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On the effective roughness length for use in numerical three-dimensional models

✍ Scribed by Jean-Claude André; Christian Blondin

Publisher
Springer
Year
1986
Tongue
English
Weight
796 KB
Volume
35
Category
Article
ISSN
0006-8314

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✦ Synopsis

We present analytical and numerical calculations of the effective roughness length (ERL) over a flat surface with varying roughness elements, for use in large-scale models. It is shown that ERL is mostly determined by the roughest elements present inside the averaging domain and that, more surprisingly, the ERL increases as the first level of the numerical model gets closer to the surface and its altitude approaches the value of the largest local roughness length. This effect further increases the drag coefficient, in addition to the well-known increase due to the lowering of the first model level.

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