A second order time homogenized model for sediment transport

A multiscale method for the hyperbolic system s governing sediment transport in a subcritical case is developed. The scale separation of this problem is due to the fact that the sediment transport is much slower than flow velocity. We first derive a zeroth order homogenized model and then propose a first order correction. It is revealed that the first order correction for hyperbolic systems has to be applied on the characteristic speed of slow variables in a one dimensional case. In a two dimensional case, besides the characteristic speed, the source term is also corrected. We develop a second order numerical scheme following the framework of heterogeneous multiscale method. The numerical results in both one and two dimensional cases demonstrate the effectiveness and efficiency of our method.