EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Numerical simulation of the evening transition in the atmospheric boundary layer using LES and RANS models

Ekaterina Tkachenko1, Andrey Debolskiy1,2,3, and Evgeny Mortikov1,2,4
Ekaterina Tkachenko et al.
  • 1Lomonosov Moscow State University, Moscow, Russian Federation
  • 2Moscow Center for Fundamental and Applied Mathematics, Moscow, Russian Federation
  • 3A.M. Obukhov Institute of Atmospheric Physics RAS, Moscow, Russian Federation
  • 4Marchuk Institute of Numerical Mathematics RAS, Moscow, Russian Federation
This study investigates the dynamics of the evening transition in the atmospheric boundary layer (ABL) diurnal cycle, specifically the decay of the turbulent kinetic energy (TKE) taking place there. Generally, the TKE decay is assumed to follow the power law E(t) ~ t-α, where E(t) and t are normalized TKE and normalized time, respectively, and the parameter α determines the decay rate.

Two types of ABL numerical modeling are compared: three-dimensional large-eddy simulation (LES) models and one-dimensional Reynolds-averaged Navier-Stokes (RANS) models. The evening transition is simulated through facilitating the formation of the convective boundary layer (CBL) by having a constant positive surface heat flux, and the subsequent decay of the CBL when the surface heat flux is decreased.

Several features of this process have been studied in relative depth, in particular the TKE decay rate at different stages of the evening transition, the sensitivity of the results to the domain size, and the dynamics of the large- and small-scale turbulence during the transition period. LES experiments with different setups were performed, and the results were then compared to those obtained through RANS experiments based on the k-epsilon model (a two-equation model for TKE and dissipation rate, where model constants are chosen to allow for correct simulation of SBL main properties [1], as well as CBL growth rate [2]).

This study was funded by Russian Foundation of Basic Research within the project N 20-05-00776 and the grant of the RF President within the MK-1867.2020.5 project.

1. Mortikov E. V., Glazunov A. V., Debolskiy A. V., Lykosov V. N., Zilitinkevich S. S. Modeling of the Dissipation Rate of Turbulent Kinetic Energy // Doklady Earth Sciences. 2019. V. 489(2). P. 1440-1443

2. Burchard H. Applied Turbulence Modelling in Marine Waters. Berlin, Germany: Springer, 2002. P. 57-59

How to cite: Tkachenko, E., Debolskiy, A., and Mortikov, E.: Numerical simulation of the evening transition in the atmospheric boundary layer using LES and RANS models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14787,, 2021.

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