Large eddy simulation of turbulent heat transfer in pipe flows with respect to Reynolds and Prandtl number effects

摘要

Heat transfer in a fully developed turbulent pipe flow is investigated by the use of the large eddy simulation technique. Isoflux condition is imposed at the wall. Four Prandtl numbers are considered (0.71, 3, 5, and 7) and three Reynolds numbers (5,500, 10,000, and 20,000). The effects of Reynolds and Prandtl numbers on turbulent heat transfer in pipe flow are investigated in order to obtain a more detailed knowledge of the thermal field in circular pipe flow. The objective of this study is also to examine the effectiveness of the large eddy simulation approach for predicting the turbulent heat transfer at different Prandtl numbers larger than 0.71, for various Reynolds numbers up to 20,000. Validation is achieved by comparing the present predictions to the available results of the literature. The effects of Prandtl and Reynolds numbers on many statistical quantities, such as mean temperature profiles, RMS of fluctuating temperature, turbulent heat fluxes, higher-order statistics, and heat transfer coefficient, are examined.Visualizations of instantaneous filtered temperature fields are analyzed.