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The current research aims to study how changing the endwall shape of the inner cylinder affects the appearance of Ekman cells and the onset of Taylor vortices. A two-dimensional numerical method simulates the flow between two concentric cylinders, with the inner cylinder rotating while the outer cylinder and the upper and lower endwalls remain at rest. The method of solving the Navier-Stokes equations for incompressible viscous flows is provided by the Ansys Fluent software, which is based on the finite volumes method. The geometric parameters, such as the radius ratio (η) and the height ratio (Г), are fixed at η = 0.9 and Г = 9.85, respectively. The working fluid is an aqueous solution (μ = 48 mPa.s, ρ = 1050 kg/m³). The study focuses on modeling four configurations (A, B, C, and D): configuration (A) includes two flat plate endwalls, configuration (B) features a hemispherical upper endwall and a flat lower plate endwall, configuration (C) consists of a flat upper endwall and a hemispherical lower endwall, and configuration (D) comprises two hemispherical endwalls. The obtained results indicate that the appearance of Ekman cells and the transition to Taylor vortex flow are specifically delayed for configuration (D). Additionally, the friction coefficient is affected by the modification of the endwalls. Indeed, configuration (D) contributes to a reduction of the skin friction coefficient by approximately 43% at the appearance of Ekman cells, and by 20% near the appearance of Taylor vortices compared to configuration (A). [ABSTRACT FROM AUTHOR]

This study investigates the impact of magnetohydrodynamic (MHD) inclination on unsteady gaseous micro-flow past a sinusoidally moving horizontal plate in the slip flow regime. The exact solution of the momentum equation with the corresponding boundary conditions and the expression for skin friction are obtained and solved analytically. The effects of varying magnetic field inclinations, phase angle, Hartman number, driving force frequency, and Knudsen number have been considered. Numerical and graphical simulations show that MHD inclination significantly influences flow behavior, leading to velocity reductions and fluid friction enhancements. The findings of this research have important implications for designing and optimizing micro-scale devices, such as micro-pumps, micro-heat exchangers, and micro-valves, in engineering applications. [ABSTRACT FROM AUTHOR]

This research communication explores the Darcy - Forchheimer flow of a chemically reacting non-Newtonian Maxwell fluid over a stretching sheet, incorporating the Cattaneo – Christov heat flux under a convective boundary condition. The fluid flow is described by a set of partial differential equations, which are subsequently transformed into a system of nonlinear ordinary differential equations. To solve these equations numerically, the BVP4C Method was employed after appropriately defining non dimensional variables and implementing similarity transformations. The impacts of diverse active parameters such as Deborah parameter, Darcy-Forchheimer parameter, magnetic parameter, Biot number, and porous parameter are examined on the velocity, temperature, and concentration profiles. In addition, the value of the Skin friction, Nusselt number is calculated and presented through tabular forms. [ABSTRACT FROM AUTHOR]

The current investigation aims at to examine the effect of radiation absorption, heat generation and Dufour number on MHD Casson fluid flow past an exponentially accelerated vertical plate in a porous medium with chemical reaction. The governing equations for momentum, energy and concentration are solved by implementing the Laplace transformation method. Skin friction, rate of heat transfer and rate of mass transfer expressions are also extracted and depicted in tabular form. Investigation simulates that Casson parameter diminished the fluid velocity, whereas energy flux due to a mass concentration gradient improves the temperature field of the flow problem. In addition to this, temperature field is observed to be developed under the influence of radiation absorption and heat generation. Furthermore, the effects of different non-dimensional parameters on velocity field, temperature fluid and species concentration are exhibited graphically. [ABSTRACT FROM AUTHOR]

The study investigates the unsteady free convective two-dimensional MHD flow past a vertical porous plate with convective surface boundary condition in porous medium in slip flow regime under the action of variable suction velocity. Analytical solutions are obtained for the system using perturbation technique that converts non-linear coupled governing partial differential equations into non-dimensional form of ordinary differential equations. Effects of variable suction velocity, rarefactions parameter and heat change parameter are analysed and discussed graphically for various values of effective physical parameter such as Grasshof number, Magnetic field parameter, Prandtl number, Permeability parameter on fluid velocity and temperature, skin friction, and heat transfer. [ABSTRACT FROM AUTHOR]

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Since the 1930s, theories of skin-friction drag from plates with rough surfaces have been based by analogy to turbulent flow in pipes with rough interiors. Failure of this analogy at small fluid velocities has frustrated attempts to create a comprehensive theory. Utilizing the concept of a self-similar roughness that disrupts the boundary layer at all scales, this investigation derives formulas for a rough or smooth plate's skin-friction coefficient and forced convection heat transfer given its characteristic length, root-mean-squared (RMS) height-of-roughness, isotropic spatial period, Reynolds number, and the fluid's Prandtl number. This novel theory was tested with 456 heat transfer and friction measurements in 32 data-sets from one book, six peer-reviewed studies, and the present apparatus. Compared with the present theory, the RMS relative error (RMSRE) values of the 32 data-sets span 0.75% through 8.2%, with only four data-sets exceeding 6%. Prior work formulas have smaller RMSRE on only four of the data-sets. [ABSTRACT FROM AUTHOR]

