Impacts of Newtonian heating, variable fluid properties and Cattaneo–Christov model on MHD stagnation point flow of Walters’ B fluid induced by stretching surface

2020 ◽  
Vol 31 (09) ◽  
pp. 2050125
Author(s):  
Ahmed A. Afify ◽  
Nasser S. Elgazery
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Temperature Fields ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Opposite Behavior ◽  
The Mathematical Model ◽  
Walters B Fluid

MHD viscoelastic (Walters’-B) fluid flow close to the stagnation point region along an extending plate with the changeable fluid properties’ influences has been debated. Heat transfer’s features are scrutinized via Cattaneo–Christov (CC) theory. The mathematical model for the physical problem is tackled numerically via Chebyshev pseudospectral (CPS) technique. The existing outcomes are supported by recent research and have acquired a suitable agreement. The numerical outcomes reveal that temperature fields are more pronounced for Fourier’s law case. Further, the opposite behavior is noticed with the heat transfer rate. Higher values of the conjugate parameter result in an increment of the heat transfer rate and temperature field. Fluid flow’s features, as well as physical quantities, are substantially varied via variable fluid properties.

Non-axisymmetric Homann stagnation point flow and heat transfer past a stretching/shrinking sheet using hybrid nanofluid

2020 ◽  
Vol 30 (10) ◽  
pp. 4583-4606 ◽  
Author(s):  
Najiyah Safwa Khashi’ie ◽  
Norihan Md Arifin ◽  
Ioan Pop ◽  
Roslinda Nazar ◽  
Ezad Hafidz Hafidzuddin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Strain Rate ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Hybrid Nanofluid ◽  
Ambient Fluid ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose This paper aims to scrutinize the analysis of non-axisymmetric Homann stagnation point flow and heat transfer of hybrid Cu-Al2O3/water nanofluid over a stretching/shrinking flat plate. Design/methodology/approach The similarity transformation which fulfils the continuity equation is opted to transform the coupled momentum and energy equations into the nonlinear ordinary differential equations. Numerical solutions which are elucidated in the tables and graphs are obtained using the bvp4c solver. Findings Non-unique solutions (first and second) are feasible for both stretching and shrinking cases within the specific values of the parameters. First solution is the physical/real solution based on the execution of stability analysis. An upsurge of the ratio of the ambient fluid strain rate to the plate strain rate can delay the boundary layer separation, whereas a boost of the ratio of the ambient fluid shear rate to the plate strain rate only accelerates the separation of boundary layer. The heat transfer rate of hybrid nanofluid is greater for the stretching case than the shrinking case. However, for the shrinking case, the heat transfer rate intensifies with the increment of the copper (Cu) nanoparticles volume fraction, whereas a contrary result is found for the stretching case. Originality/value The present numerical results are original and new. It can contribute to other researchers on electing the relevant parameters to optimize the heat transfer process in the modern industry, and the right parameters to generate non-unique solution so that no misjudgment on flow and heat transfer features.

Near-Wall RANS Modelling in LES of Heat Transfer in Backward-Facing Step Flows Under Conditions of Constant and Variable Fluid Properties

2010 ◽  
Author(s):  
S. Jakirlic´ ◽  
B. Kniesner
Keyword(s):  
Heat Transfer ◽  
Temperature Fields ◽  
Large Temperature ◽  
Backward Facing Step ◽  
Local Flow ◽  
Wall Heating ◽  
Variable Fluid Properties ◽  
Fluid Properties ◽  
Flow Domain ◽  
Near Wall

