Interwake Turbulence Properties of Homogeneous Dilute Particle-Laden Flows
The properties of turbulence generated by uniform uxes of monodisperse spherical particles moving through a uniform owing gas were studied experimentally, emphasizing the properties of the region surrounding individual wake disturbances, i.e., the turbulent interwake region. Mean and uctuating values, probability density functions, and energy spectra of streamwise and cross-stream velocities were measured within a counter owing particle/air wind tunnel using particle wake discriminating laser
... criminating laser velocimetry. Test conditions included nearly monodisperse glass spheres having diameters of 0.5-2.2 mm, particle Reynolds numbers of 106-990, mean particle spacings of 13-208 mm, particle volume fractions less than 0.003%, direct rates of dissipation of turbulence by particles less than 4%, and turbulence generation rates suf cient to yield streamwise relative turbulence intensities in the range 0.2-1.5%. The turbulent interwake region was homogeneous and nearly isotropic with probability density functions that are well approximated by Gaussian functions. Relative turbulence intensities were correlated effectively based on an analogy to the properties of isotropic grid-generated turbulence by scaling with the mean particle spacing normalized by the particle wake momentum diameter. For present turbulence generation conditions the turbulent interwake region had turbulence Reynolds numbers of 0.4-3.5 and was in the nal decay period where vortical regions ll the turbulent interwake region but are sparse. This implies enhanced rates of dissipation of turbulent kinetic energy and decreasing macroscale/microscale ratios of the turbulence with increasing Reynolds numbers, as opposed to increasing ratios with increasing Reynolds numbers typical of conventional fully developed isotropic turbulence.