Simulation of a collapsing column for dense granular flows
Linda G. Gesenhues1; José J. Camata1; Alvaro L.G.A. Coutinho2
1 High Performance Center and Department of Civil Engineering, Federal University of Rio de Janeiro; 2 High Performance ComCenter and Department of Civil Engineering, Federal University of Rio de Janeiro
doi:10.20906/CPS/CILAMCE2017-0778
Resumo
Turbidity currents are underflows responsible for sediment deposits that generate geological formations of interest for the oil and gas industry. To simulate such geological formations in many situations it is necessary to study dense granular flows. More and more research projects about the rheology and possible constitutive models are published. However, predicting those dense granular flows is still challenging. The viscoplastic flow behavior changes according to the particle concentration. By reaching a certain particle concentration the mud water mixture behaves as a non-Newtonian fluid. This behavior can be expressed by various constitutive rheology models. A model focusing on dense granular flow is the so-called μ(I)-rheology, which is based on an empirical friction model. In the friction model of the dense granular flow the tangential stresses are considered proportional to the normal ones. Therefore, the pressure has a direct influence to the viscosity. This model provides a non-conventional shear-thinning behavior, which is depending on the shear rate and on the local pressure. Due to the complexity and the high nonlinearity oscillation and divergence occur easily. Therefore, regularization is needed, as well as, a careful choice of the simulating parameters. In this study we take a closer look on the regularization and its influence on the results. A collapsing column is simulated using the μ(I)-rheology aiming to create guidelines for the regularization and other characteristics of this specific case. Experiments are done using a Navier-Stokes solver build in libMesh including a variational multiscale environment and adaptive mesh refinement. The results are discussed and limitations of the model are shown.
Palavras-chave: μ(I)-rheology; dense granular flow; non-Newtonian flow; regularization; design of experiments