自然科学版 英文版
自然科学版 英文版
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中南大学学报(英文版)

Journal of Central South University

Vol. 15    No. 6    December 2008

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Improvement of Prandtl mixing length theory and application in modeling of turbulent flow in circular tubes
LUO Xiao(罗 潇), LIU Ping-le(刘平乐), LUO He-an(罗和安)

College of Chemical Engineering, Xiangtan University, Xiangtan 411105, China

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.

 

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

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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