Numerical simulation of small-scale mixing processes in the upper ocean and atmospheric boundary layer

International Conference on Computer Simulation in Physics and Beyond 2015

物理学;计算机科学

Druzhinin, O.^1 ; Troitskaya, Yu^1 ; Zilitinkevich, S.^2

Institute of Applied Physics RAS, Nizhny Novgorod, Russia^1

Finnish Meteorological Institute, Helsinki, Finland^2

关键词: Bulk coefficients;    Closure assumptions;    Internal gravity waves;    Reynolds-averaged navier-stokes simulations;    Small scale turbulence;    Small-scale mixing;    Small-scale process;    Turbulent mixing;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/681/1/012027/pdf
DOI  :  10.1088/1742-6596/681/1/012027

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

The processes of turbulent mixing and momentum and heat exchange occur in the upper ocean at depths up to several dozens of meters and in the atmospheric boundary layer within interval of millimeters to dozens of meters and can not be resolved by known large- scale climate models. Thus small-scale processes need to be parameterized with respect to large scale fields. This parameterization involves the so-called bulk coefficients which relate turbulent fluxes with large-scale fields gradients. The bulk coefficients are dependent on the properties of the small-scale mixing processes which are affected by the upper-ocean stratification and characteristics of surface and internal waves. These dependencies are not well understood at present and need to be clarified. We employ Direct Numerical Simulation (DNS) as a research tool which resolves all relevant flow scales and does not require closure assumptions typical of Large-Eddy and Reynolds Averaged Navier-Stokes simulations (LES and RANS). Thus DNS provides a solid ground for correct parameterization of small-scale mixing processes and also can be used for improving LES and RANS closure models. In particular, we discuss the problems of the interaction between small-scale turbulence and internal gravity waves propagating in the pycnocline in the upper ocean as well as the impact of surface waves on the properties of atmospheric boundary layer over wavy water surface.