Modeling and Analysis of Quasi-2D Turbulence Dynamics in Shallow Waters

Introduction. The work is devoted to the study of the generation and development of turbulent structures in shallow-water flows. For optimal water resource management, it is necessary to know what the consequences will be if the flow system changes as a result of human intervention. Basically, all fluid flows that relate to the practice of civil engineering are turbulent in nature. These are, for example, river and channel flows, tidal currents in the oceans and coastal seas. Shallow currents in the environment often include a wide range of vortex scales, ranging from micro-scale vortices to large-scale coherent structures with horizontal length scales that far exceed the depth of water (L >> H). The existence of such large structures is a typical characteristic of turbulence in shallow flow. This indicates the need for a systematic analysis of the problem, as well as modeling of such complex formalized systems. The purpose of this work is to model and analyze the dynamics of quasi-2D turbulence structures.

Materials and Methods. Large-scale quasi-2D coherent structures (2 DCS) are investigated depending on the source and localization in the liquid column. Turbulent flows in the channel satisfying incompressible Navier-Stokes equations are considered. The numerical experiment was carried out on the basis of the “large eddy simulation” (LES) approach.

The Results of the Study. Scenario of the dynamics of quasi-2D turbulence structures of the coastal zone is constructed, the formation of vortex structures is predicted.

Discussion and Conclusions. The development of two-dimensional turbulence in shallow flows illustrates the processes that control quasi-two-dimensional turbulence, including the merging of individual vortices. The main mechanism controlling the decay of 2DCS is the loss of energy due to friction on the bottom, while the larger the size of the vortex relative to the depth, the faster the direct dissipation of its kinetic energy occurs.

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