scholarly journals Non-Newtonian fluid flow in annular pipes and entropy generation: Temperature-dependent viscosity

Sadhana ◽  
2006 ◽  
Vol 31 (6) ◽  
pp. 683-695 ◽  
Author(s):  
M. Yürüsoy ◽  
B. S. YilbaŞ ◽  
M. Pakdemirli
Author(s):  
Harshad Sanjay Gaikwad ◽  
Pranab Kumar Mondal ◽  
Dipankar Narayan Basu ◽  
Nares Chimres ◽  
Somchai Wongwises

In this article, we perform an entropy generation analysis for the micro channel heat sink applications where the flow of fluid is actuated by combined influences of applied pressure gradient and electric field under electrical double layer phenomenon. The upper and lower walls of the channels are kept at different constant temperatures. The temperature-dependent viscosity of the fluid is considered and hence the momentum equation and energy equations are coupled in this study. Also, a hydrodynamic slip condition is employed on the viscous dissipation. For complete analysis of the entropy generation, we use a perturbation approach with lubrication approximation. In this study, we discuss the results depicting variations in the velocity and temperature distributions and their effect on local entropy generation rate and Bejan number in the system. It can be summarized from this analysis that the enhanced velocity gradients in the flow field due to combined effect of temperature-dependent viscosity and Joule heating and viscous dissipative effects, leads to an enhancement in the local entropy generation rate in the system.


2020 ◽  
Vol 10 (2) ◽  
pp. 708 ◽  
Author(s):  
Hafiz Abdul Wahab ◽  
Hussan Zeb ◽  
Saira Bhatti ◽  
Muhammad Gulistan ◽  
Seifedine Kadry ◽  
...  

The main aim of the current study is to determine the effects of the temperature dependent viscosity and thermal conductivity on magnetohydrodynamics (MHD) flow of a non-Newtonian fluid over a nonlinear stretching sheet. The viscosity of the fluid depends on stratifications. Moreover, Powell–Eyring fluid is electrically conducted subject to a non-uniform applied magnetic field. Assume a small magnetic reynolds number and boundary layer approximation are applied in the mathematical formulation. Zero nano-particles mass flux condition to the sheet is considered. The governing model is transformed into the system of nonlinear Ordinary Differential Equation (ODE) system by using suitable transformations so-called similarity transformation. In order to calculate the solution of the problem, we use the higher order convergence method, so-called shooting method followed by Runge-Kutta Fehlberg (RK45) method. The impacts of different physical parameters on velocity, temperature and concentration profiles are analyzed and discussed. The parameters of engineering interest, i.e., skin fraction, Nusselt and Sherwood numbers are studied numerically as well. We concluded that the velocity profile decreases by increasing the values of S t , H and M. Also, we have analyzed the variation of temperature and concentration profiles for different physical parameters.


2021 ◽  
Author(s):  
Zakir Hussain ◽  
Tasawar Hayat ◽  
Ahmed Alsaedi

Abstract The addressed work explains SWCNT (Single walled carbon nanotubnes) and MWCNT (Multi walled carbon nanotubnes) nanofluid flow under the influences of temperature dependent viscosity and mixed convection. Comparative study of SWCN-T and MWCNT suspended in base liquid is presented. Further heat and mass transfer are addressed for nanofluid effected by radiation, heat generation/absorption and diffusion species. Mathematical development of problem is taken in cylindrical coordinates. System of highly nonlinear differential equations are constructed via appropriate transformations. The system of equations are tackled numerically by bvp4c MATLAB solver. The findings of the study show that volume fraction contributes to decline the fluid flow by cylindrical shaped nanoparticles. In addition, fluid flow decelerates via curvature and magnetic parameters while it boots by Grashof number and volume fraction. Further more, temperature dependent viscosity variable corresponds to decrease the temperature close to the surface and it develops away from the surface. The temperature advances in MWCNT-liquid than SWCNT-liquid. Volume fraction and magnetic parameters correspond to skin friction coefficient enhancement. Heat transfer rate increases for larger curvature and heat generation parameters and reverse trend holds against radiation parameter.


2021 ◽  
Vol 408 ◽  
pp. 33-49
Author(s):  
Lazarus Rundora

This article analyses the thermal decomposition in an unsteady MHD mixed convection flow of a reactive, electrically conducting Casson fluid within a vertical channel filled with a saturated porous medium and the influence of the temperature dependent properties on the flow. The fluid is assumed to be incompressible with the viscosity coefficient varying exponentially with temperature. The flow is subjected to an externally applied uniform magnetic field. The exothermic chemical kinetics inherent in the flow system give rise to heat dissipation. A technique based on a semi-discretization finite difference scheme and the shooting method is applied to solve the dimensionless governing equations. The effects of the temperature dependent viscosity, the magnetic field and other important parameters on the velocity and temperature profiles, the wall shear stress and the wall heat transfer rate are presented graphically and discussed quantitatively and qualitatively. The fluid flow model revealed flow characteristics that have profound ramifications including the increased heat transfer enhancement attributes of the reactive temperature dependent viscosity Casson fluid flow.


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