Horizontal buoyancy effects on the pressure distribution of a body in a duct

Abstract

It is well known that the static pressure coefficient values obtained from tests of axisymmetric bodies in, for example, a large water tunnel indicate the existence of tunnel wall interference. This interference is due to blockage experienced by the body operating within the boundaries of the test section walls, and to the skin friction on both the tunnel walls and the surface of the body which, in turn, causes finite thickness boundary layers to develop. These factors result in a decrease in static pressure along the test section which leads to a spurious horizontal buoyancy on the body. Potential flow calculations can only account for solid blockage effects. A control volume analysis has thus been carried out from which pressure coefficient correction terms due to horizontal buoyance have been obtained. The present method permits one to treat relatively large bodies which have a much stronger interaction with the tunnel walls. These correction factors are computed for a large, streamlined body operating over a range of velocities.