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article investigates MHD convective flow with variable pressure and injection/suction in a porous medium. The governing equations are modeled using partial differential equations (PDEs) in dimensional form. The PDEs describes the unsteady flow of an incompressible electrically conducting fluid are expressed for the momentum, energy and concentration of the fluid flow. Also, the PDEs were transformed to non-dimensional form using some dimensional variables. Perturbation method was used to obtain the solutions for the velocity, temperature and concentration. The non-dimensional Skin friction, Nusselt number and Sherwood number were obtained. Effects of physical parameters associated with the present study was examined and discussed. It was observed that the concentration, temperature and velocity of the fluid rises with increase in injection parameter and an opposite trend was observed when suction parameter became significant. It is found that the temperature of the fluid reduces as the Prandtl number increase. However, an opposite trend is seen for heat source/sink. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To compare and assess the coefficient of frictional resistance between nano‑coated orthodontic brackets and orthodontic archwires with conventional orthodontic brackets and archwires METHODOLOGY: In this experimental study, 128 samples were divided into 4 groups consisting of 32 orthodontic wires and brackets in each group. The samples were randomly allocated into GROUP A‑ ZNO nanoparticle coated archwires and brackets, GROUP B ZNO nanoparticle coated bracket and conventional archwire, GROUP C‑ZNO nanoparticle coated archwire and conventional bracket, and GROUP D‑ conventional archwire and bracket after positioning them on special jigs frictional resistance was studied and evaluated. Bon – Ferroni test was used for inter group comparison and one way ANOVA was used for intr‑group comparison. RESULTS: The lowest mean frictional resistance is seen with Group A (nanocoated archwire with nanocoated bracket) N = 0.3401 ± 0.420; and highest with Group D (conventional brackets with conventional archwires) N = 0.8413 ± 0.60. a significant difference in mean frictional resistance was observed between the groups (P ≤ 0.01). The frictional resistance for the groups was in the following order from lowest to highest: group A < B < C < D. CONCLUSION: The study showed decreased friction in ZNO nanoparticle coated archwires and brackets than conventional archwires and brackets. [ABSTRACT FROM AUTHOR]

The replacement ratio is an essential factor in evaluating the bearing capacity characteristics of composite foundations. This study focuses on the bearing capacity of a pervious concrete pile with different replacement ratios. The axial force, skin friction, and settlement were evaluated using a model test to assess the performance of the pervious concrete pile composite foundation. When the replacement ratio was reduced from 9.26% to 2.32%, the characteristic bearing capacity value was only 14%. Therefore, it may be unreasonable to use the settlement ratio method to evaluate this composite foundation's bearing capacity in a model test. Appropriate loading can significantly improve the bearing capacity of a pervious concrete pile composite foundation with a low replacement ratio. The pile-soil stress ratio exhibited different decreasing ranges in the later loading stage. As the load increased, the axial force of the pervious concrete piles was small and nonobvious, and the average side friction resistance of the piles in the foundation with a lower replacement ratio slowly increased. [ABSTRACT FROM AUTHOR]

The implication of a stagnation-point flow together with the influence of activation energy in a Williamson fluid, which consists of tiny particles, over an expansive plate is analyzed numerically. Conditions of convective heat and mass motion with features of irregular movement and thermal-migration of particles influenced by viscous dissipation and convective heat surface condition are checked in the study. The conversion of the model equations from the initially formulated partial derivatives to ordinary ones is implemented by similarity transformations while an unconditionally stable Runge-Kutta-Fehlberg integration plus shooting technique are then used to complete the integration. Various interesting effects of the physical parameters are demonstrated graphically and explained appropriately in order to make accurate predictions. Moreover, the accuracy of the solution is verified by comparing the values of the skin friction factor with earlier reported ones in literature under limiting constraints. It is worth mentioning that the velocity profiles flatten down as the magnitude of the magnetic field factors expands but this causes a boost in the fluid's temperature. The concentration field also appreciates with activation energy but depreciates with chemical reaction and Schmidt number. [ABSTRACT FROM AUTHOR]

The present analysis focuses on the investigation of the two-dimensional flow passing a bridge pier nearby a splitter plate in different regimes of a laminar flow. The splitter plate is T-shaped and two different cases have been studied based on the form of the splitter plate relative to the bridge pier. The analysis is implemented for steady and incompressible water flow in an open channel. The current study deals with velocity vectors, drag coefficients, lift coefficients, and skin friction. The analysis of the velocity vector gave a good indicator about the separation process and dissipation, which occurs at the splitter plate before the occurrence of these processes at the front face of the pier, especially the flow separation process. Moreover, the velocity vector gave a good image about the flow direction at two regions, the first region is located between the rear portion of the splitter plate and the frontal face of the pier, while the second region is the wake region, which is located at the downstream of the pier. Negative drag coefficient, lift coefficient, and skin friction coefficient values are obtained from the analysis. This happens due to the existence of the splitter plate that leads to the reduction of these values. [ABSTRACT FROM AUTHOR]

