Computational and experimental investigation of the shear stress on a coastal foredune *

Flow over coastal dunes can be an important source of particulate matter to the atmosphere from dust emissions. For onshore winds, a foredune can be the first major obstacle coastal winds encounter and can modify the developing boundary layer. We conduct numerical and experimental investigations of the flow over a mature foredune located in Oceano Dunes State Vehicular Recreation Park, Oceano CA. High resolution topography of approximately 10 cm resolution was acquired through photogrammetry and inlet boundary condition for a CFD was developed from flow measurements from multiple sonic anemometers mounted on a mobile tower. An additional mobile tower collected validation data at four locations throughout the foredune. Time averaged flow simulations using a K-omega SST turbulence model allow for the quantification of shear, which can be used to predict sediment mobilization. Flow visualization reveals that natural plant stabilization of the foredune results in highly aerodynamic forms with little flow separation.