Shklyar, A., Institute of Agricultural Engineering, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel
Arbel, A., Institute of Agricultural Engineering, Agricultural Research Organization, Volcani Center, Bet Dagan, Israel

A 3-D numerical model of the turbulent incompressible flow through screens was developed. Several turbulence models from the commercial package FLUENT for computational fluid dynamics (CFD) were tested: the standard RNG and realizable k-ε models, the standard and transient SST k-ω models, and the Reynolds stress model (RSM). Enhanced wall functions are involved in all these models. Numerical results were compared with well documented experimental results for turbulent flow through screens in wind tunnels. The decay of turbulence was predicted well by the transient SST k-ω model. Numerical modeling of the screen with a transient SST k-ω model enabled us to draw some conclusions that we used in the numerical model of the screen and in applying a simple k-ε turbulent model to examine the interactions of external, internal and screen flows. Simulation results (pressure drop across screen, tangential force, and production and dissipation rate of the turbulent kinetic energy) are incorporated into the numerical model, which is capable of modeling a screen as a virtual screen with source that exerts a drag on the flow and accordingly creates a pressure drop and changes the velocity components. Reduction of velocity components and flow turning were simulated by inputting a force into the momentum equation. The effects of turbulence generation were reproduced by fixing kinetic energy generation at the virtual screen. The numerical results yielded by simulation of the screen as a virtual screen agreed well with those of a full numerical model of the screen.