Two backward-facing step (BFS) flow configurations associated with the heat transfer under the conditions of constant and variable fluid properties were investigated computationally by means of LES and a zonal Hybrid LES/RANS (HLR) method. The latter scheme couples a RANS (Reynolds-Averaged Navier-Stokes) model with large-eddy simulation (LES) within a two-layer framework. A differential near-wall eddy-viscosity model resolves the wall layer and the LES model the remainder of the flow domain. As an introductory heat-transfer case a fully-developed channel flow at Re number Rem = 24000 (DNS: Abe et al., 2004) was computed. In both presently investigated BFS cases the flow is subjected to increasingly enhanced wall heating. Whereas the first considered case (ReH = 28000, ER = 1.25), treated experimentally by Vogel and Eaton (1985) - reference LES is due to Keating et al., 2004, deals with a passive scalar transport, the high-intensity heat flux introduced into the flow domain through the step wall in the second investigated configuration (ReH = 5540, ER = 1.5; reference LES by Avancha and Pletcher, 2002; corresponding isothermal experiment by Kasagi and Matsunaga, 1995) leads to large temperature gradients causing a strong variation of the flow properties. An important feature of the latter flow is a substantial increase of the friction coefficient magnitude with the wall heating intensification in both the flow reversal and recovery region, associated with the local flow acceleration in the immediate wall vicinity. The results obtained by the present simulations with respect to the mean velocity and temperature fields, friction factor and Stanton number variations follow closely the reference experimental and LES databases.

scholarly journals A Resolved Eulerian–Lagrangian Simulation of Fluidization of 1204 Heated Spheres in a Bed With Heat Transfer

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Zhi-Gang Feng ◽  
Eid S. Alatawi ◽  
Adam Roig ◽  
Cenk Sarikaya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Fluid Velocity ◽  
Jet Flow ◽  
Uniform Flow ◽  
Temperature Fields ◽  
Lagrangian Simulation ◽  
Simulation And Experiment ◽  
Ib Method

A resolved Eulerian–Lagrangian numerical approach is used to study the heat transfer of 1204 heated spheres fluidized in a slit bed. This approach uses a direct numerical simulation combined with the immersed boundary method (DNS-IB). Pan et al. (2002, “Fluidization of 1204 Spheres: Simulation and Experiment,” J. Fluid Mech., 451, pp. 169–192) studied the fluidization of 1204 spheres by a uniform flow without heat transfer using a fictitious domain-based DNS. The focus of this study is placed on the heat transfer between the heated spheres and fluid and also the fluidization by a jet flow. In the DNS-IB method, fluid velocity and temperature fields are obtained by solving the modified momentum and heat transfer equations, which result from the presence of heated spheres in the fluid. Particles are tracked individually and their velocities and positions are solved based on the equations of linear and angular motions; particle temperature is assumed to be a constant. The momentum and heat exchange between a particle and the surrounding fluid at its surface are resolved using the IB method with the direct forcing scheme. By exploring the rich data generated from the DNS-IB simulations, we are able to obtain statistically averaged fluid and particle velocity as well as particle heat transfer rate in a fluidized bed. Our results on the pressure drop and bed height are compared to the results of Pan et al. (2002, “Fluidization of 1204 Spheres: Simulation and Experiment,” J. Fluid Mech., 451, pp. 169–192), which show good agreements. The case of the fluidization of 1204 spheres by a jet flow has also been studied and compared against the case of the fluidization by a uniform flow. The flow structures, drag, and heat transfer rate of two spheres placed along flow directions have been studied to understand the influence of a neighboring sphere. Results show that the trailing sphere has an insignificant effect on the leading sphere when it comes to the drag and heat transfer rate. On the contrary, the leading sphere can reduce the drag and heat transfer rate of the trailing sphere by more than 20% even when the two spheres are separated by six diameters. This demonstrates the need of a fully resolved DNS in accurately modeling dense particulate flows where a particle could be surrounded by multiple neighboring particles.

scholarly journals Stagnation Point Flow of a Nanofluid toward an Exponentially Stretching Sheet with Nonuniform Heat Generation/Absorption

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
A. Malvandi ◽  
F. Hedayati ◽  
G. Domairry
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Heat Generation ◽  
Transfer Rate ◽  
Stretching Sheet ◽  
Stagnation Point Flow ◽  
Brownian Diffusion ◽  
Exponentially Stretching Sheet ◽  
Exponentially Stretching

