The von Karman constant determined by large eddy simulation

X. M. Cai, D. G. Steyn

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20 Citations (Scopus)


Explores the extent to which the logarithmic region of the adiabatic atmospheric boundary layer can be modeled using a three-dimensional large eddy simulation. A value of the von Karman constant (κLES) is obtained by determining the slope of a logarithmic portion of the velocity profile. Its numerical value is found the be dependent on the value of the Smagorinsky-Model Reynolds number, ReSM: the value of κLES increases with ReSM. Results indicate that κLES approaches a value of 0.35 as ReSM reaches about 7.75×105 for the largest domain. The sensitivity of κLES to the profile region over which it is evaluated has been tested. Results show that κLES is not sensitive to the depth of this evaluation region when we employ five grids above the sub-grid buffer layer where sub-grid-scale effects dominate. The maximum κLES is obtained when the lower boundary of the evaluation region is just above the top of the sub-grid-scale buffer layer. This result is consistent with modelled mean speed and resolved-scale stress profiles.

Original languageEnglish
Pages (from-to)143-164
Number of pages22
JournalBoundary-Layer Meteorology
Issue number1-2
Publication statusPublished - 1 Jan 1996

ASJC Scopus subject areas

  • Atmospheric Science


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