Strongly coupled sequences of shock waves, known as shock trains, are present in high-speed propulsion systems, where the presence of sidewalls substantially modifies the boundary layer thickness, skin friction and streamwise pressure distribution. In the present contribution, scale-resolved numerical simulations are performed on supersonic channel (infinite span) and square duct flows to evaluate the effect of sidewall confinement with and without shock trains. Comparable secondary flow vortices are observed in the duct case with and without the presence of the shock train. The absence of a separation region at the leading shock of the duct case results in lower flow deflection compared with the channel case, leading to a reduced shock strength. The principal effect of the sidewalls is to cause a shock train that is approximately twice as long and composed of a larger number of shocks. A modification of previous models, based on a momentum thickness-based blockage parameter, leads to an improved collapse of the channel and duct cases. [ABSTRACT FROM AUTHOR]

Predicting the laminar to turbulent transition is an important aspect of computational fluid dynamics because of its impact on skin friction. Traditional transition prediction methods such as local stability theory or the parabolized stability equation method do not allow for the consideration of strongly non-parallel boundary layer flows, as in the presence of surface defects (bumps, steps, gaps, etc.). A neural network approach, based on an extensive database of two-dimensional incompressible boundary layer stability studies in the presence of gap-like surface defects, is used. These studies consist of linearized Navier-Stokes calculations and provide information on the effect of surface irregularity geometry and aerodynamic conditions on the transition to turbulence. The physical and geometrical parameters characterizing the defect and the flow are then provided to a neural network whose outputs inform about the effect of a given gap on the transition through the ΔN method (where N represents the amplification of the boundary layer instabilities). [ABSTRACT FROM AUTHOR]

This research investigates the flow of stagnation point magnetohydrodynamic (MHD) and heat transfer along the stretched sheet in the existence of radiation and slip effects. With the help of similarity variables, the governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs). The BVP4C technique in Matlab function has been used to simplify the governing ODEs. The numerical outcomes for temperature and velocity profiles, coefficient of skin friction and Nusselt Number have been achieved and matched with the findings in literature. The findings are compared to previously reported results. In addition, the impacts of numerous related parameters on the profiles of velocity and temperature are shown, and the results of every related parameter are presented using graphs. The velocity profile decreases as the magnetic force, suction, and permeability parameters rise. [ABSTRACT FROM AUTHOR]

Worksites at height require the protection of workers during both movement and task performance. The rope access technique involves the simultaneous use of working and backup textile rope systems. Currently, kernmantle ropes are most often used in conjunction with mechanisms that move along them and lock at the right moment. However, this mode of operation has a destructive effect on the rope. Ropes must therefore meet a number of specific requirements, one of the most important of which is sheath slippage. The paper presents a method for testing this parameter based on the requirements of EN standards, including the design and implementation of a test stand and a method for the verification of its operation. Test results for 11 types of ropes are presented and discussed. The paper also provides some guidelines for conducting tests. [ABSTRACT FROM AUTHOR]

Cemented paste backfill (CPB) plays an increasingly important role in the mining industry due to its operational and environmental benefits. CPB is placed in the mined-out stope to form a self-supporting structure. The strength and stability of the CPB is of great concern in its engineering applications. Indeed, CPB must remain stable during the extraction of adjacent stopes to ensure the safety of the mine operations. Although significant research has been conducted on the shear properties of CPB, there are limited studies on its post-failure behavior, in particular the yield characteristics of CPB. This paper presents the finding on the post-peak and yield property of CPB. The study is conducted on three cemented contents and six stress intervals based on the mining practice and field study. The results show that CPB exhibits dilative behavior under strain softening and contractive property under strain hardening conditions. Our study demonstrates that pure frictional resistance could exceed the cohesion strength at high stress levels. [ABSTRACT FROM AUTHOR]

In the current study, a comparative analysis of two-dimensional heat transfer by the free convective flow of non-Newtonian Casson and Carreau fluid in electro-conductive polymer on the outside surface of a horizontal circular cylinder under slip and radial magnetic field effects is regarded. The Casson and Carreau fluid model formulation were first developed for the problem of the boundary layer of the horizontal circular cylinder and by using non-similarity transformations, the combined governing partial differential equations are translated into ordinary differential equations. The differential equations obtained are resolved by the Keller Box Method (KBM). The impact of the key parameters, the rate of heat transfer and skin friction is evaluated through graphs and tables. The result reveals that an increase in magnetic number decreases the velocity field of both Casson and Carreau fluid also Casson fluid is higher values when compared to Carreau fluid in variation of magnetic number. [ABSTRACT FROM AUTHOR]

