Article: Development of a model for unsteady conjugate heat transfer simulations Journal: Progress in Computational Fluid Dynamics, An International Journal (PCFD) 2019 Vol.19 No.2 pp.69 - 79 Abstract: Recent developments in CFD simulations go towards higher accuracy by using time-resolved simulations instead of steady RANS simulations and adding solid structures to the simulation instead of assuming constant wall temperatures or heat fluxes at wall boundaries. This means a very large number of time steps are necessary to both accurately resolve the turbulent fluctuations in the fluid parts and have a converged temperature field in the solid parts of the computational domain. Another problem in near-wall heat transfer is the often used assumption of a constant turbulent Prandtl number, which is not correct for many flow configurations. The present work therefore focuses on the development of a methodology for accelerated unsteady conjugated heat transfer simulations. Furthermore, the implementation of a near-wall heat transfer model that does not rely on a constant turbulent Prandtl number was evaluated. The models are implemented in the CFD solver ANSYS CFX. The validation of the turbulent heat transfer model shows improved agreement with the experimental results compared to a constant turbulent Prandtl number approach. The improved unsteady conjugate heat transfer methodology gives the same accuracy of the results as the implicit unsteady conjugate heat transfer model but with considerable reduction of the computational time. Inderscience Publishers - linking academia, business and industry through research

Title: Development of a model for unsteady conjugate heat transfer simulations

Authors: Stefan Voigt; Berthold Noll; Manfred Aigner

Addresses: German Aerospace Center (DLR), Institute of Combustion Technology, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany ' German Aerospace Center (DLR), Institute of Combustion Technology, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany ' German Aerospace Center (DLR), Institute of Combustion Technology, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany

Abstract: Recent developments in CFD simulations go towards higher accuracy by using time-resolved simulations instead of steady RANS simulations and adding solid structures to the simulation instead of assuming constant wall temperatures or heat fluxes at wall boundaries. This means a very large number of time steps are necessary to both accurately resolve the turbulent fluctuations in the fluid parts and have a converged temperature field in the solid parts of the computational domain. Another problem in near-wall heat transfer is the often used assumption of a constant turbulent Prandtl number, which is not correct for many flow configurations. The present work therefore focuses on the development of a methodology for accelerated unsteady conjugated heat transfer simulations. Furthermore, the implementation of a near-wall heat transfer model that does not rely on a constant turbulent Prandtl number was evaluated. The models are implemented in the CFD solver ANSYS CFX. The validation of the turbulent heat transfer model shows improved agreement with the experimental results compared to a constant turbulent Prandtl number approach. The improved unsteady conjugate heat transfer methodology gives the same accuracy of the results as the implicit unsteady conjugate heat transfer model but with considerable reduction of the computational time.

Keywords: CFD; conjugate heat transfer; unsteady CHT simulation; turbulent heat transfer modelling.

DOI: 10.1504/PCFD.2019.098465

Progress in Computational Fluid Dynamics, An International Journal, 2019 Vol.19 No.2, pp.69 - 79

Accepted: 30 Apr 2017
Published online: 25 Mar 2019 *

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Title: Development of a model for unsteady conjugate heat transfer simulations

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