Pulsed wire velocity anemometry near walls

A new pulsed wire probe for making velocity and turbulence measurements in the near wall region of incompressible, isothermal boundary layers of all kinds is described. Results of careful calibrations of the probe response in both laminar and turbulent flows are presented, with particular emphasis on the effects of diffusion in the very near wall region. Analytic results for the motion and distortion of a heat puff in linear shear flow near a wall are developed and these are shown to validate a very simple approximate theory that accounts for the diffusional effects. It is demonstrated that correction procedures based on the theory can be successfully implemented. Examples of the use of the probe in highly turbulent, separated flows, as well as more standard boundary layers, are given and its response near the wall is contrasted with that of the corresponding (parallel wire) probe used for surface shear stress measurements.