1.4 Governing equations.- The

fluid flow and heat transfer is as­sumed to be governed by the two dimensional Navier-Stokes equations, together with the en­ergy equation, using the following restrictions: steady state, lam­inar flow, fluid Newtonian be­haviour, Boussinesq approxima­tions, radiatively non — partic­ipating medium and negligible both heat friction and influence of pressure on temperature. This set of differential equations are represented in Eqs. 2 — 5, where ( ) are the Cartesian — coor­

dinates; T is the temperature;

T0 the reference temperature; pd the dynamic pressure; (u, v) and ( ) are and у components

of velocity and the gravitational acceleration.

The solid parts (glass sheets) are governed by the energy equation (Eq. 5) without consid­ering convective terms.

^ + £ = 0(2) dy

■т0)дх (3)

-T0)gv (4)

Q-2JS

The governing equations can be adimensionalized using the dimensional quantities Lref = , , , and, where is the thermal

diffusivity. The following adimensional variables are obtained: , ua = ufuref,

and. The flow structure is fully described by Rayleigh and

Prandtl numbers (Ra, Pr); by the shape of the geometry (A, A’, lh/L, lc/L and S/L); and by the thermal conductivity ratio ДА.

results demonstrate that velocities Table 2: Parameters of the mesh for study III: asym — and temperatures have a periodic metrical configurations when slats are close to hot (lh/L behaviour in direction, i. e.: = 0.2 lc/L = 0.4, and ) and cold (lh/L = 0.4, lc/L

= 0.2, and ) isothermal walls.

(6)

The dynamic pressure is characterized by:

PdJ, У) = Ра{х, y + H’)+ К„ (7)

where Жр is a constant value. The Kp value is calculated from analysis of the effects of buoyancy (Kelkar [2]). In this work, it is assumed that Kp is represented by:

(8)

where T0 is the Boussinesq temperature and the bulk temperature, which were expressed by: