1065 PRODUCTION AND TRANSPORT OF TURBULENT KINETIC ENERGY IN FRACTAL-GENERATED TURBULENCE

抄録

Production and transport of turbulent kinetic energy in multiscale/fractal-generated turbulence is investigated in a wind tunnel. A fractal grid, which is composed of fractal elements with square shapes, is placed at the inlet of the test section. The Reynolds numbers (Re0) based on the thickness of the biggest grid bar t0 and the inflow velocity U∞ are set to 5,900. The spatial developments of cross-sectional profiles of turbulent kinetic energy K, dissipation rate of K, ε, advection A*, production ?*, triple-correlation transport Γ*, pressure transport Π*, and viscous diffusion D* terms in the transport equation of K are measured by using a hot wire anemometer with I and X type probes. The results show that in the upstream region, ? = ?*/ε at the region downstream of the interior of the biggest grid bar has a value larger than that around the centerline, and turbulent kinetic energy at this region is transported to the central and outward regions by Γ = Γ*/ε . In the decay region, ? at the aforementioned region has a low value and turbulent kinetic energy at this region is mainly transported outward rather than to the central region by Γ.