A Hybrid Reduced Order Method for Modelling Turbulent Heat Transfer Problems
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A parametric, hybrid reduced order model approach based on the Proper Orthogonal Decomposition with both Galerkin projection and interpolation based on Radial Basis Functions method is presented. This method is tested against a case of turbulent non-isothermal mixing in T-junction pipe, a common flow arrangement found in nuclear reactor cooling systems. The reduced order model is derived from the 3D unsteady, incompressible Navier-Stokes equations weakly coupled with the energy equation. For high Reynolds numbers, the eddy viscosity and eddy diffusivity are incorporated into the reduced order model with a Proper Orthogonal Decomposition (nested and standard) with Interpolation (PODI), where the interpolation is performed using Radial Basis Functions. Two full-order turbulent modelling techniques, the Large Eddy Simulation (LES) and the Unsteady Reynolds Averaged Navier-Stokes Equations (URANS) are compared showing that the former requires fewer modes for the eddy viscosity field. The reduced order solver, obtained using a URANS full order model, is tested against the full order solver in a 3D T-junction pipe with parametric velocity inlet boundary conditions.
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