Study on convective heat transfer from pig models by CFD in a virtual wind tunnel

Abstract

Heat stress strongly affects the pig production in hot climate regions, including the summer of many continental climate regions. Although it is recognized that increasing the local air speed in the animal occupied zone is one of the effective approaches to decrease the heat stress of pigs, few studies have been found to quantify the relationship of air speed and convective heat transfer from the pigs. The main objective of this study is to evaluate the impact of airflow speed, turbulence intensity, and animal orientation on the convective heat transfer so that it can be implemented into ventilation control algorithms to provide a better production environment. The study was mainly performed by CFD simulations in two geometry models, a pig model with actual size and a simplified cylinder model, in virtual wind tunnel. The validation of CFD modelling was conducted by comparing the simulated Nusselt number with the values determined by semi-experimental equation for cylinder geometry model. The effects of air speed, inlet turbulence intensity, air incidence angles and pig skin modelling on convective heat transfer coefficients were studied. It is proved that CFD method could be a very good alternative way for this kind of study. The convection heat transfer of a pig model has similar tendency with the cylindrical model following the increasing of air speed. A correlation of convective heat transfer coefficient was found between the geometry of actual pig model and cylinder model. The orientation and turbulence intensity significantly affect the convective heat transfer coefficient of pig, and the results indicate animal orientation and turbulence intensity need to be considered for model development process of the convective heat transfer of pig.