RANS model development on temperature variance in conjugate heat transfer

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Abstract

In this study we consider modelling the generation of thermal fluctuations in turbulent flows and their subsequent propagation across surrounding solid walls. The aim and original contribution here, is the development of a RANS model of turbulent conjugate heat transfer, which is applicable across a range of different fluids and different combination of fluid and solid thermal properties. Within the RANS approach this is achieved by focusing on the transport equations for the temperature variance and its dissipation rate across the solid walls which bound the flow region. Some initial such modelling work was reported by Craft et al [12], although existing data available at the time, used to validate their model, was rather limited. Further DNS studies have emerged since, covering a wider range of operating parameters, determined by independent dimensionless groups like the fluid Prandtl number and the ratios between fluid and solid thermal properties. In this investigation we make use of this wider range of DNS data, to advance our understanding of the processes involved and to revise and extend the capabilities of the model of Craft et al including a more physical fluid-solid interface condition on the dissipation of thermal fluctuations and a dependence of model coefficients on Prandtl number. The resulting model is shown to successfully reproduce the penetration of thermal fluctuations into solid regions, and their subsequent decay across the solid, for a wide range of fluid to solid thermal property ratios, and Prandtl numbers, thereby bringing a step change to RANS capabilities in turbulent conjugate heat transfer analysis.

Bibliographical metadata

Original languageEnglish
JournalJournal of Turbulence
Publication statusAccepted/In press - 2 Dec 2020