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

International audienceHeat transfer in a fully developed turbulent pipe flow is investigated by use of the large eddy simulation technique. Isoflux condition is imposed at the wall. Four Prandtl numbers are considered (0.71,3,5,7) and three Reynolds numbers (5500, 10000, 20000). 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 20000. Validation is achieved by comparing the present predictions to the available results of 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 intantaneaous filtered temperature fields are analyzed

Turbulent heat transfer characteristics of water flow in a rotating pipe

International audienceLarge-Eddy-Simulation of turbulent heat transfer for water flow in rotating pipe is performed, for various rotation ratios (0 < N < 15). The value of the Reynolds number, based on the bulk velocity and pipe diameter, is Re = 5500. The aim of this study is to examine the effect of the rotating pipe on the turbulent heat transfer for water flow, as well as the reliability of the LES approach for predicting turbulent heat transfer in water flow. Some predictions for the case of non-rotating pipe are compared to the available results of literature for validation. To depict the influence of the rotation ratio on turbulent heat transfer, many statistical quantities are analyzed (distributions of mean temperature, rms of fluctuating temperature, turbulent heat fluxes, higher-order statistics). Some contours of instantaneous temperature fluctuations are examined