MORPHOLOGIC PREDICTION FROM COUPLED GRAIN-SCALE AND EQUILIBRIUM-SCALE MODELS

摘要

We have implemented two schemes that use sediment transport predictions from a detailed discrete particle model (DPM) to compute longterm, equilibrium morphology. This analysis directly couples processes acting at the grain scale (mm) to the scale of a nearshore profile (km). In the first scheme, the DPM was applied iteratively to find an equilibrium profile that resulted primarily from a balance between offshore-directed down-slope transport and onshore-directed transport driven by strong pressure gradients acting on relatively coarse sand grains. In the second scheme, the predictions from the first scheme were parameterized and the parameterized model was applied iteratively. In this case equilibrium resulted from a balance between down slope transport and a parameterization based on near bed slope and flow velocity and acceleration skewnesses. While both approaches yielded qualitatively similar results, the parameterization approach had the advantage of filtering numerical noise as well as much-reduced computational effort.