A high-resolution 2-DH numerical scheme for process-based modeling of 3-D turbidite fan stratigraphy

A generic three-dimensional process-based model is presented, aimed at simulation of the construction of turbidite fan stratigraphy by low-density turbidity current events. It combines theoretical formulations on density flow and sediment transport of multiple grain sizes to simulate 2-DH turbidity current flow and sedimentation over arbitrary topography. The model is solved on a rectangular grid by means of a robust and efficient second-order finite-difference approximation. A high-resolution shock-capturing technique is employed to accurately model the speed and shape of the discontinuous flow front. In this paper, the implementation of such a high-resolution scheme is explained in detail. Efficiency and robustness of the numerical solution are tested by comparing modeled flow behavior and sedimentation to measurements from flume-tank experiments in which turbidity currents interacted with obstacles representative of a tectonically deformed basin floor. Results illustrate that the interaction of the flow with the obstacles is realistically simulated, and that the experimental deposit geometries are reasonably well reproduced. Stability of the model depends on the length of the computational time step and the properties of the adopted flux limiter function. Run time of the simulations is somewhat shorter than the real-time duration of the experiments, which is deemed acceptable considering the small computational time step which must be adopted to keep the model stable at this small scale. At the much larger scale of real-world turbidity currents a much larger computational time step can be adopted, which will speed up simulation considerably.