Flow distortion investigation of wind velocity perturbations for two ocean meteorological platforms

Abstract

A computational fluid dynamics (CFD) study was performed of the wind flow around two ocean buoys used to collect meteorological data from sensors mounted on the buoy tower. The CFD approach allowed wind velocity perturbations to be evaluated as a step towards quantifying the impacts of flow distortion on buoy wind measurements. The two buoys evaluated were the Wood Hole Oceanographic Institution WHOI Modular Ocean Buoy System and the University of New Hampshire (UNH) 2.1 m discus buoy. Engineering drawings were used to create a computational mesh for each buoy. Suitable solution methods were then developed and tested, CFD simulations were performed, and the results evaluated. Eleven CFD runs were performed, six for the WHOI buoy and five for the UNH buoy. Highlights of analysis for the WHOI buoy were that horizontal flow distortion was relatively small (<1%) for head-on flow, but that the tendency of the buoy to establish an angle of about 30 degrees relative to the flow resulted in acceleration at one anemometer location and deceleration at the other. Highlights of the analysis for the UNH buoy were that flow distortion of about 5% at the wind sensor location could be cut by about a factor of two by either raising the sensor by 2 ft or removing solar panels.