Three-dimensional airflow in a livestock test room with two-dimensional boundary conditions

This work is part of a project to develop numerical simulation methods for predicting the effect of animals and pen partitions on the airflow in the animal-occupied zone. As a reference case for this, it was desired to create a steady two-dimensional flow near the floor in an empty test room(8.5 m long, 3 m high and 5 m wide). A plane walljet is usually expected to generate a two-dimensional airflow and therefore the test room was equipped with a slot inlet beneath the ceiling on one entire wall of the room. A slot outlet was placed in the floor near the inlet wall. Numerical simulation and measurements of air velocity and airflow direction revealed that the flow was highly three-dimensional. The three-dimensional effects were analysed in a number of additional numerical simulations and it was found that the relation between room width and room height had a crucial influence on the development of the three-dimensional effects of the airflow. The three-dimensional effects were small unless the room width to height ratio was larger than one, and in rooms with width to height ratios larger than about three, simulations showed a number of similar airflow patterns repeated transversely to the main flow direction. (C) 1999 Silsoe Research Institute.