Simultaneous measurements of fluctuating velocity and pressure in a turbulent mixing layer

A novel experimental technique to measure static pressure fluctuation was applied in order to evaluate velocity-pressure correlation in a turbulent mixing layer. The developing region of the mixing layer was found to be out of equilibrium state, indicating the oscillatory velocity fluctuation due to vortex shedding and remarkable production of turbulence. The contribution of pressure-related terms in the transport equation of the Reynolds stress is found to be well captured by the present method. A simple model for pressure diffusion by Lumley gave a satisfactory approximation when the flow approached the self-similar state. However, the analogy between pressure diffusion and turbulent diffusion becomes weaker when the flow exhibits characteristics which are not found in the equilibrium state.