Abstract
We study the vorticity field induced by flow around surface mounted obstacles, focussing on the streamwise vorticity. A combination of analytical and numerical model results indicates that the mechanisms for the generation of the mean flow vorticity, as well as its form and magnitude, are not significantly influenced by turbulence, at least for a first-order turbulence closure. This result is in qualitative agreement with suggestions of previous studies. The numerical model is used to simulate flow around an asymmetric hill and, in terms of the shape and positioning of the trailing vortex, good agreement is found between the simulations and observations. However, the strength of the vortex appears to be significantly underestimated by the numerical model. The influence of the slope of the hill and of the angle of incidence of the mean wind on the trailing vorticity is also investigated. Finally, it is found that the occurrence of a dominant trailing vortex, at least one of the strength predicted by the numerical model, does not have a significant impact on the momentum budget of the downstream boundary layer.
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Hobson, J.M., Wood, N. Trailing Vortices In Flow Around Smoothly Shaped Obstacles. Boundary-Layer Meteorology 84, 427–466 (1997). https://doi.org/10.1023/A:1000401306058
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DOI: https://doi.org/10.1023/A:1000401306058