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Analysis of Model Variance for Ensemble Based Turbulence Modeling

Jiang, Nan
Kaya Merdan, Songül
Layton, William
This report develops an ensemble or statistical eddy viscosity model. The model is parameterized by an ensemble of solutions of an ensemble-Leray regularization. The combined approach of ensemble time stepping and ensemble eddy viscosity modeling allows direct parametrization of the turbulent viscosity co-efficient. We prove unconditional stability and that the model's solution approaches statistical equilibrium as t -> infinity; the model's variance converges to zero as t -> infinity. The ensemble method is used to interrogate a rotating flow, testing its predictability by computing effiective averaged Lyapunov exponents.