Probability distribution of forces and pressures on a square cylinder

Abstract

Wind tunnel experiments on a three-dimensional square cylinder model revealed that, except perhaps on the frontal face, the probability distribution of pressures, forces or overturning moments are not normal (gaussian). In fact, on points where the effect of the Karman vortices is pronounced the probability distribution of pressures shows a significant skewness to the left and kurtosis (peakdeness). This means that the negative pressure peaks are more intense than the positive pressure peaks and the crest factor is considerably larger than 3.0 or 4.0.The present paper discusses this subject and shows results regarding smooth or turbulent shear flow. Besides probability distribution curves, parameters such as mean value, rms value, crest factor, and skewness and kurtosis coefficients (for pressures on several points, for forces on individual faces, and for global forces) are also presented.