ABSTRACT
The force due to wall shear stress is a quantity of primary importance in aerodynamic problems. In engineering applications, its overall value is usually estimated from the measurement of the gross drag force. The floating element method is a direct method for measuring the wall shear stress. This method is used for measuring the skin friction directly on a flat plate. The diameter of the tube is large enough to ensure that the main part of the tube diameter is in the fully turbulent zone of the flow along the wall. The fence technique is an indirect method for measuring wall shear stress. The heat transfer gauge can be used to measure wall shear over a very small area in laminar or turbulent flows with or without pressure gradient. This instrument operates on the principle that the heat transfer from the wall to the flow is a function of wall shear stress.
