MIXED CONVECTION IN HORIZONTAL NON-DARCY POROUS MEDIUM LOCALLY HEATED FROM BELOW

摘要

A two-dimensional mixed convection flow of a viscous incompressible fluid through a fluid-saturated non-Darcy porous layer is studied numerically. The layer is assumed to be bounded by the isothermally cooled, impermeable horizontal wall on the top and an insulated, impermeable wall at the bottom. A finite isothermal flat or rectangular heat source is considered in the middle of the bottom wall. The dimensional governing equations have been solved using finite difference method for a wide range of Rayleigh number, Peclet number, non-Darcy or Forchheimer resistance parameter, and the width and height of the rectangular heat source. For increasing values of the Peclet number and the non-Darcy number, more energy is convected in the downstream region of the heat source. The upward evolution of fluid is significantly enhanced and the size of convective cells is elongated with higher values of the Rayleigh number. Also temperature plumes are observed on the top of the heat source. As the height or width of the heat source is increased the secondary convective cells clearly appear over the heat source. Moreover, the Nusselt number at the top surface of the heat source is substantially increased owing to the increase of the height and width of the heat source, whereas it diminishes with the increase of the non-Darcy parameter. In the case of wider heat source, multiple maximum and minimum values of the Nusselt number are seen.