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A large eddy simulation of a planar channel flow with significant heat transfer at a low Mach number was performed to study effects of fluid property variations on the near-wall turbulence structure. A compressible dynamic subgrid scale model was used to model the residual-scale turbulence. Two low Reynolds number channel flows with one wall heated and one wall cooled at temperature ratios of 1.02 and 3.0 were simulated to study the effects of property variations at low Mach number. Several features of the flow were observed to vary with the heat transfer level including velocity and temperature rms values. Specifically, the temperature-velocity correlations were found to exhibit stronger dependency on heat transfer rate. At the higher heat transfer rate, density fluctuations at levels characteristic of flows at much higher Mach numbers were observed. Heating appeared to enhance velocity fluctuations whereas density and temperature percentage fluctuations were greatest near the cooled wall when scaled by their local mean values.

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sponsored by the American Institute of Aeronautics and Astronautics Orlando, Florida, July 6-9, 1993https://ntrs.nasa.gov/search.jsp?R=19940012655 2019-04-27T11:28:58+00:00ZAIA.A93-3368 ON SOLVING THE COMPRESSIBLE NAVIER-STOKES EQUATIONS FOR UNSTEADY FLOWS AT VERY LOW MACH NUMBERS R.H.Pletcher Institute forCompmational Mechamics in Prolmlsion ABSTRACTThe properties of a preconditioned, coupled, stronglyimplicit finite-difference scheme for solving the compressible Navier-Stokes equations in primitive variables are investigated for two unsteady flows at low speeds, namely the impulsively started driven _vity .and the start.up of pipe flow. For the shear-driven rarity now, me computanonal eslort was observed to be nearly independent of Mach number, especially at the low end of the range considered. This Much number independence was also observed for steady pipe flow calculations; however, rather different conclusions were drawn for the unsteady calculations. In the pressure-driven pipe startup problem, the compressibility of the fluid_began to significantly influence the physics of the flow develolmumt at quite low Mach numbers. "t_e present scheme w_ ouserved to produce the expected _ties of completely incompressible flow when the Macn numtx:r was set at very low values. Good agreement with incompressible results available in the literature was observed.