ISSN Online: 2377-424X
International Heat Transfer Conference 12
Recent Developments in Turbulent Heat Transfer Modelling for Complex Flows at Various Prandtl Numbers
要約
We present some recent developments in turbulence models for heat transfer in complex flows with different Prandtl numbers. First, we outline a linear two-equation heat-transfer model for wall turbulent thermal fields. The model reproduces the correct wall-limiting behavior of velocity and temperature under arbitrary wall thermal conditions. The sample model appraisal is given with two different typical thermal fields, which often occur in engineering applications, in wall turbulent shear flows. Secondly, we describe the methodology for constructing a heat-transfer model for a variety of Prandtl-number fluids. The most recent model incorporates new velocity and time scales to represent various sizes of eddies in velocity and thermal fields with different Prandtl numbers. Fundamental properties of the model are first verified in basic flows under arbitrary wall thermal boundary conditions and next in backward-facing step flows at various Prandtl numbers through a comparison of the predictions with the DNS and measurements. We show that the predicted heat transfer rate coincides with the reliable empirical formulas and experimental data with high accuracy. Finally, we demonstrate the current modelling methodology to include strong anisotropic thermal features such as flow separation and reattachment, surface transpiration, and rotation effects, which are essential to practical applications.