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Volume 11, issue 10 | Copyright
Geosci. Model Dev., 11, 4069-4084, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Model evaluation paper 10 Oct 2018

Model evaluation paper | 10 Oct 2018

Comparison of dealiasing schemes in large-eddy simulation of neutrally stratified atmospheric flows

Fabien Margairaz1, Marco G. Giometto2, Marc B. Parlange3, and Marc Calaf1 Fabien Margairaz et al.
  • 1University of Utah, Department of Mechanical Engineering, Salt Lake City, UT 84112, USA
  • 2Columbia University, Civil Engineering and Engineering Mechanics, New York, NY 10027, USA
  • 3Monash University, Department of Civil Engineering, Clayton, VIC 3800, Australia

Abstract. Aliasing errors arise in the multiplication of partial sums, such as those encountered when numerically solving the Navier–Stokes equations, and can be detrimental to the accuracy of a numerical solution. In this work, a performance and cost analysis is proposed for widely used dealiasing schemes in large-eddy simulation, focusing on a neutrally stratified, pressure-driven atmospheric boundary-layer flow. Specifically, the exact 3∕2 rule, the Fourier truncation method, and a high-order Fourier smoothing method are intercompared.

Tests are performed within a newly developed mixed pseudo-spectral finite differences large-eddy simulation code, parallelized using a two-dimensional pencil decomposition. A series of simulations are performed at varying resolution, and key flow statistics are intercompared among the considered runs and dealiasing schemes.

The three dealiasing methods compare well in terms of first- and second-order statistics for the considered cases, with modest local departures that decrease as the grid stencil is reduced. Computed velocity spectra using the 3∕2 rule and the FS method are in good agreement, whereas the FT method yields a spurious energy redistribution across wavenumbers that compromises both the energy-containing and inertial sublayer trends. The main advantage of the FS and FT methods when compared to the 3∕2 rule is a notable reduction in computational cost, with larger savings as the resolution is increased (15% for a resolution of 1283, up to a theoretical 30% for a resolution of 20483).

Publications Copernicus
Short summary
In this project, we compare three different approaches to integrate the fluid-motion equations when applied to solve atmospheric flow dynamics. Differences between the three methods reside in accuracy as well as computational cost. The results illustrate that there is an intermediate solution that performs well in terms of computational cost while at the same time producing good enough results, as long one is not interested in the smallest turbulent scales.
In this project, we compare three different approaches to integrate the fluid-motion equations...