Residual-based variational multiscale simulation of erosion using libMesh

Malú Grave¹; José J. Camata¹; Alvaro L. G A. Coutinho¹

¹ High Performance Computing Center and Dept. of Civil Engineering, UFRJ

doi:10.20906/CPS/CILAMCE2017-0370

Resumo

Sediment transport induced by fluid flows is a field of great interest in modern hydraulic science due to its great importance in engineering applications. Flood control, canals for irrigation, navigation and other projects are strongly affected by moving sediments. Depending on the intensity of the flow, erosion can appear at the bottom, for example. It occurs when the sediment bed changes by losing its mass as a consequence of sediment entrainment into suspension. Once out of the bottom, the finer sediments can be maintained in suspension by turbulence or deposited due to the gravitational acceleration. These phenomena are implemented as numerical models in libMesh, an open finite element library that provides a framework for numerical simulations in multiphysics. Here, the mathematical model results from the incompressible Navier-Stokes equation combined with an advection-diffusion transport equation for suspended sediments. The Navier-Stokes equation is treated with the residual-based variational multiscale finite element formulation while the advection-diffusion transport equation uses a stabilized method and a discontinuity capturing formulation. An empirical model is used to represent the entrainment rate. Special boundary conditions at the bottom are introduced to take into account sediments entrainment, as well as deposition. Two well-documented test cases where experimental data are available are used to validate the model employed in the present study. Results are analyzed and discussed.

Palavras-chave: Computational fluid dynamics; Finite Element; Sediment transport