This paper deals with the steady two-dimensional stagnation point flow of nanofluid toward an exponentially stretching sheet with nonuniform heat generation/absorption. The employed model for nanofluid includes two-component four-equation nonhomogeneous equilibrium model that incorporates the effects of Brownian diffusion and thermophoresis simultaneously. The basic partial boundary layer equations have been reduced to a two-point boundary value problem via similarity variables and solved analytically via HAM. Effects of governing parameters such as heat generation/absorption λ, stretching parameter ε, thermophoresis , Lewis number Le, Brownian motion , and Prandtl number Pr on heat transfer and concentration rates are investigated. The obtained results indicate that in contrast with heat transfer rate, concentration rate is very sensitive to the abovementioned parameters. Also, in the case of heat generation , despite concentration rate, heat transfer rate decreases. Moreover, increasing in stretching parameter leads to a gentle rise in both heat transfer and concentration rates.

scholarly journals Non-linear radiation influence on oblique stagnation point flow of Maxwell fluid

2018 ◽  
Vol 64 (4) ◽  
pp. 420 ◽  
Author(s):  
Abuzar Ghaffari ◽  
T. Javed ◽  
I. Mustafa
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Prandtl Number ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Maxwell Fluid ◽  
Stagnation Point Flow ◽  
Non Linear ◽  
Linear Radiation

Non-linear thermal radiation effects on non-aligned stagnation point flow of Maxwell fluid have been carried out in the present investigation. It is observed that the non-linear radiation augments the temperature and heat transfer rate. This physical phenomenon is translated into a system of partial differential equations (PDEs). After useful transformation, these non-linear constitutive equations are transformed into a system of ordinary differential equations (ODEs) and interpreted numerically by means of parallel shooting technique. Effects of pertinent parameters on flow and heat transfer are elaborated through tables and graphs. It is observed that radiation and surface heating enhance the rate of heat transfer, however Prandtl number has inverse relation with thermal boundary layer thickness. It has been observed that for increasing Prandtl number, heat transfer rate enhances. The detailed discussion of heat transfer rate is also presented in this study. Flow pattern is judged through streamlines graphs. It is also observed that oblique stagnation point flow behaves like orthogonal stagnation point flow, when free stream velocity is very large as compared to stretching velocity.

scholarly journals Effects of Radiation and Eckert Number on MHD Flow with Heat Transfer Rate Near a Stagnation Point Over a Non-Linear Vertical Stretching Sheet

2020 ◽  
Vol 25 (1) ◽  
pp. 27-36
Author(s):  
O.J. Fenuga ◽  
A.R. Hassan ◽  
P.O. Olanrewaju
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stretching Sheet ◽  
Velocity Ratio ◽  
Physical Nature ◽  
Mhd Flow ◽  
Eckert Number ◽  
Effects Of Radiation

AbstractThis work investigates the effects of radiation and Eckert number on an MHD flow with heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the sixth order Runge-Kutta method with shooting technique. Tabular and graphical results are provided to examine the physical nature of the problem. Heat transfer rate at the surface decreases with radiation, Eckert number and as radiation increases, the flow temperature also increases for velocity ratio parameters ɛ <1 and ɛ >1.

scholarly journals Mixed Convection in MHD Flow and Heat Transfer Rate Near a Stagnation-Point on a Non-Linear Vertical Stretching Sheet

2020 ◽  
Vol 25 (1) ◽  
pp. 37-51 ◽  
Author(s):  
O.J. Fenuga ◽  
A.R. Hassan ◽  
P.O. Olanrewaju
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stretching Sheet ◽  
Mhd Flow ◽  
Surface Drag ◽  
Flow Parameters ◽  
Flow And Heat Transfer

