Topical Problems of Fluid Mechanics


Institute of Thermomechanics AS CR, v.v.i.	CTU in Prague Faculty of Mech. Engineering Dept. Tech. Mathematics	MIO Université du Sud Toulon Var - AMU - CNRS - IRD	Czech Pilot centre ERCOFTAC

Diffusion-Induced Effects in a Stratified Fluid Around a Motionless Wedge
N. F. Dimitrieva, Yu. D. Chashechkin
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.
Keywords:
stratification, wedge, numerical simulation

Fulltext: PDF DOI: https://doi.org/10.14311/TPFM.2018.008

In Proceedings Topical Problems of Fluid Mechanics 2018, Prague, 2018 Edited by David Šimurda and Tomáš Bodnár, pp. 57-64 ISBN 978-80-87012-65-9 (Print) ISSN 2336-5781 (Print)