Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations

S. Nishizawa, H. Yashiro, Y. Sato, Yoshiaki Miyamoto, H. Tomita

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

We examine the influence of the grid aspect ratio of horizontal to vertical grid spacing on turbulence in the planetary boundary layer (PBL) in a large-eddy simulation (LES). In order to clarify and distinguish them from other artificial effects caused by numerical schemes, we used a fully compressible meteorological LES model with a fully explicit scheme of temporal integration. The influences are investigated with a series of sensitivity tests with parameter sweeps of spatial resolution and grid aspect ratio. We confirmed that the mixing length of the eddy viscosity and diffusion due to sub-grid-scale turbulence plays an essential role in reproducing the theoretical -5/3 slope of the energy spectrum. If we define the filter length in LES modeling based on consideration of the numerical scheme, and introduce a corrective factor for the grid aspect ratio into the mixing length, the theoretical slope of the energy spectrum can be obtained; otherwise, spurious energy piling appears at high wave numbers. We also found that the grid aspect ratio has influence on the turbulent statistics, especially the skewness of the vertical velocity near the top of the PBL, which becomes spuriously large with large aspect ratio, even if a reasonable spectrum is obtained.

Original languageEnglish
Pages (from-to)3393-3419
Number of pages27
JournalGeoscientific Model Development
Volume8
Issue number10
DOIs
Publication statusPublished - 2015 Oct 28
Externally publishedYes

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Large Eddy Simulation
large eddy simulation
Large eddy simulation
Aspect Ratio
Boundary Layer
Aspect ratio
Turbulence
Boundary layers
boundary layer
turbulence
Grid
energy
skewness
Energy Spectrum
Numerical Scheme
Slope
eddy
spacing
spatial resolution
viscosity

ASJC Scopus subject areas

  • Modelling and Simulation
  • Earth and Planetary Sciences(all)

Cite this

Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations. / Nishizawa, S.; Yashiro, H.; Sato, Y.; Miyamoto, Yoshiaki; Tomita, H.

In: Geoscientific Model Development, Vol. 8, No. 10, 28.10.2015, p. 3393-3419.

Research output: Contribution to journalArticle

Nishizawa, S. ; Yashiro, H. ; Sato, Y. ; Miyamoto, Yoshiaki ; Tomita, H. / Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations. In: Geoscientific Model Development. 2015 ; Vol. 8, No. 10. pp. 3393-3419.
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