Numerical simulation of sand dune evolution in severe winds

We present a novel approach for numerical simulation of uid ow and sediment transport past evolutionary landforms, with emphasis on sand dunes developing in extreme winds. Time-dependent curvilinear coordinates are employed to fully couple ow aloft with the developing landform. The conservation law that de nes shape of the lower boundary depends on details of local surface stress, thereby favouring a large eddy simulation of the atmospheric boundary layer. The ux-form partial di erential equation for the interface pro le—via saltation and sand avalanches—is formulated as an advection–di usion equation. The latter facilitates discrete integrations using nonoscillatory algorithms—consistent with the nonoscillatory forward-in-time solver, based on MPDATA transport methods, employed to simulate the boundary layer ow aloft. Theoretical discussions are illustrated with numerical experiments that explore the interactive evolution of the dune/atmosphere system. Copyright ? 2005 John Wiley & Sons, Ltd.