Flow structures stability analysis in a model of a cattle barn using oscillating pattern decomposition method

Abstract

A model of a cattle barn and a part-depth atmospheric boundary layer were scaled down to 1:50 to simulate the natural ventilation in a wind tunnel. We studied the impact of three opening configurations (entirely, half and quarterly open, which represented 0.7, 0.35 and 0.17 wall porosity, respectively), on the mean flow and the stability of the flow structures in the barn using time-resolved PIV technique and oscillating pattern decomposition method (OPD). While we observed the most-energy-containing structures (POD modes) in the case of the half opening, the most stable structures (OPD modes) correspond to the fully open case. We found that the stability of the structures increases with the opening width (wall porosity), and the highest frequency of these structures was 11 Hz.