A surface source singularity model for time averaged flow around cylindrical structures

Abstract

A simple method of solution to the problem of two-dimensional separated flow around multiple-body circular cylindrical structures is presented. The method is applied to the case of two identical cylinders where the free-stream direction is perpendicular to the line joining the centers. The effect of the bodies and their wakes on the outer potential flow is modelled by surface source distributions over the front wetted surfaces. The flow in the wakes, generated by the source distributions, is ignored. The condition of the zero normal velocity is applied over the front surface to obtain an integral equation for the source strength. This equation is solved with the condition of finite velocities at the separation points to find the unknown source strength distribution and the positions of the separation points. The pressure distribution on the front wetted surface is then calculated through Bernoulli's equation. The pressure distribution on the rear surface exposed to the wake is assumed to be determined by the separation values. The effects of the distance between the bodies on the flow pattern, position of the separation points, wake under-pressure and the resultant forces are analysed. The most significant feature of the present flow model is that no empirical parameters are needed for the analysis. The empirical parameters used in other models, the back pressure coefficient and the positions of the separation points, can be predicted through the present model.