Low or High Peclet Number Flow Past a Prolate Spheroid in a Saturated Porous Medium

An experimental and numerical investigation of mixed convection phenomena about a finite-length, vertical, cylindrical heat source in a uniform, liquid-saturated, porous medium was conducted. Buoyancy-induced upflow about the heat source was systematically altered by the superposition of vertical, pressure-driven flows which opposed the buoyancy-induced fluid motion. The evolution of the mixed convection velocity and thermal fields with increasing magnitude of the imposed-flow Peclet number are reported. The ratio of the natural convection Rayleigh number Ra to the imposed-flow Peclet number Pe is shown to be the nondimensional parameter that characterizes the relative influence of buoyancy-induced to pressure-driven fluid motion. Using total disappearance of buoyancy-induced upflow as the criterion, the transition from mixed to forced convection, for opposing flows, is numerically predicted to occur for |Ra/Pe| ≈ 1/2, independent of the heat source length or power input.

Download Full-text

Influence of variable permeability on combined free and forced convection flow past a semi-infinite vertical plate in a saturated porous medium

Heat and Mass Transfer ◽

10.1007/s00231-003-0430-3 ◽

2004 ◽

Vol 40 (5) ◽

pp. 341-346 ◽

Cited By ~ 17

Author(s):

A. A. Mohammadein ◽

N. A. El-Shaer

Keyword(s):

Porous Medium ◽

Forced Convection ◽

Vertical Plate ◽

Saturated Porous Medium ◽

Convection Flow ◽

Variable Permeability ◽

Flow Past ◽

Free And Forced Convection ◽

Forced Convection Flow ◽

Infinite Vertical Plate

Download Full-text

Magnetohydrodynamics and Soret Effects on Bioconvection in a Porous Medium Saturated With a Nanofluid Containing Gyrotactic Microorganisms

Journal of Heat Transfer ◽

10.1115/1.4026039 ◽

2014 ◽

Vol 136 (5) ◽

Cited By ~ 21

Author(s):

S. Shaw ◽

P. Sibanda ◽

A. Sutradhar ◽

P. V. S. N. Murthy

Keyword(s):

Porous Medium ◽

Differential Equations ◽

Sherwood Number ◽

Peclet Number ◽

Volume Fraction ◽

Soret Effect ◽

Magnetic Field Effect ◽

Lewis Number ◽

Solute Concentration ◽

Péclet Number

We investigate the bioconvection of gyrotactic microorganism near the boundary layer region of an inclined semi infinite permeable plate embedded in a porous medium filled with a water-based nanofluid containing motile microorganisms. The model for the nanofluid incorporates Brownian motion, thermophoresis, also Soret effect and magnetic field effect are considered in the study. The governing partial differential equations for momentum, heat, solute concentration, nanoparticle volume fraction, and microorganism conservation are reduced to a set of nonlinear ordinary differential equations using similarity transformations and solved numerically. The effects of the bioconvection parameters on the thermal, solutal, nanoparticle concentration, and the density of the micro-organisms are analyzed. A comparative analysis of our results with previously reported results in the literature is given. Some interesting phenomena are observed for the local Nusselt and Sherwood number. It is shown that the Péclet number and the bioconvection Rayleigh number highly influence the local Nusselt and Sherwood numbers. For Péclet numbers less than 1, the local Nusselt and Sherwood number increase with the bioconvection Lewis number. However, both the heat and mass transfer rates decrease with bioconvection Lewis number for higher values of the Péclet number.

Download Full-text

The drag of a body moving transversely in a confined stratified fluid

Journal of Fluid Mechanics ◽

10.1017/s0022112070002458 ◽

1970 ◽

Vol 43 (2) ◽

pp. 407-418 ◽

Cited By ~ 14

Author(s):

M. R. Foster ◽

P. G. Saffman

Keyword(s):

Peclet Number ◽

Slow Motion ◽

Shear Layers ◽

Stratified Fluid ◽

Rotating Fluid ◽

Péclet Number ◽

Fluid Layers ◽

Number Problem ◽

Number Flow ◽

Large Peclet Number

The slow motion of a body through a stratified fluid bounded laterally by insulating walls is studied for both large and small Peclet number. The Taylor column and its associated boundary and shear layers are very different from the analogous problem in a rotating fluid. In particular, the large Peclet number problem is non-linear and exhibits mixing of statically unstable fluid layers, and hence the drag is order one; whereas the small Peclet number flow is everywhere stable, and the drag is of the order of the Peclet number.

Download Full-text

Solidification With a Throughflow in a Porous Medium

Journal of Heat Transfer ◽

10.1115/1.2911333 ◽

1992 ◽

Vol 114 (3) ◽

pp. 675-680

Author(s):

T. Banerjee ◽

C. Chang ◽

W. Wu ◽

U. Narusawa

Keyword(s):

Porous Medium ◽

Porous Media ◽

Analytical Solutions ◽

Peclet Number ◽

Flow In Porous Media ◽

Circular Pipe ◽

Parallel Plates ◽

Péclet Number ◽

Solid Interface

A steady throughflow in a porous medium is studied in the presence of a solidified layer due to cooling of the walls. Under the assumption of a moderately sloped melt-solid interface, analytical solutions are obtained for both a flow between parallel plates and a circular pipe. Differences and similarities are examined between the Darcian and the Brinkman porous media, as well as the effects of various parameters, such as the Peclet number, the ratio of diffusivities in the longitudinal and the lateral directions, and a parameter indicating the degree of wall cooling and flow heating, on thermofluid structure of a flow in porous media accompanied by solidification.

Download Full-text