Studying the effect of wind direction on cross-ventilation turbulent flows

Natural ventilation depends upon the characteristics of the approaching flow (e.g. wind direction, turbulence) and the building’s openings (e.g. number, position, geometry). This study aims to examine the less understood turbulent aspects of the incoming flows for varying angles of the incident flow, under cross ventilation scenarios. Measurements that were taken during the period October 2014 – July 2015 at Silsoe, UK in the frame of the REFRESH project are used. One metal cube was equipped with two Gill R3 sonic anemometers, whilst the flows around the metal cube and upstream were measured by five sonic anemometers. Cross ventilation was established with openings of area 0.4 m2. Results show that for flows perpendicular, diagonal and parallel to the openings, velocity power spectra indoors appear flattened, implying an enhancement of the importance of small eddies indoors. When the flow is parallel to the openings, unsteady phenomena are dominant and pulsation flows develop. CFD (Openfoam) simulations facilitate the understanding of the flow development under different wind directions.