The Differential Speckle Strophometry — A Light Scattering Technique for the Measurement of Velocity Gradients in Turbulent Fluid Flow

A laser light scattering technique is described which allows the measurement of velocity gradients and their temporal correlation functions in fluid flow. This non-invasive and gauge-free technique was applied to a turbulent channel flow. Results of the measurements, including the turbulent energy dissipation and the enstrophy are presented.