CFD Modelling and Field Observations of Flow over Scarps

Patrick Hesp, Thomas Smyth
Flinders University, Adelaide, SA, Australia


Scarps or vertical to near-vertical cliffs are common on coastal dunes, particularly foredunes following wave erosion. They also occur in many aeolian environments and may be associated with echo dunes and climbing and clifftop dunes. Only a few studies have been conducted in dune landscapes on the flow over scarps or cliffs, and very few studies have been conducted via computational fluid dynamics (CFD). We present a CFD study of flow over a range of vertical scarp heights and various slopes for a range of wind velocities and for a variety of wind directions, and compare this to field observations. In general, flow separation occurs near the scarp base and over the scarp crest region, and jets commonly form at the scarp crest due to high topographically forced acceleration. Corkscrew vortices occur along the scarp base as wind flow becomes oblique. A general model of flow over scarps and various slopes and the relationships to echo dunes, climbing dunes and scarptop/clifftop dunes will also be presented.