A Numerical Computation of Air Flow over a Sudden Change of Surface Roughness
| Autor: | C. C. Shir |
|---|---|
| Rok vydání: | 1972 |
| Předmět: | |
| Zdroj: | Journal of the Atmospheric Sciences. 29:304-310 |
| ISSN: | 1520-0469 0022-4928 |
| DOI: | 10.1175/1520-0469(1972)029<0304:ancoaf>2.0.co;2 |
| Popis: | This paper deals with a numerical study of the influence of changes in surface roughness on the turbulent boundary layer in the lower layer of the atmosphere under neutral conditions. The whole set of equations governing the flow is solved by a finite-difference method. The turbulent energy equation is included to provide a better understanding of turbulent mechanisms. The pressure gradient is treated implicitly. Computational results agree well with Bradley's observations. A local minimum of surface stress is found at a short distance from the edge (dividing line) in the case of smooth-to-rough transition. Two boundary layers, a velocity layer and a stress layer, are found. The height of the velocity layer is about one-half that of the stress layer. Both layers follow the 4/5 power law. The height-to-fetch ratio for the internal boundary layer is found to be about 1/10 for the stress and 1/20 for the velocity. The height-to-fetch ratio for a new nearly equilibrium layer is about 1/100 for the sm... |
| Databáze: | OpenAIRE |
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