Mixing for planar turbulent wakes in passively stratified media
A.G. Demenkov1,2, G.G. Chernykh3
1Kuteteladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State technical University, Novosibirsk, Russia
3Federal Research Center for Information and Computational Technologies, Novosibirsk, Russia
Keywords: planar turbulent wake in a passively stratified medium, semiemperical models for turbulence, mathematical simulation
Abstract
The flow pattern in the planar turbulent far wake past a body in a passively stratified medium is investigated by applying a mathematical model including the following features: Rodi’s algebraic approximations for Reynolds stress, the differential equation for transfer of a deficit in the mean velocity longitudinal component, the balance of the turbulence energy and its dissipation rate, fluid density deficit, vertical component of the mass flux vector, and the equation for dispersion in the turbulent fluctuations of density. The far-wake approximation is used in this problem. The paper discusses an issue of the local-equilibrium truncation taken for the two last equations. We compare the solutions of self-similar degeneration of the density field characteristics for a case of a classical turbulent wake behind a towed cylinder and for a case of momentumless turbulent wake. The results of numerical experiments were a foundation for interpreting the observed high error while using the locally-equilibrium truncation equation for transfer of the density fluctuations dispersion.
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