Wall-Modeling Approaches for Large Eddy Simulations of Natural Convection
(2024) 1st European Fluid Dynamics Conference — Location: Aachen, Germany (16.September.2024)
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- Abstract
- Natural convection is encountered in a plethora of natural phenomena and technological applications.However, in most cases of practical interest, the turbulence intensity (equivalently, the Rayleigh number) is very high. Accordingly, Direct Numerical Simulations are prohibitively expensive with current computational resources. A promising alternative is the Wall-Modeled Large Eddy Simulation (WMLES) approach. According to it, the effects of the unresolved profiles of the flow variables in the near-boundary regions are taken into account by properly modifying the boundary conditions (i.e. via wall models). In the last 25 years, various wall models for the hydrodynamic boundary layers have been developed with satisfactory results. However, much less attention was paid in models for the thermal boundary layers.In the first part of this talk, we examine the performance of models for thermal boundary layers in turbulent convection. For convection at moderately high Rayleigh numbers (Ra=1e8) comparisons are made with results from wall-resolved LES. In our investigations, we considered two cases, namely, convection of liquid water in a cubic box and in an open cavity. In the latter one, the open top boundary is modeled as a free-slip but fixed-temperature plane, which implies the development of a thermal layer but absence of a hydrodynamic one.Additionally, for the case of an open cavity, we elaborate on the effect of the grid resolution on the performance of the thermal models at the free-slip plane.In the second part of the talk, we present results from WMLES of natural convection of water in open cavities and at high Rayleigh numbers,Ra≥5e9. In our presentation, we elaborate on the main properties and structure of the flow, and also comment on the effect of a Prandtl number greater than unity. Additionally,we show results of the statistics of the various flow quantities of interest
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Ceresiat, L., & Papalexandris, M. (2024). Wall-Modeling Approaches for Large Eddy Simulations of Natural Convection. 1st European Fluid Dynamics Conference, Aachen, Germany. https://hdl.handle.net/2078.5/213522