Use of electrochemical techniques to study turbulence close to a wall

Electrochemical techniques can be used to measure the time averaged velocity gradient and the two components of the fluctuating velocity gradient at a solid surface. A chemical reaction is carried out at the surface of a small electrode embedded in the wall. The voltage applied to the electrode is large enough that the current flowing in the circuit is controlled by the mass transfer rate. A typical flow system in which the techniques have been used is discussed.