Estudo da convecção em cavidade quadrada com o topo deslizante preenchida com bloco sólido condutor de calor

Abstract

Convection in porous media is ubiquitous in a series of engineering applications in petroleum and chemistry industry. In this work, forced and natural convection inside a lid-driven porous square cavity is numerically simulated. The heterogeneous approach is applied to the porous media. The solid constituent of the porous media is idealized as a square solid and heat-conducting block centered inside the enclosure. Non equilibrium conditions are imposed maintaining the bottom of the cavity with a temperature lower than the top surface. Additionally, the top surface slides at constant speed supplying momentum to the fluid. The main goal is to investigate the influence of Grashof number, Reynolds number, blockage size and solid-to-fluid thermal conductivity ratio on heat transfer and fluid flow. The flow parameters range simulated covers only laminar regime, 100≤Re≤1000 and 103≤Gr≤107. Furthermore, it is simulated four cavities configurations and five values for the thermal conductivity in the range 0,1≤K≤10,0.Conservation equations are solved separately for the fluid and for the solid block through the finite volume method. The QUICK interpolation scheme is set for numerical treatment of the advection terms in the conservation of momentum and energy equations. The SIMPLE algorithm is applied for pressure-velocity coupling. The results are exposed through the Nusselt number, the stream function lines and the isotherms. In this work, forced convection and natural convection compete for heat transfer predominance inside the cavity. On one hand, increasing the Re, or decreasing Gr, leads to an increase in circulations and heat transfer enhancement. On the other hand, increasing Gr, or decreasing Re, leads to fluid stagnation and, therefore, the instauration of conduction heat transfer. The introduction of a solid block might benefit heat transfer up to a limiting blockage size since there is no stagnant fluid. If there is stagnant fluid, the block introduction might decrease heat transfer. The influence of solid-to-fluid thermal conductivity ratio relies on the cavity configuration as well as if there is stagnant fluid. If there is stagnant fluid, increasing the thermal conductivity ration yield in heat transfer enhancement. However, if there is no stagnant fluid inside the cavity, the increase in K might mitigate heat transfer