Mixed Convection in Non-Newtonian Fluids Along a Horizontal Plate in a Porous Medium

1997 ◽  
Vol 119 (1) ◽  
pp. 34-37 ◽  
Author(s):  
M. Kumari ◽  
Rama Subba Retty Gorla ◽  
L. Byrd
Keyword(s):  
Heat Flux ◽  
Porous Medium ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Power Law ◽  
Viscosity Index ◽  
Temperature Fields ◽  
Horizontal Plate ◽  
Velocity And Temperature Fields ◽  
Variable Wall

The problem of mixed convection from horizontal surfaces in a porous medium saturated with a power-law-type non-Newtonian fluid is investigated. The transformed conservation laws are solved numerically for the case of variable wall heat flux conditions. Results for the details of the velocity and temperature fields as well as the Nusselt number have been presented. The viscosity index ranged from 0.5–1.5.

Mixed Convection Adjacent to 3-D Backward-Facing Step

2000 ◽  
Author(s):  
A. Li ◽  
B. F. Armaly
Keyword(s):  
Heat Flux ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Buoyancy Force ◽  
Three Dimensional ◽  
The Other ◽  
Convection Flow ◽  
Backward Facing Step ◽  
Grashof Number ◽  
Recirculating Flow

Abstract Results from three-dimensional numerical simulation of laminar, buoyancy assisting, mixed convection airflow adjacent to a backward-facing step in a vertical rectangular duct are presented. The Reynolds number, and duct geometry were kept constant at Re = 200, AR = 8, ER = 2, and S = 1 cm. Heat flux at the wall downstream from the step was kept uniform, but its magnitude was varied to cover a Grashof number (Gr) range between 0.0 to 4000. All the other walls in the duct were kept at adiabatic condition. The flow, upstream of the step, is treated as fully developed and isothermal. The relatively small aspect ratio of the channel is selected specifically to focus on the developments of the three-dimensional mixed convection flow in the separated and reattached flow regions downstream from the step. The presented results focus on the effects of increasing the buoyancy force, by increasing the uniform wall heat flux, on the three-dimensional flow and heat transfer characteristics. The flow and thermal fields are symmetric about the duct’s centerline. Vortex generated near the sidewall, is the major contributor to the three dimensional behavior in the flow domain, and that feature increases as the Grashof number increases. Increasing the Grashof number results in an increase in the Nusselt number, the size of the secondary recirculating flow region, the size of the sidewall vortex, and the spanwise flow from the sidewall toward the center of the channel. On the other hand, the size of the primary reattachment region decreases with increasing the Grashof number. That region lifts away and partially detaches from the downstream wall at high Grashof number flow. The maximum Nusselt number occurs near the sidewalls and not at the center of the channel. The effects of the buoyancy force on the distributions of the three-velocity components, temperature, reattachment region, friction coefficient, and Nusselt number are presented, and compared with 2-D results.

Augmentation of Pure Mixed Convection Heat Transfer in a Non-newtonian Power-law Fluid Filled Lid-driven Trapezoidal Cavity with Double Rotating Cylinders

2021 ◽  
Author(s):  
Hasib Ahmed Prince ◽  
Didarul Ahasan Redwan ◽  
Enamul Hasan Rozin ◽  
Sudipta Saha ◽  
Mohammad Arif Hasan Mamun
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Numerical Investigation ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Cavity Surface ◽  
Rotating Cylinders ◽  
Power Law Fluid ◽  
Driven Cavity

Abstract In this study, a numerical investigation on mixed convection inside a trapezoidal cavity with a pair of rotating cylinders has been conducted. Three different power-law fluid indexes (n = 1.4, 1.0, and 0.6) have been considered to model different sets of non-Newtonian fluids. Four separate cases are considered dependent on the rotation orientation of the cylinders within the cavity. In the first two cases, the cylinders rotate in the same direction, i.e., both counter-clockwise (CCW), and both clockwise (CW), whereas, in the other two cases, cylinders rotate in opposite directions (CW-CCW and CCW-CW). Simulations have been carried out over a broad range of Reynolds number (from 0.5 to 500) and angular speeds (a dimensionless value from 0 to 10). The average Nusselt number values at the isothermal hot inclined cavity surface are determined to evaluate heat transfer performance in various circumstances. Streamlines and isotherm contours are also plotted for better understandings of the effects of different cases for various parameters on thermal and fluid flow fields. It is found that the Nusselt number varies non-linearly with different angular speeds of the cylinders. The combined effect of the mixing induced by cylinder rotation and viscosity characteristics of the fluid dictates the heat transfer in the system. Predictions from the numerical investigation provide insights onto the sets of key parametric configuration that have dominant influence on the thermal performance of lid driven cavity with double rotating cylinders.

