In this work we present the results of a joint effort of three Leibniz Institutes (ATP, TROPOS and WIAS) leading to the validation of numerical methods and software for fluid simulations. The benchmark problem is motivated by the application in livestock husbandry, in which the understanding flow characteristics is of extreme importance in order to guarantee good quality fresh air and being environmentally sparing.In this field, CFD represents a valuable tool that enable simulation of flow patterns in different configurations. In order to assess the performance of different CFD approaches (including different solver, flow models and numerical methods) three open source models are compared: ASAM (developed at TROPOS), OpenFOAM and ParMooN (developed at WIAS). The results are compared with measurements obtained by wind tunnel experiments.