Improvement of Prandtl mixing length theory and application in modeling of turbulent flow in circular tubes

来源期刊：中南大学学报(英文版)2008年第6期

论文作者：罗潇 刘平乐 罗和安

文章页码：774 - 778

Key words：turbulent flow; Prandtl mixing length; time-smoothed velocity; eddy viscosity; friction factor

Abstract: In order to correctly predict tube cross section time-smoothed velocity distribution, friction factor and mass transfer behavior, two models for turbulent flow in circular tubes based on classical Prandtl mixing length theory and a modified mixing length were established. The results show that the modified mixing length includes the introduction of a damping function for the viscous sublayer and the second-order derivative to approximate eddy velocity. The calculated dimensionless time-smoothed velocity from the model based on Prandtl mixing length is much better than the result from the concept of eddy viscosity. The calculated eddy viscosity from the model based on modified mixing length is much better than the result from the model based on the classical Prandtl mixing length theory. And the friction factor calculated from the model based on the modified mixing length agrees well with the reported empirical relationships.

基金信息：the National Natural Science Foundation of China
the Natural Science Foundation of Hunan Province, China