Laboratory simulation of aeolian sand transport and physical modeling of flow around dunes

This paper discusses the possibilities of laboratory simulation of large-scale flow around dunes, both with and without saltation, and the study of physics of the small-scale particle motion occurring on a sand surface composed of like-moveable particles. Physics of the atmospheric boundary layer are presented in the context of laboratory applications. The governing equations of fluid and/or particle motion are discussed and analyzed for applications in laboratory testing. The most important similitude parameters, as applied to wind-tunnel requirements for conservation of mass, momentum, energy, and the boundary conditions are presented and discussed. Key findings and results are that: i) in general, flow around a dune or multiple dunes with saltation present cannot be accurately simulated in wind tunnels; ii) flow field around all or part of a full-scale dune can be simulated marginally in a wind tunnel, provided ''large'' model scales and ''reasonably high'' wind-tunnel speeds are used (the conditions of ''large'' model scales and ''reasonably high'' speeds are specified within the text); and, iii) it is possible to accurately replicate the process of saltation in wind tunnels provided appropriate similitude and independence criteria of Reynolds and Froude numbers are observed. Limited laboratory and wind-tunnel studies are cited.