CFD study of the influence of laying hen geometry, distribution and weight on airflow resistance

Abstract Proper indoor environment is essential to the production performance of laying hens, one effective approach to research it was Computational Fluid Dynamics (CFD). However, the modelling is a great issue as modelling individual hen would generate large number of mesh, an alternative is to simplify caged laying hen occupied zone (CZ) into porous media zone. As for it, the flow resistance of CZ requires firstly to calculate the resistance coefficients. In this study, CFD simulation was applied to calculate the resistance in three directions perpendicular to each other. The effect of the hen model geometry (full-geometry, ellipsoidal and body only model in which hen’s head, neck and legs were neglected), spatial distribution (four, three and two hens stand near the feeding through, respectively) and body weight (1.5 kg, 1.8 kg and 2.0 kg) were investigated on flow resistance. Finally, the resistance coefficients were obtained under different situations. The numerical model was firstly validated against wind tunnel experiment with five spheres representing hens. Different turbulence models were evaluated and the RNG k-e model showed the superior performance than others. Hen model geometry, the spatial distribution and body weight of hens showed significant effect on flow resistance of CZ, the resistance increased with hens’ body weight while its variation decreased. The resistance coefficients determined in this study can be directly applied to other related simulation studies using porous media to represent CZ.