Unsteady Mixed Convection of a Confined Jet in a Fluid-Superposed High Porosity Medium

Numerical study of a confined jet impingement cooling of a fluid-superposed porous medium heated from below is conducted to investigate the oscillatory mixed convection. The effects of the Rayleigh number (2x105Ra1x106) and the Darcy number (1x10-5Da5x10-4) on the heat transfer are investigated for different Peclet numbers. It is found that, the average Nusselt number increases with the increase in Darcy number or Rayleigh number. The values of average Nusselt number are found to oscillate with time for some combination of Rayleigh numbers (Ra epsilon 4x105) and Peclet numbers (200Pe1000), at which the oscillatory convection occurs. The oscillation of average Nusselt number is investigated for different porous medium height and porous medium-to-fluid heat capacity ratio.