Diffusion-Induced Effects in a Stratified Fluid Around a Motionless Wedge

Abstract

The paper is devoted to study continuously stratified fluid flows in field of external mass forces accounting for dissipative factors, viscosity and diffusion. The mathematical model and the numerical implementation method permitting to study simultaneously all the elements of the internally multi-scale stratified currents without additional hypotheses and links are developed on the basis of the fundamental system of equations. Criteria for the reconstruction and optimization of the grids are formulated based on the scale analysis of systems of equations. Influence edge effects upon the current structure is shown. In a stably stratified environment, the integral force inducing self-motion of a free wedge along the neutral buoyancy horizon towards the top is formed by pressure deficit in the adjacent jet streams. In accordance with the results of the experiments, the body in a stably stratified medium moves toward its top. Thin fluid jet streams, formed along each side of the wedge, generate the internal waves in the areas of convergence with the corner points. These waves form thin layers. The transformation of the disturbance field of the medium at the onset of the forced slow motion of the wedge on the neutral buoyancy horizon, the formation of the upstream perturbation, the field of internal waves, the vortices and the wake is traced. The complex structure of the fields of various physical quantities and their gradients is visualized, and the intrinsic time and spatial scales of the structural flow components are determined..

Formation of the Vorticity Field of a Stratified Fluid Near a Wedge

“…= 0.1 m, h = 2 cm. They are close to the experiments[12] that were carried out at the Institute for Problems of Mechanics of the Russian Academy of Sciences. The calculation results of diffusion induced flows on the motionless wedge were in a qualitative agreement with the laboratory ones.…”

Calculation of Nonuniform Fluid Flows in a Gravity Field

“…The detailed study of the diffusion induced flows structure and dynamics were carried out numerically e.g. in [15,16]. Formation of an intensive zone of intensive depression in front of the leading vertex of the wedge is responsible for generation of propulsive mechanism.…”