scholarly journals Numerical Study of Mixed Convection in a Channel Filled with a Porous Medium

2019 ◽  
Vol 9 (2) ◽  
pp. 211 ◽  
Author(s):  
Filiz Ozgen ◽  
Yasin Varol
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Mixed Convection ◽  
Nuclear Waste ◽  
Numerical Study ◽  
Temperature Fields ◽  
Dimensionless Form ◽  
Geothermal Resources ◽  
Nusselt Numbers ◽  
The Finite Difference Method

The heat transfer of mixed convection in a horizontal channel filled with a porous medium has been studied in this article, given that it plays an extensive role in various technical applications, such as flow of fluid in geothermal resources, formations in chemical industries, the storage of radioactive nuclear waste material, and cooling. Those equations written in a dimensionless form have been solved using the finite difference method for different values of the parameters. The results obtained from the study have been presented through streamlines, isotherms, and both local and average Nusselt numbers. It has been observed that parameters such as the Rayleigh and Peclet numbers have an effect on flow and temperature fields.

Unsteady Natural Convection in the Vicinity of a Doubly Infinite Vertical Plate

1962 ◽  
Vol 84 (4) ◽  
pp. 334-338 ◽  
Author(s):  
J. A. Schetz ◽  
R. Eichhorn
Keyword(s):  
Heat Flux ◽  
Natural Convection ◽  
Surface Heat Flux ◽  
Vertical Plate ◽  
Surface Heat ◽  
Temperature Fields ◽  
Flow Equations ◽  
Velocity And Temperature Fields ◽  
Unsteady Natural Convection ◽  
Infinite Vertical Plate

The viscous flow equations for the unsteady free convection of a fluid near a doubly infinite vertical plate whose temperature or heat flux is an arbitrary function of time are treated by means of Laplace transforms. Exact solutions are obtained for several typical examples with arbitrary Prandtl number. The results are then generalized to give integral expressions for the velocity and temperature fields due to any prescribed time variation in wall temperature or surface heat flux.

Natural Convection of Non-Newtonian Fluids About a Horizontal Surface in a Porous Medium

1987 ◽  
Vol 109 (3) ◽  
pp. 119-123 ◽  
Author(s):  
H. T. Chen ◽  
C. K. Chen
Keyword(s):  
Heat Flux ◽  
Porous Medium ◽  
Natural Convection ◽  
Power Law ◽  
Flux Distribution ◽  
Similarity Solutions ◽  
Iteration Scheme ◽  
Heat Flux Distribution ◽  
Runge Kutta Method ◽  
Power Law Index

The problem of natural convection of a non-Newtonian power-law fluid about a horizontal impermeable surface in the porous medium is considered, where the plate is assumed with a nonuniform heat flux distribution. The present study is based on the boundary layer approximation and only suitable for a high Rayleigh number. Similarity solutions are obtained by using the fourth-order Runge-Kutta method and the Nachtsheim-Swigert iteration scheme. The effects of the nonuniform wall heat flux qw(x) and the new power-law index n on the heat transfer characteristics are discussed.

Chemically Reacting MHD Mixed Convection Variable Viscosity Blasius Flow Embedded in a Porous Medium

2017 ◽  
Vol 374 ◽  
pp. 83-91 ◽  
Author(s):  
Oluwole Daniel Makinde ◽  
S.R. Mishra
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Skin Friction ◽  
Sherwood Number ◽  
Variable Viscosity ◽  
Fluid Viscosity ◽  
Reaction Heat ◽  
Blasius Flow

In this paper, the combined effects of magnetic field, buoyancy forces, nth order chemical reaction, heat source, viscous dissipation, Joule heating and variable viscosity on mixed convection Blasius flow of a conducting fluid over a convectively heated permeable plate embedded in a porous medium is investigated. The fluid properties are assumed to be constant except for the density variation with the temperature and reacting chemical species concentration. The nonlinear governing differential equations were obtained and solved numerically using the Runge-Kutta-Fehlberg method with shooting technique. The dimensionless velocity, temperature and concentration profiles are shown graphically. The effects of pertinent parameters on the skin friction, Nusselt number and Sherwood number are examined. It is found that skin friction decreases while Nusselt number and Sherwood number increase with a decrease in the fluid viscosity in the presence of magnetic field.

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