An Investigation of Turbulence Scales that Affect Particle Motion

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Abstract CTS-9612747 C. Rogers Tufts University The main objective is to measure statistical properties of turbulence as seen by a particle suspended in air flow, and to determine the mechanisms responsible for particle dispersion. A combined experimental-numerical approach is suggested to determine the fluid turbulence in the reference frame of a moving particle. A two-component laser Doppler velocimeter (LDV) measure the instantaneous fluid velocity, then one calculates the acceleration of an imaginary particle, and the LDV measuring volume follows that particle. The instantaneous vorticity and energy dissipation rate in the fluid. The turbulence length scales and the dispersion characteristics are estimated using digital particle image velocimetry (DPIV). The investigation will include low and moderate Reynolds number flows, in forced and unforced turbulence situations, with relevance for two- and three-dimensional flows. This a collaborative project between Prof. C, Rogers of Tufts University and Prof. J. Eaton and one of his students at Stanford University who will collaborate particularly in the direct numerical simulation of particle-laden flows. Several sets of experiments will be performed concerning preferential particle concentration near-isotropic turbulence, particle concentration and directed particle motion in a separated shear layer. Improved fundamental understanding of fluid turbulence-particle interaction is expected.