Numerical Computation of Two-Dimensional Flow Around and Through a Peaked-Roof Building

Abstract

ABSTRACT Anumerical model was developed to investigate flow around and through a two-dimensional peaked-roof building dimensionally similar to a typical poultry building. Differential equations for vorticity and stream function were solved using finite differences. Converged solutions were obtained with solid building walls and a laminar upstream velocity profile at Reynolds numbers (Re)* of 10, 50, and 75, and with equal 25, 50, and 75% wall openings on windward and leeward walls at Re = 10 and 50. An algebraic model was developed to predict ventilation rates for laminar and turbulent flow to compensate for the low Re limitation of the numerical model. Algebraic and numerical model predictions were compared to flow in a wind tunnel study using a physical model of the same shape and Re of 20,000 (Bottcher et al., 1986), and to wind ventilation rates calculated according to ASHRAE (1981). Dimensionless ventilation rates from the numerical model were lower than those measured in the wind tunnel study. Ventilation rates calculated using the algebraic model for laminar flow were comparable to numerical model results. Ventilation rates calculated using the algebraic model for turbulent flow with the wind tunnel and power-law velocity profiles were comparable to wind tunnel measurements and to recommendations from ASHRAE (1981), respectively.