Numerical Simulation of Mixed Convection Airflow Under a Dome-Shaped Roof

Mixed convection airflow under a ventilated dome-shaped roof is studied numerically using the Low-Reynolds-Number (LRN) k−ω model for turbulence modeling. The axisymmetric two-dimensional governing equations are discretized using control volume approach. The SIMPLER algorithm is used for coupling between pressure and velocity components. Air is used as the working fluid and computational results are presented in the form of streamline and temperature patterns. The local and average Nusselt numbers over the heated and cooled boundaries for a wide range of Reynolds numbers (Re = 1 × 102−5 × 104) and Grashof numbers (Gr = 1 × 103−1 × 1010) which include both laminar and turbulent flow regimes are presented as well. The results are categorized into two primary flow patterns based on the inflow Reynolds number values. The influence of Reynolds number, Grashof number, and inflow non-dimensional temperature on the flow filed and thermal patterns is shown and discussed. The results show that in the natural convection dominated regime, by increasing Grashof number most of the air motion is restricted beneath the hot dome. Meanwhile, much of the core region is occupied with a low velocity fluid which are the characteristics of a stable thermal stratification. In the forced convection dominated flow regime, two primary patterns were recognized. In the first pattern a simple flow is formed, while in the second pattern a strong clockwise shear vortex under the dome hot surface is created. Thermal communication between the hot and cold surfaces is attributed to the presence of this shear vortex.

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