Hydrodynamic instabilities in shallow reservoirs

Abstract

This Master's thesis is devoted to the study of ?ows in shallow reservoirs. The main purpose is to enhance the knowledge of the di?erent ?ow regimes in order to improve the prediction of deposits and thus the reservoir management. To do this, two points are covered in this thesis: the in?uence of geometric parameters (length and width of the reservoir) on main characteristics of meandering ?ows and the applicability of thermodynamic principles to predict the ?ow regime in reservoirs. Concerning the ?rst point, three experiments were performed in a shallow horizontal ?ume, the ?rst experiment being used to validate the experimental protocol. For each experiment, the surface velocity ?elds were measured by Large-Scale Particle Image Velocimetry (LSPIV) and the main characteristics of measured meandering ?ows such as the characteristic lengths or the Strouhal number were obtained using a Proper Orthogonal Decomposition (POD). Finally, it was shown that for a given ?ow regime, the characteristics of the ?ow do not depend on the geometry but only on the shallowness of the reservoir. In the second part, two analytical models were developed to model symmetric and asymmetric ?ows. Mass and momentum balance equations were established and the power developed by the shear force was determined for each model and compared. Based on this comparison, it was shown that the principle of maximum power could be used to determine the ?ow regime in reservoirs.