Abstract: A method and apparatus is provided to measure in fluids including suspensions and heterogeneous mixtures time-resolved histories of velocity magnitude and vector of unidirectional, unsteady and oscillating flows. A boundary layer develops from a sharp, leading edge of a plate approached by fluid flow. Its skin friction, measured at a fixed location on the plate by a hot-film sensor connected to a constant-temperature anemometer, is uniquely related to the magnitude of the approach velocity. Temperature-sensing gauges within the range of the thermal wake from the skin friction sensor allow to determine direction of the flow.

Abstract: A method is provided to generate over a confined space precisely defined distributions of the magnitude of the wall shearing stresses in a substrate/fluid boundary layer. A fluid flow is rotated around a center axis in the confined space. Simultaneously a defined fluid volume is removed in the rotational axis of the flow per unit time and recirculated or replenished through return openings in the lid or sidewall.

Abstract: A method and apparatus is provided to generate over a confined space precisely defined distributions of the magnitude of the wall shearing stresses in a substrate/fluid boundary layer. A fluid flow is rotated around a center axis in the confined space. Simultaneously a defined fluid volume is removed in the rotational axis of the flow per unit time and recirculated or replenished through return openings in the lid or sidewall.