Large-Eddy Simulation of thermal striping in WAJECO and PLAJEST experiments with TrioCFD
Abstract
This benchmark exercise is being performed under the auspices of an international collaboration on thermal hydraulics for sodium-cooled fast reactor development with participation from the Japan Atomic Energy Agency (J.A.E.A.), the U.S. Department of Energy (D.O.E.), and the French Commissariat a l'energie Atomique et aux energies Alternatives (C.E.A.). It is based on experiments performed to study the effects of thermal striping where three differentially heated jets mix inside a cavity. They were carried out either in water or in liquid sodium and provided velocity and temperature data. The object of this paper is to predict numerically the results of these experiments and make comparisons with available measured data. The numerical simulations are led using the CEA simulation code Trio_U. The Large-Eddy Simulation model is applied for the analyses. A computational domain reproducing the test sections is created. The discretization of the equations is based on unstructured meshes and the resolution on a finite-volume approach. Coupled heat transfer between fluid and a metal test plate is considered. Overall, the numerical results achieve a good agreement with the experiments as well for the time-averaged fields as for the power spectrum densities of temperature fluctuations inside the fluid and the structure. A near-wall mesh refinement provides an obvious improvement of the accuracy of predicted temperature fluctuations.
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