Objectives: Minimizing the frictional force between orthodontic wire and brackets is imperative to safely obtain a more favorable result by applying lower loads. Several methods have been proposed for this purpose such as changing the wire shape/size, changing the bracket design, and coating wires with different materials. This study aimed to assess the effect of zirconium oxide (ZrO2) nano-coating on frictional resistance of three types of orthodontic wires. Materials and Methods: This in vitro, experimental study evaluated 42 pieces of nickel-titanium (NiTi), stainless steel (SS), and beta-titanium (TMA) orthodontic wires, and 42 maxillary canine brackets. The samples were divided into six groups with and without ZrO2 nano-coating. The nano-coating was applied on the wires using the sol-gel technique. The presence of ZrO2 nano-coating was evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The surface roughness of the samples was evaluated using atomic force microscopy (AFM). The brackets and wire had a 5° angle relative to each other. The static and kinetic friction of the samples were evaluated in the presence of artificial saliva and occlusogingival movements in a universal testing machine. Data were analyzed by the Shapiro--Wilk's test, one-way ANOVA, Kruskal--Walli's test, Mann--Whitney U test, independent t-test, and Tukey's test. Results: ZrO2 nano-coating was only observed on TMA wires. The surface roughness of coated NiTi and SS wires had no significant difference from that of non-coated wires (P > 0.05). However, this difference was significant for TMA wires with and without the coating (P < 0.05). The static and kinetic friction were not significantly different between wires with and without coating (P > 0.05). Conclusions: ZrO2 nano-coating could only be applied on TMA wires, and had no significant efficacy for reduction of static or kinetic friction of TMA wires. [ABSTRACT FROM AUTHOR]

This work reports the heat and mass transfer of the 2-D MHD flow of the Casson and Williamson motions under the impression of non-linear radiation, viscous dissipation, and thermo-diffusion and Dufour impacts. The flow is examined through an extending zone along with inconsistent thickness. The partial differential equations are extremely nonlinear and lessen to ODEs throughout of the appropriate similarity transformation. The system of nonlinear and coupled ODEs is handled applying a numerical approach with shooting procedure. Numerical solutions for momentum and energy descriptions are deliberated through graphs and tabular form for the impacts of magnetic parameter, Soret and Dufour variables, momentum power index variable, Schmidt number, wall thickness variable, without dimensions velocity slip, heat jump and mass jump variable. Outcomes illustrate that the momentum, temperature, and concentration transfer of the laminar boundary layers of equally non-Newtonian liquid motions are non-consistent. A comparison made with the existing literature which shows an good agreement and confidence of the present outcomes. It shows that Casson parameter restricted the skin friction, local heat and mass transfer while λ enhanced the skin friction, local heat and mass transfer. Velocity slip constant decreases the skin friction, local heat and mass transfer and a similar observation for thermal slip constant while an opposite phenomena for the solutal slip constant. [ABSTRACT FROM AUTHOR]

This systematic review was aimed to test the null hypothesis that coating of orthodontic wires with nanoparticles does not affect the frictional properties at bracket--wire interface. Electronic database searches were performed up to September 2020. In vitro studies were considered for reviewing process. Study selection, data extraction, risk of bias assessment was performed during reviewing process. Only qualitative analyses of included literature were done due to the presence of heterogeneity among the studies. Out of 1,068 retrieved records, nine studies satisfied the inclusion criteria and included in this review. Studies were assessed at low risk to high risk of bias according to certain parameters. Wide variety of nanoparticles were used for surface coating of orthodontic wires of variable sizes, shapes, and materials like stainless steel, NiTi, and TMA and placed into the slots of different types of orthodontic brackets to evaluate the alteration in frictional and other mechanical properties. Most of the studies clearly indicate that coating with nanoparticles decreases the friction between wire and bracket interface under specified in vitro conditions. Furthermore, among the nine included studies, only two considered evaluation of effect of coated brackets on frictional and other mechanical properties and results were heterogeneous. The null hypothesis is rejected and it is concluded that the wires coated with nanoparticles might offer a novel opportunity to substantially reduce frictional resistance at bracket--wire interface during tooth movement. Further studies are necessary to strengthen the evidence regarding effect of coated brackets on frictional properties. [ABSTRACT FROM AUTHOR]

The prediction of the total resistance occurred during operation of a floatplane on the water surface is an important aspect in developing the floater as well as the engine power required. Theoretically, the trim angle of the floater may affect the total resistance. This paper intends to find the optimal trim angle for the take-off operation using the computational fluid dy-namics (CFD) software. The floater set up under a fixed trim angle includes 2°, 5° and 10° taken in simulation at five different speeds between 9.21m/s and 15.87m/s. In one case of 2° trim angle, the floater model test has been carried out in a tow tank laboratory to validate the accuracy of the numerical result. Comparison of both results has a good fit with an average error of 2.27%. In the final simulation results, the optimum trim angle is 5°, which produces the total resistance less than 2° and 10° of the trim angle with average differences of 9.21% and 50.46% for all speeds, respectively. [ABSTRACT FROM AUTHOR]

