Non-Boussinesq approach for turbulent buoyant flows in enclosure with horizontal vent and forced inlet port

• Non-Boussinesq variable density approach is used to investigate turbulent buoyant flows.
• Compressible form of UFANS equation is solved using high accuracy compact schemes.
• Average Nusselt number and net mass flow rate vary significantly with rise in inlet port size and velocity.
• Boussinesq approximation over-predicts the heat transfer rate.
• Inlet port location suppresses buoyancy and affects the plume structures.

The effects of forced ambient velocity on thermal plume behavior in a ceiling vented square enclosure are numerically investigated. Turbulence is modeled by unsteady Favre-averaged Navier–Stokes (UFANS) equation with Lam Bremhorst low Reynolds number k−ɛk−ɛ turbulence model. A non-Boussinesq variable density approach is used to model the density variations. Simplified Marker and Cell (SMAC) algorithm is used to solve the governing equations on collocated grid with high accuracy compact finite difference schemes. The pressure Poisson equation is solved by bi-conjugate gradient algorithm and time integration is performed with four stage Runge–Kutta method (Rk-4). The results are presented for Grashof number Gr = 1011 and 1012 and Gay-Lussac number Ga = 0.2 and 2. The present model is valid when buoyancy effects are significant in comparison with forced convection effects. The heat transfer characteristics are analyzed by varying forced inlet velocity, inlet port size and inlet port location. The assisting flow enhances plume discharge rate and increases convective heat loss from cavity. The opposing flow weakens thermal buoyancy and minimizes convective heat loss from cavity. The present mathematical model and numerical method are in good agreement with the existing results available in the literature.