The effect of aspect ratio on the laminar free convection inside a vertical channel heated isothermally

In this work, different aspect ratios for channel composed of two parallel vertical isothermal plates is heated symmetrically, where a laminar free convection heat transfer is investigated numerically, to predict the behavior of the flow inside the channel. The boundary, initial conditions and the effects at the inlet and exit of the channel were concluded in the study. The numerical solution is conducted for Pr = 0.7, and different values of Rayleigh number, Ra = 10 ÷ 10
⁵
, with constant walls temperature, and at very large range of aspect ratios AR = 1 200. Fully Navier-Stokes and energy equations were solved by using the finite volume technique. The values of local Nusselt number are identical for the flow nearby the two vertical walls, also mean Nusselt number varies from high values at the channel entrance at the bellow to small values nearby the channel exit, where the mean air temperature inside the channel tends to be constant due to heat transfer between the air flow and channel walls. Reynolds number values increase with the increase of values of Rayleigh number, due to buoyancy effects. It is established, that with increase of a parameter AR heat transfer is reduced, but Reynolds' number between the plates, on the contrary, grows.