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NEAR-WALL VORTICITY DYNAMICS IN TURBULENT COMPRESSIBLE FLOWS

Liang Wei
Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario Canada K7L 3N6

Andrew Pollard
Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario Canada K7L 3N6

Аннотация

Neal-wall vorticity dynamics in turbulent compressible channel flows are studied using direct numerical simulation (DNS). The Mach numbers of the three DNS cases are Ma = 0.2, 0.7, and 1.5 respectively. The Reynolds numbers of three cases are ~ 2800, based on the bulk velocity and the half channel width. The cross-correlation between density and spanwise vorticity is high at y+ ~ 4, which is coincident with the peak mean spanwise baroclinicity. The transport equation for the mean product of density and vorticity fluctuations 〈p'ω'i〉 is presented and the distributions of terms in the 〈p'ω'z〉 transport equation indicate that the minima and maxima of the profiles are located around y+ ~ 5. The relationship between pressure gradients and vorticity fluxes for compressible turbulent flows with variable viscosity has been analyzed quantitatively. Some correlations between pressure gradient and vorticity flux are found high very near the wall. The correlation are affected by Mach number and viscosity in this region.