A finite element technique has been applied to the layer-averaged equations describing a turbidity current which propagates two-dimensionally in deep ambient water. The governing equations form a hyperbolic system of partial differential equations, namely continuity and x- and y-momentum equations for the flow and mass conservation equation for sediment. The two-dimensional modeling of the layer-averaged equations with a finite element method has two important aspects; the dissipative algorithm and the front tracking technique. Since the standard Galerkin method yields spurious oscillations when applied to convection-dominated flows, the dissipative-Galerkin technique having a selective dissipation property is used. Also, in order to track the moving front accurately, a deforming grid generation technique based on the arbitrary Lagrangian-Eulerian approach is employed for the two-dimensional problem. The developed numerical procedure is applied to a decelerating-depositional turbidity current generated in the laboratory experiment by Luthi (1981). Time-dependent profiles for the current thickness and layer-averaged velocity field and volumetric concentration are obtained. The relevant depositional structure by this underflow event is estimated by incorporating the double grid finite element method into the flow algorithm.
All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Water Science and Technology