A High-Order Conservative Semi-Lagrangian Solver for 3D Free Surface Flows with Sediment Transport on Voronoi Meshes
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A High‑Order Conservative Semi‑Lagrangian Solver for 3D Free Surface Flows with Sediment Transport on Voronoi Meshes Matteo Bergami1 · Walter Boscheri1 · Giacomo Dimarco1 Received: 31 December 2019 / Revised: 1 August 2020 / Accepted: 9 August 2020 © The Author(s) 2020
Abstract In this paper, we present a conservative semi-Lagrangian scheme designed for the numerical solution of 3D hydrostatic free surface flows involving sediment transport on unstructured Voronoi meshes. A high-order reconstruction procedure is employed for obtaining a piecewise polynomial representation of the velocity field and sediment concentration within each control volume. This is subsequently exploited for the numerical integration of the Lagrangian trajectories needed for the discretization of the nonlinear convective and viscous terms. The presented method is fully conservative by construction, since the transported quantity or the vector field is integrated for each cell over the deformed volume obtained at the foot of the characteristics that arises from all the vertexes defining the computational element. The semi-Lagrangian approach allows the numerical scheme to be unconditionally stable for what concerns the advection part of the governing equations. Furthermore, a semi-implicit discretization permits to relax the time step restriction due to the acoustic impedance, hence yielding a stability condition which depends only on the explicit discretization of the viscous terms. A decoupled approach is then employed for the hydrostatic fluid solver and the transport of suspended sediment, which is assumed to be passive. The accuracy and the robustness of the resulting conservative semi-Lagrangian scheme are assessed through a suite of test cases and compared against the analytical solution whenever is known. The new numerical scheme can reach up to fourth order of accuracy on general orthogonal meshes composed by Voronoi polygons. Keywords Conservative semi-Lagrangian · Free surface flows · Sediment transport · Highorder reconstruction · Hydrostatic model Mathematics Subject Classification 35Q35 · 76D05 · 65M08 · 65M25 * Walter Boscheri [email protected] Matteo Bergami [email protected] Giacomo Dimarco [email protected] 1
Department of Mathematics and Computer Science, University of Ferrara, Via Machiavelli 30, I‑44121 Ferrara, Italy
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Vol.:(0123456789)
Communications on Applied Mathematics and Computation
1 Introduction The transport of sediment in rivers, lakes, or shores is particularly relevant in hydraulic engineering for several different reasons [2]. Erosion and deposition zones are generated by sediments which typically cause the modification of the river beds or that of the shores over time. Sediments have an influence on energy production in dams, and they may cause damages and serious risks for the environment, and they are responsible for delivering nutrients and, as opposite, contaminants. For the above reasons, the modeling of such flows, as well as the understanding of their dynamics, i
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