Airflow over the RRS Discovery: the variation of velocity errors with relative wind direction for anemometers mounted on cruise D223 and D224

The Computational Fluid Dynamics (CFD) model VECTIS was used to model the effect of airflow distortion, caused by the hull and superstructure of the ship, on wind speed measurements made during two cruises of the R.R.S. Discovery. Wind speed errors are calculated for the positions of the anemometers on cruises D223 and D224. The cruises were instrumented with a total of 9 anemometers for the purpose of evaluating the CFD model. The VECTIS models considered in this report simulate a boundary layer wind speed profile with a 10 m wind speed of 13.8 ms-1. Wind speed errors were calculated for flows directly over the bow, and for flows at angles of ±15° and ±30° off the bow. This report shows that the errors varied with relative wind direction. The anemometers located on the foremast platform experienced flows which had been both accelerated by up to 5 % and displaced vertically by up to 2m. Anemometers placed above the bridge experienced flows which had been decelerated by up to 15% and displaced vertically by up to 6m.