Abo Bibliothek: Guest
Third Symposium on Turbulence and Shear Flow Phenomena
June, 25-27, 2003, International Center, Sendai, Japan

DOI: 10.1615/TSFP3

DNS AND STRUCTURE-BASED MODELING OF ROTATED HOMOGENEOUS SHEAR FLOW

pages 15-20
DOI: 10.1615/TSFP3.30
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ABSTRAKT

Direct numerical simulations of homogeneous turbulence being sheared in a frame rotating about the spanwise are performed for a range of values of the governing parameters. The aim is to clarify the physics of rotated shear flows and to provide a complete database for use by turbulence modelers. One of the main findings of this work is that the equilibrium value of the ratio of the production rate to the dissipation rate (P/ε) of the turbulent kinetic energy is a function of the ratio of the frame rotation rate to the mean shear rate (Ωf/S). This is true even for those values of Ωf/S corresponding to the "unstable regime", where the turbulent kinetic energy, k, and its dissipation rate, ε, grow exponentially in time. This result is contrary to the predictions of the model ε-equation, which in turbulence modeling provides a standard method to transport the second turbulence scale. When the ε-equation is used in conjunction with the the k-equation, P/ε is predicted to be constant and independent of Ωf/S in the unstable regime. Here, we show this to be an artifact of the constant coefficients used in the model ε-equation. When the large-scale enstrophy equation is used in place of the ε-equation, structure-based turbulence models provide excellent predictions for all one-point statistics, including the Reynolds stresses and the variation of P/ε with Ωf/S.

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