# Isotropic Turbulence

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 June 27, 2003, 08:24 Isotropic Turbulence #1 gorka Guest   Posts: n/a Hi, I'm a bit confused with the isotropic assumption in turbulence modelling. I've read in some references that in isotropic turbulence: (Tau = Reynolds stresses) Tau(1,1) = Tau(2,2) = Tau(3,3) and Tau(i,j) = 0 for any i different from j. but I can't understand how this result can be achieved with the Boussinesq Hypothesis: Tau(i,j)= Mu_t*(diff(Ui)/diff(xj) + diff(Uj)/diff(xi)) -2/3*rho*k*D_Kronecker(i,j) Moreover, Wilcox refers to isotropy in this sense: Tau(i,j)/S(i,j) = C(mu_t) (S = Mean Strain Tensor) that has nothing to do with the former definition!! Can anyone help me, please? Thank you very much, Gorka

 June 30, 2003, 15:39 Re: Isotropic Turbulence #2 hall Guest   Posts: n/a I think you maybe mess up several stress tensor definition. In isotropy turbulence, stress tensor = , it is a seconde-order correlation. And the tau(1) = tau(2) = tau(3) is true In Boussinesq Hypothesis, it is a one-equation model of RANS(Raynolds averaged N-S), the stress tensor is the averaged fluctuating velocity (overbar of (u'u') )

 June 30, 2003, 15:41 Re: Isotropic Turbulence #3 hall Guest   Posts: n/a In isotropy turbulence, stress tensor = average of (u_i*u_j) huh, the system eat my equation

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