AbstractThis work investigates the mixed convection in a Magnetohydrodynamic (MHD) flow and heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the fourth order Runge-Kutta method with shooting technique. The influence of pertinent flow parameters on velocity, temperature, surface drag force and heat transfer rate are computed and analyzed. Graphical and tabular results are given to examine the nature of the problem. The heat transfer rate at the surface increases with the mixed convection.

scholarly journals Magnetohydrodynamic mixed convection in a nanofluid filled tubular enclosure

2020 ◽  
Vol 4 (1) ◽  
pp. 19-24
Author(s):  
Mohammad Mokaddes Ali
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Temperature Fields ◽  
Convection Flow ◽  
Governing Equations ◽  
Convection Regime ◽  
Special Cases ◽  
Flow Domain

Mixed convection flow in a tubular enclosure filled with nanofluid in the presence of a magnetic field is numerically investigated in the present study. The bottom and top curved wall of the enclosure are respectively kept isothermally hot and cool while the remaining walls are insulated. The governing equations are formulated based on Boussinesq assumptions and solved with finite element method. The computation is carried out for mixed convection regime (0.1 ≤ Ri ≤ 10) and also natural convection regime (10 < Ri ≤ 100) with fixed values of remaining parameters. A detailed parametric discussion is presented for the physical properties of flow and temperature distributions in terms of streamlines, isotherms, average heat transfer rate within the flow domain. The results show that the flow and temperature fields affected by varying of pertinent parameters. Moreover, heat transfer rate is increased by 139.50% with the increase in Richardson number from 0.1 to 100. The increasing rate of heat transfer due to Ri is respectively decreased by 58.11% with varying of Ha from 0 to 60 and increased by 23.97% with the addition of nanoparticles up to 3%. Comparison is performed against the previously published results on the basis of special cases and found to be in excellent agreement.

Magnetohydrodynamic Stagnation Point Flow with a Convective Surface Boundary Condition

2011 ◽  
Vol 66 (8-9) ◽  
pp. 495-499 ◽  
Author(s):  
Khamisah Jafar ◽  
Anuar Ishak ◽  
Roslinda Nazar
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Stagnation Point ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stagnation Point Flow ◽  
Bottom Surface ◽  
Stream Velocity ◽  
Surface Boundary ◽  
Convective Parameter

Abstract This study analyzes the steady laminar two-dimensional stagnation point flow and heat transfer of an incompressible viscous fluid impinging normal to a horizontal plate, with the bottom surface of the plate heated by convection from a hot fluid. A uniform magnetic field is applied in a direction normal to the flat plate, with a free stream velocity varying linearly with the distance from the stagnation point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically. The analysis includes the effects of the magnetic parameter, the Prandtl number, and the convective parameter on the heat transfer rate at the surface. Results showed that the heat transfer rate at the surface increases with increasing values of these quantities.

MIXED CONVECTIVE SLIP FLOWS IN A VERTICAL PARALLEL PLATE MICROCHANNEL WITH SYMMETRIC AND ASYMMETRIC WALL HEAT FLUXES

2012 ◽  
Vol 36 (3) ◽  
pp. 207-218 ◽  
Author(s):  
Hamid Niazmand ◽  
Behnam Rahimi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Friction Coefficient ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Parallel Plate ◽  
Flux Ratio ◽  
Heat Fluxes ◽  
Temperature Fields ◽  
Slip Flows

Mixed convective gaseous slip flows in an open-ended vertical parallel-plate channel with symmetric and asymmetric wall heat fluxes are numerically investigated. Buoyancy effects on developing and fully developed solutions are studied using the SIMPLE algorithm. The velocity and temperature fields are examined for different values of Knudsen number, mixed convection parameter and heat flux ratio. It is found that increasing Gr/Re leads to an increase in the heat transfer rate and friction coefficient. Also, rarefaction effects decrease the heat transfer rate and friction coefficient. The friction coefficient decreases with an increase in heat flux ratio.

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