The investigation of shock wave boundary layer interaction (SWBLI) and the prediction of the associated flow field and surface property variation are essential elements in designing scramjet engine. Therefore, the present study on SWBLI is carried out numerically on a two-dimensional scramjet intake model. The effect of various free-stream and wall conditions on the surface pressure, the skin friction coefficient and performance of the intake model are analysed. It is observed that increase in the Mach number and the free-stream temperature reduces the size of the separation zones within intake. The larger separation zones are observed by increasing the wall temperature. It is noted that the behaviour of SWBLI at ramp junction and isolator inlet are dissimilar and the ratio of free-stream stagnation temperature to wall temperature does not govern the parameter for separation bubble at isolator inlet. The present investigations recommend that the Mach number has significant influence while the wall temperature and the free-stream temperature have a little effect on the performance of the intake. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the stagnation point flow of Maxwell micropolar fluid flow over a Riga plate. Micropolar fluid flows over the Riga plate were used to create the mathematical model. The system of partial differential equations is created using the momentum equation and the micro inertia theory to accomplish the boundary layer approximation. Through appropriate similarity transformations, nonlinear partial differential equations are transformed into dimensionless nonlinear ordinary differential equations. This system solved the numerical scheme via the BVP4C method. The effects of involving physical parameters like dimensionless parameter, modified Hartman number, material parameter, slip condition σs, viscoelastic parameter δm and Soret coefficient ST are shown through graphs and numerical results. The physical quantities such as Skin friction, local Nusselt number, and local Sherwood number are shown in tables. R increases when the dimensionless parameter, Material parameter K and Slip condition σs increase, while R decreases with the Modified Hartman number Z and viscoelastic parameter δm increase. [ABSTRACT FROM AUTHOR]

Theoretical investigation of variable mass diffusivity, thermal conductivity, and viscosity on unsteady squeezed flow of dissipative Casson fluid is presented. Physically, for any effective heat and mass transfer process, a proper account of thermophysical properties in such a system is required to attain the desired production output. The magnetized free convective flow of unsteady Casson fluid encompassing Joule dissipation, radiation, and chemical reactive influence is induced as a result of squeezing property. The governing model assisting the magnetized flow is formulated and transformed via an appropriate similarity transformation. The resulting set of ordinary differential equations is solved numerically using Chebyshev based Collocation Approach (CCA). However, variable viscosity, thermal conductivity, and mass diffusivity effects are seen to diminish the fluid flow velocities, temperature, and concentration respectively along with the lower plate. Heat and mass transfer coefficient, skin friction downsized to an increasing value of variable thermal and mass diffusivity parameters while variable viscosity pronounces the skin friction coefficient. Furthermore, the present analysis is applicable in polymer processing, such as injection molding, extrusion, thermoforming among others. [ABSTRACT FROM AUTHOR]

This investigation describes the hydromagnetic flow of gravity-driven couple stress hybrid nanofluid past a heated plate. The carbon nanotubes (CNTs) are used to characterize the hybrid nanofluid. The heated plate is placed vertically with an application of homogenous-heterogeneous reactions to the assumed flow system. The homogeneous reaction governs by isothermal cubic autocatalytic kinetics while the heterogeneous reaction governs by the first order kinetics. For current study the couple stress hybrid nanofluid is presumed to be conducted electrically with impact of non-uniform magnetic effects. An appropriate set of dimensionless quantities has employed to governing equations and then has solved by homotopy analysis method. The influence of emerging parameters encountered in this work has discussed in detail with the help of graphs. In this study it has examined that, flow of fluid reduces with upsurge in magnetic parameter and volumetric concentrations, whereas thermal and concentration characteristics augment with increase in volumetric concentrations. Moreover, growth in Prandtl number leads to a reduction in thermal characteristics and growth in Schmidt number result a reduction in concentration profile. The impact of various emerging parameters has also studied numerically upon physical quantities. It has established that, with augmentation in values of buoyancy parameter there is a growth in the values of skin friction. A comparison has also carried out between current and established results with a fine agreement in both results. [ABSTRACT FROM AUTHOR]

