Flow distortion calculations and their application in HEXMAX

Abstract

Several methods are examined for correction of turbulence and eddy fluxes in the atmospheric boundary layer, two of them based on a potential-flow approach initiated by Wyngaard. If the distorting object is cylindrical or if the distance to the sensor is much greater than the size of the body, the undisturbed wind stress can be calculated solely from measurements made by the sensor itself; no auxiliary measurements or lengthy model calculations are needed. A more general potential-flow correction has been developed in which distorting objects of complex shape are represented as a number of ellipsoidal elements. These models are applied to data from three turbulence anemometers with different amounts of flow distortion. The results were used to correct mean winds, but simulation of distortion effects on turbulence levels and wind stress turned out not to be feasible. -from Authors