CFD) to demonstrate the efficiency of the turbine as a function of the performance of different openings of the inlet nozzles, i.e., as 1-opening and individual pitot tube opening. In this work, a validation study was performed with the existing manuscript before further investigating the effects of the different openings of the inlet nozzles. The results show that the configuration of 4 inlets with 4 openings (4i4o) results in higher velocity and pressure distribution compared to 4 inlets with 1 opening (4i1o). Consequently, 4i4o obtained a higher torque value compared to 4i1o with a difference of 10%. Hence, the thrust and efficiency values for the 4i40 were 33.69% and 34.30%, respectively, higher compared to the 4i1o. The performance of the Tesla turbine with the specified optimal configuration increased very significantly compared to the previous research studies. It can be concluded that the introduction of the functional theory of the ‘pitot-tube’, which considers the gaps individually by having a separate inlet for each of them, had a great impact on the performance of Tesla turbine.

A two-fold sensitivity of the zero-pressure gradient (ZPG) turbulent boundary layer (TBL) wall-pressure spectrum to different RANS model parameters is investigated for a flat plate case, which is a close approximation to the aircraft fuselage or wing. The alteration in the mean square pressure fluctuations due choice of semi-empirical pressure model and the choice of computational model parameters like solver, near wall grid clustering, measuring location, and flow velocity are separately studied. The underlying effect of different TBL parameters in the said sensitivity has been studied while numerically replicating wind tunnel experiments and in-flight tests considering different RANS configurations. Initially, the best-predicting pressure spectrum models are selected by comparing them with available in-flight and wind tunnel test data. Subsequently, the accuracy of all the individual model parameters in predicting mean TBL flow quantities like wall shear stress, boundary layer thickness, displacement thickness, momentum thickness, etc., and eventually mean square pressure (MSP) is estimated. The sensitivity of the mean square pressure fluctuations value to the TBL flow quantities and the near-wall grid clustering is observed to be significant. In general, family of models is found to be best in terms of numerical convergence and closeness when compared to the experimental MSP values. family of models is suggested to be avoided while estimating MSP in flat plate TBL case

The current study simulated the three-dimensional Williamson nanofluid flow model over a stretching sheet in the presence of Cason parameter explored with hybrid carbon nanotubes. The governing equations are modelled and interpreted using adequate similarity transformations and physical phenomena to convert into nonlinear coupled ordinary differential equations. In order to solve these equations, a Python coding program is used with an open-source boundary value problem solver. The obtained numerical results are validated with related literature results. The results are interpreted through graphs and tables with thermos-physical parameters like thermal Peclet number. It is found that the growth rate of heat transfer from fluid to wall with booming non-linear thermal radiation, radiation, and thermal Peclet number parameters

Nanotubes have been designed to be significantly larger than any other material, and these cylindrical carbon molecules have exceptional properties that are important for nanoscience and nanotechnology. Due to their exceptional thermal conductivity and mechanical and electrical properties, carbon nanotubes are used as additives to improve heat transfer in various industrial applications. The study analyzed a steady, two-dimensional, carbon nanotubes (CNTs) flow on aligned magnetohydrodynamics mixed convection over a static or moving wedge with convective boundary conditions. The CNTs used are single-wall carbon nanotubes (SWCNTs), multi-wall carbon nanotubes (MWCNTs), and water as the base fluid. The similarity transformation was used to reduce the partial differential governing equations into ordinary differential equations. Then, the reduced equations were solved using fourth-fifth order Runge–Kutta–Fehlberg and coded into Maple Software. The results of velocity and temperature profiles were illustrated graphically while the results of skin friction coefficient and Nusselt number were presented in tabulated data. It is found that the velocity profiles increase, and temperature profiles decrease when the angle of aligned magnetic field parameter, the interaction of magnetic parameter, convective parameter, and total angle of the wedge parameter number increase. For case where Biot number and volume fraction of nanoparticles parameters increase, the velocity profiles decrease, and temperature profiles increase. SWCNTs have increased skin friction and Nusselt numbers due to their higher density and thermal conductivity compared to MWCNTs. The finding of this study will benefit the who works in research and development in a range of industries and the mathematics body of knowledge as it provides new information to people who are interested in this field.

A 3-dimensional incompressible laminar flow and heat-transfer in a plate-fin heat exchanger (PFHE) where investigated numerically in this article. The influence of mounting a longitudinal vortex generator (LVG) on the offset rectangular-triangular fin (ORT) in the PFHE, on thermal and hydro-dynamic fields are presented. The novelty of this study is by attaching a LVG to an offset strip fin (OSF) surface. The cases of study for the PFHE are established, by using a built-in rectangular winglet pair type RWP longitudinal vortex generator carried out and fitted on this fin to improve the convective heat transfer of the (ORT) fin while minimizing pressure loss. The upper and lower plates are exposed to constant heat flux and the working fluid is air where chosen under a laminar range of RE (600 to 1400). The laminar flow and heat-transfer are governed by continuity, momentum and energy equations. ANSYS FLUENT (2021 R1) is used to get the numerical results, based on the finite volume method. The performance of the VG is assessed for an optimum winglet attack angle (45°), as well as by modifying the geometrical size parameters, namely the height and placement (L) of the RWP LVG. The result shows that the Nusselt number reaches its optimum enhancement values by using a common flow up CFU built-in rectangular winglet pair type RWP VG with a height and entrance length of (h=1.25mm, L=0.5mm), by 22.23% as compared with base case configuration (ORT). Finally, a two more LVG are tested with the optimum conditions of the RWP, which they are a delta winglet pair (DWP) and trapezoidal winglet pair (TWP). In addition, the temperature fields for the primary and secondary flows were shown in contour and streamline diagrams

At the end of 2019, the COVID-19 virus began to appear and quickly spread throughout the world. It transmits the infection to the respiratory tract by the transmission of pathogens within bioaerosols during speaking, coughing, and sneezing. Therefore, understanding the dynamics of aerosols plays an important role in developing mitigation strategies against droplet infections. Computational modeling, using fluid and computational dynamics, has become a useful feature in studying and visualizing the diffusion of micro-droplets that are difficult to reach using experimental methods. Through this study, the effects of using cloth face masks and social distancing, both recommended by the World Health Organization to the general public to avoid rapid transmission of COVID-19, were determined. This study made a comparison between different structural masks and the difference between social distancing with different porous masks at the droplet diameter during breathing from 0.5 µm to 2.5 µm. The results showed the effectiveness of wearing masks in reducing the risk of infection transmission. Also, with lower mask porosity, lower air permeability means higher filtration efficiency, trapping airborne particles more effectively, especially for small infection-carrying particle sizes, and, therefore, lowering the required social distancing. From the comparison, it is concluded that sample 6 has the highest efficiency of 82.9% compared to other samples (1, 2, 3, 4, and 5), which have efficiencies of 77.1%, 77.1%, 74.3%, 80.0%, and 65.7%, respectively

This study aimed to investigate the effect of morphology on permeability and fluid wall shear stress of porous scaffold. Fluids passing through the scaffold were analyzed using the computational fluid dynamics (CFD) method, and tortuosity was analyzed using the finite-different analysis (FDA) method. Based on the results, the higher the porosity, the higher the permeability. In contrast, by increasing the tortuosity, the permeability decrease. Then, control curvature in the negative Schwarz p design has the potential to increase the permeability, consequently, decrease the specific surface area. Therefore, the design negative Schwarz p was proposed met the requirements for a good implant which the permeability value was in the range of trabecular bone.

This paper examined the significance of Cattaneo-Christov's theories on the flow of chemically reacting fluid past a stretching surface with thermophysical parameters. The mathematical modelling of the physical problem was represented by partial differential equations. The set of partial differential equations was simplified by employing suitable similarity variables to obtain the system of coupled nonlinear ordinary differential equations. The transformed equations were later solved using the spectral relaxation method. The spectral relaxation method employs the basic concept of the Gauss-Seidel relaxation techniques. The outcome of this method was presented in graphs and tables. The thermal radiation parameter was found to enhance the velocity and temperature distributions. Also, the effect of the magnetic field parameter was found to decline the velocity profile. It was found that the Brownian motion parameter greatly influences the velocity as well as temperature profiles