This article presents the implementation of a numerical solution of bioconvective nanofluid flow. The boundary layer flow (BLF) towards a vertical exponentially stretching plate with combination of heat and mass transfer rate in tangent hyperbolic nanofluid containing microorganisms. We have introduced zero mass flux condition to achieve physically realistic outcomes. Analysis is conducted with magnetic field phenomenon. By using similarity variables, the partial differential equation which governs the said model was converted into a nonlinear ordinary differential equation, and numerical results are achieved by applying the shooting technique. The paper describes and addresses all numerical outcomes, such as for the Skin friction coefficients (SFC), local density of motile microorganisams (LDMM) and the local number Nusselt (LNN). Furthermore, the effects of the buoyancy force number, bioconvection Lewis parameter, bioconvection Rayleigh number, bioconvection Pecelt parameter, thermophoresis and Brownian motion are discussed. The outcomes of the study ensure that the stretched surface has a unique solution: as Nr (Lb) and Rb (Pe) increase, the drag force (mass transfer rate) increases respectively. Furthermore, for least values of Nb and all the values of Nt under consideration the rate of heat transfer upsurges. The data of SFC, LNN, and LDMM have been tested utilizing various statistical models, and it is noted that data sets for SFC and LDMM fit the Weibull model for different values of Nr and Lb respectively. On the other hand, Frechet distribution fits well for LNN data set for various values of Nt. [ABSTRACT FROM AUTHOR]

Impacts of heat source/sink and radiation on fluid flow and heat transfer past a permeable exponentially stretching/shrinking Riga plate were studied in this work. The governing partial differential equations were reduced to higher-order nonlinear ordinary differential equations using a suitable similarity transformation. The reduced equations are then numerically solved using the MATLAB software boundary value problem solver. The behavior of the skin friction coefficient and heat transfer is visually represented using numerical results. According to the findings, the modified Hartmann number significantly affects the heat transfer rate and the skin friction coefficient. The results also showed that the modified Hartmann number could be used as a controller for the heat transfer rate in case of radiation and heat source/sink occurrence. [ABSTRACT FROM AUTHOR]

A three-dimensional model of viscous magnetohydrodynamic Newtonian fluid flow bounded by an exponentially stretching plate is developed. The fluid velocity, temperature and concentration are assumed to be distributed exponentially. With the help of non-similarity transformation, the partial differential governing equations are converted to ordinary differential equations and then the problem is solved using the bvp4c MATLAB program. The collective results are compared with those of earlier studies in a limiting case and found to be in good agreement. The numerical results on the Newtonian fluid flow (velocity profile and skin friction coefficient), the changes of the fluid temperature (temperature profile and local Nusselt number), and the differences of fluid mass (concentration profile and local Sherwood number) are presented graphically. The fluid velocity and the skin friction coefficient increase with the increment of the mixed convection parameter and decrease with the increment of the magnetic field parameter. On the other hand, the heat (local Nusselt number) and mass (local Sherwood number) transfer increases with the increment of the stretching parameter. [ABSTRACT FROM AUTHOR]

This study addresses numerical solutions of a magnetohydrodynamic Casson fluid considering the temperature and concentration gradients. First, two-dimensional partial differential governing equations (PDEs) are considered to develop a mathematical model. Next, similarity variables are applied to modify the PDEs into ordinary differential equations (ODEs). The converted equations are numerically solved with the help of the bvp4c Matlab program. Impacts of the magnetic field and shrinking parameter on the skin friction, Nusselt number and Sherwood number along with the profiles of velocity, temperature, and concentration are displayed through graphs. Finally, the obtained results are validated by comparing with previously published ones. Furthermore, stability analysis is made due to dual numerical solutions to select the stable one, and the first solution is considered stable. [ABSTRACT FROM AUTHOR]

The Wall-modeled Large-eddy Simulation (WMLES) methods are commonly accompanied with an underprediction of the skin friction and a deviation of the velocity profile. The widely-used Improved Delayed Detached Eddy Simulation (IDDES) method is suggested to improve the prediction of the mean skin friction when it acts as WMLES, as claimed by the original authors. However, the model tested only on flow configurations with no heat transfer. This study takes a systematic approach to assess the performance of the IDDES model for separated flows with heat transfer. Separated flows on an isothermal wall and walls with mild and intense heat fluxes are considered. For the case of the wall with heat flux, the skin friction and Stanton number are underpredicted by the IDDES model however, the underprediction is less significant for the isothermal wall case. The simulations of the cases with intense wall heat transfer reveal an interesting dependence on the heat flux level supplied; as the heat flux increases, the IDDES model declines to predict the accurate skin friction. [ABSTRACT FROM AUTHOR]

Pipe flow has been a challenge that gave rise to investigations on turbulence—long before turbulence was discerned as a research problem in its own right. The discharge of water from elevated reservoirs through long conduits such as for the fountains at Versailles suggested investigations about the resistance in relation to the different diameters and lengths of the pipes as well as the speed of flow. Despite numerous measurements of hydraulic engineers, the data could not be reproduced by a commonly accepted formula, not to mention a theoretical derivation. The resistance of air flow in long pipes for the supply of blast furnaces or mine air appeared even more inaccessible to rational elaboration. In the nineteenth century, it became gradually clear that there were two modes of pipe flow, laminar and turbulent. While the former could be accommodated under the roof of hydrodynamic theory, the latter proved elusive. When the wealth of turbulent pipe flow data in smooth tubes was displayed as a function of the Reynolds number, the empirically observed friction factor served as a guide for the search of a fundamental law about turbulent skin friction. By 1930, a logarithmic "wall law" seemed to resolve this quest. Yet pipe flow has not been exhausted as a research subject. It still ranks high on the agenda of turbulence research—both the transition from laminar to turbulent flow and fully developed turbulence at very large Reynolds numbers. [ABSTRACT FROM AUTHOR]

