Accurate numerical simulation of air flows in ventilated multi-rooms

A numerical study of turbulent air flow in ventilated multi-room configurations, where both of buoyancy- and radiation-effects are of importance, is described in this paper. Our computer code solves, in finite difference form, the transient-state conservation equations for mass, momentum and thermal energy. The two equation k-e model with buoyancy terms (Boussinesq approximation) is employed for modelling of turbulence. In addition, a two-band model based on Gebhart's method has been implemented enabling the study of the effects of long wave radiation and solar radiation through windows. Our purpose here is to present a fast multigrid solver with local grid refinements. The much faster convergence rate of that solver compared with more standard single grid schemes (such as SIMPLE) allows the usage of a large number of computational elements. This together with a rational distribution of the node points is expected to achieve an improved spatial resolution and numerically accurate prediction. The model equations and the numerical methods are briefly presented. The effect of wall insulation and radiation on indoor flow and temperature fields is studied. The natural convection in partially divided rectangular enclosures is siimulated. A local grid refinement near the supply outlet and the exhaust inlet in a 3D forced convection room is demonstrated. A good agreement is shown between the predicted results and the previously reported experimental data.