Projet ANR-07-BLAN-0180 – Formation and : Formation and migration of granular dunes in closed channels
Programme : Blanc (BLANC) 2007
Année de financement : 2007
Coordinateur du projet : INSTITUT NATIONAL POLYTECHNIQUE DE TOULOUSE (INSTITUT NATIONAL POLYTECHNIQUE DE TOULOUSE)
Partenaires : Institut national polytechnique de Toulouse; Aix-Marseille université
Montant : 280000.0 euros
Date de début : 2007
Durée : 36 mois
Résumé : In many industrial processes as well as in the natural environment, a liquid flows over an erodible bed of particles. We propose a study of the particle transport which results from the shearing of the bed, in the particular case of closed pipes or channels. The two partners have already an expertise in the field (PhD theses, publications) and also contacts with the petroleum industry. Two different situations may occur: (i) that of a continuous bed, and (ii) that of isolated heaps of particles, separated by regions of smooth pipe wall. In the first situation, the prominent feature is the instability of the flat bed which results in ripple and dune formation; this instability, although well known, is not well understood; it will be studied experimentally and theoretically by the partner 2 at IUSTI (Marseille). In the second situation, isolated heaps have the characteristic shape of crescent dunes, whose propagation, merging and splitting have not been studied yet; these dunes will be studied by partner 1 at IMFT (Toulouse). In both situations, the main objective is to extract from experiments ideas, characteristic scales and scaling laws, for modelling purposes. The algebraic power laws used until now to describe the particle flux are indeed the weak part of the present modelling; some improvements have been recently proposed (two-phase modelling, erosion and deposition scales), which will be developed during the project. Attention will also be paid to the transitional regime, where a continuous bed and a field of isolated dunes may coexist at different places in the channel or alternate in time at the same place.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          ...