The role of nanofluids is of fundamental significance in the cooling process of small electronic devices including microchips and other associated gadgets in microfluidics. With such astounding applications of nanofluids in mind, it is intended to examine the flow of magnetohydrodynamic nanofluid comprising a novel combination of multi-walled carbon nanotubes and engine oil over a stretched rotating disk. The concentration equation is modified by considering the autocatalytic chemical reaction. The succor of the bvp4c numerical technique amalgamated with the response surface methodology is secured for the solution of a highly nonlinear system of equations. The sensitivity analysis is performed using a response surface methodology. The significant impacts of the prominent arising parameters versus involved fields are investigated through graphical illustrations. It is observed that the skin friction coefficient and local Nusselt number are positively sensitive to nanoparticle volume fraction while it is positively sensitive to the suction parameter. It is negatively sensitive to the Magnetic parameter. The skin friction coefficient is negatively sensitive to all input parameters. [ABSTRACT FROM AUTHOR]

The present study experimentally determines the transitional Reynolds number range for plane channel flow and characterizes its transitional state. The pressure along the channel is measured to determine the skin friction coefficient as function of Reynolds number from the laminar state, through the transitional region into the fully turbulent state. The flow structure was studied through flow visualisation which shows that as the Reynolds number increases from the laminar state the transitional region starts showing randomly occurring turbulent spots. With increasing Reynolds number the spots shift into oblique patches and bands of small scale turbulence that form across the channel width, together with large-scale streaky structures found in areas between the turbulent regions. An image analysing technique was used to determine the intermittency factor, i.e. the turbulence fraction in the flow, as function of Reynolds number. It is found that the skin friction coefficient reaches its turbulent value before the flow is fully turbulent (the intermittency factor is still below one). This suggests that the observed streaky structures in non-turbulent regions contribute to the enhancement of the wall-normal transfer of momentum. Also above the Reynolds numbers where the turbulent skin friction coefficient has been established large-scale features consisting of irregular streaky structures are found. They have an oblique shape similar to the non-turbulent and turbulent patches in the transitional flow indicating that the transition process is not fully complete even above the Reynolds number where the skin friction reaches its turbulent level. [ABSTRACT FROM AUTHOR]

The determination of the stress distribution around driven piles in soft clays constitutes a complex problem. The stress distribution is affected by a range of factors such as soil permeability, soil strength, sensitivity, remoulding, distance from adjacent piles and number of piles. The mechanisms of pile installation and subsequent consolidation are investigated by considering that pile installation may be represented by the expansion of a long vertical cylindrical cavity. The stress paths followed by typical soil elements at the soil–pile interface are analyzed by means of the theoretical relationships obtained during the undrained expansion of a cylindrical cavity in soft cohesive soils and modified to take into account the severe remoulding caused by pile installation. It is shown that the shaft resistance of driven piles may be calculated by considering either a drained stress path or an effective stress path during undrained loading. It is also shown that soft clay remoulding caused by pile driving is a major factor that must be taken into account for a reasonable estimation of the limiting skin friction. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated thermally stratified MHD flow of an Oldroyd-B fluid over an inclined stretching surface in the presence of heat generation/absorption. Similarity solutions for the transformed governing equations are obtained. The reduced equations are solved numerically using the Runge–Kutta Fehlberg method with shooting technique. The influences of various involved parameters on velocity profiles, temperature profiles, local skin friction, and local Nusselt number are discussed. Numerical values of local skin friction and local Nusselt number are computed. The significant outcomes of the study are that the velocity decreases when the radiation parameter R d is increased while the temperature profile is increased for higher values of radiation parameter R d in case of opposing flow, moreover, growth in Deborah number β 2 enhance the velocity and momentum boundary layer. The heat transfer rate is decrease due to magnetic strength but increase with the increased values of Prandtl and Deborah numbers. The results of this model are closely matched with the outputs available in the literature. [ABSTRACT FROM AUTHOR]

Aims & Objectives: The aim of the study was to evaluate and compare dimensional accuracy, surface characteristics and load deflection attributes of SS wires sourced from six different commercial houses. Materials & Methods: 0.019" x 0.025" SS wire samples were divided into 6 groups and evaluated and compared for the aforementioned properties. Dimensional accuracy, surface roughness, frictional resistance, load deflection rate and ultimate tensile strength were evaluated and compared. Results: Dimensional accuracy did not vary significantly. Surface Profilometry proved 3M Unitek (Group 1) to be the wire with least irregularities. According to SEM, Modern Orthodontics (Group 6) and 3M Unitek (Group 1) in terms of 'Sa' and 'Sq' respectively had the smoothest surface finish. SS wires sourced from G&H Orthodontics (Group 2) exhibited least frictional resistance. Load deflection rates varied for all the groups for all three parameters under the study. UTS was best for SS wires sourced from Rabbit Force Orthodontics (Group 5). Conclusion: No wire from a single commercial house excels in all the parameters that were evaluated, each one having its aces and minuses. [ABSTRACT FROM AUTHOR]

The purpose of present paper is to analyze the Soret and Dufour effects on an unsteady magneto hydrodynamic oscillatory flow of radiative, visco-elastic fluid through an inclined channel filled with saturated porous medium with nonuniform wall temperature in presence of first-order chemical reaction. The governing dimensionless momentum equation coupled with the energy and mass diffusion equations are solved analytically. The expressions for velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number are obtained and are analyzed graphically for various values of the dimensionless flow parameters. [ABSTRACT FROM AUTHOR]

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The flow has been made by considering variable temperature and radiation effects for the magnetohydrodynamic viscoelastic fluid past a moving vertical plate in a porous medium. Chemical reaction and concentration have been taken into account. The governed mathematical statement is handled analytically by perturbation technique. The main view of this research is to investigate the effects of parameters and numbers in the problem on fluid flow, thermal boundary and concentration profiles. The velocity profile has been reduced by increasing the magnetic parameter due to the Lorentz force in the opposite direction of flow. Temperature profile is increased by rising thermal radiation and concentration distribution is decreased by enhancing the chemical reaction and Schmidt number. The Schmidt number represents the relative ease of the molecular momentum and mass transfer and it is very important in multiphase flows. The effect of increasing values of the Schmidt number is to reduce the momentum boundary layer and this leads to the thinning of the diffusion layer. Furthermore, at the end of this paper the effects of different parameters on skin friction coefficient and local Nusselt number are investigated. [ABSTRACT FROM AUTHOR]

The main features of present numerical model is to explore and compare the behavior of simple and hybrid nanoparticles, which were allowed to move on a spreading sheet. The effect of magnetic dipole on hybrid nanofluid flow is considered. A magnetic dipole combined with hybrid nanofluid plays a vital role in controlling the momentum and thermal boundary layers. In view of the impacts of a magnetic dipole on the simple and hybrid nanofluids, steady, laminar and boundary layer flow of C u / H 2 O and C u − A l 2 O 3 / H 2 O are characterized in this analysis. The governing equations of flow problem are diminished to ordinary differential equation (ODE's) by using similarity approach. For the numerical solution of the nonlinear ODE's, Runge Kutta order 4th technique has been executed. The impact of various physical constraints, such as volume friction, viscous dissipation, Prandtl number and so on have been sketched and briefly discussed for velocity and temperature profile. In this work, some vital characteristics such as skin friction, Curie temperature and local Nusselt number are chosen for physical and numerical analysis. It has been noted that the hybrid nanofluid is more efficient in thermal conduction due to its strong thermal characteristics as compared to simple nanofluid. From results, it is also observed that the turbulence of fluid flow can be controlled through magnetic dipole. [ABSTRACT FROM AUTHOR]

The shape of the needle tip that is currently used in the medical field is a "lancet point," which is a diagonally cut cylindrical pipe, further cut on both sides. The shape of the needle shank is typically cylindrical. In this paper, tip and shank shapes that differ from the standard shape are experimentally investigated for the purpose of reducing puncture resistance. Microneedles of various cross-sectional shapes, such as polygonal and star-like, were fabricated using stereo laser lithography. Before the needle penetrates the skin, sharp edges at the needle tip may be effective to generate a stress concentration on the skin, inducing a skin fracture. After the needle penetrates the skin, corners in the cross section of the needle shank may effectively reduce the frictional resistance because the contact area between the skin and needle is limited at the corners. A needle insertion experiment was conducted against an artificial skin made of polydimethylsiloxane. The puncture resistance decreased respectively for the circular needle, polygonal needle, and star-shaped needle. For the star-shaped needles, the maximum resistance decreased as the number of corners (N) decreased. For the polygonal needle, the maximum resistance increased as N increased from 3 to 5; however, there was no observable difference for N from 6 to 8. The experimental results show that a triangular star-shaped microneedle is the most effective in reducing the puncture resistance. [ABSTRACT FROM AUTHOR]

The time-dependent barrier passage of two-dimensional non-Ohmic damping system is studied in the framework of statistical Langevin reactive dynamics. The stationary transmission coefficient is found to be a nonmonotonic function of the exponent δ which reveals an intrinsic effect of the friction’s non-Markovian character on the two-dimensional reactive process; the coupling between nonreactive and reactive modes results in an optimal path for the reactant in all cases of non-Ohmic friction. A big net flux resulted from the less barrier recrossing behavior in the two-dimensional non-Ohmic friction case. [ABSTRACT FROM AUTHOR]