ESTIMATING SHEAR VELOCITY AND ROUGHNESS LENGTH FROM VELOCITY PROFILES

被引:57
|
作者
BERGERON, NE
ABRAHAMS, AD
机构
关键词
D O I
10.1029/92WR00897
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
In turbulent boundary layer flows, shear velocity u* and roughness length z0 are commonly derived from semilogarithmic flow velocity profiles by fitting a straight line by ordinary least squares regression to the profile and calculating estimates of u* and z0 from the slope and intercept of the computed regression equation. However, it is not clear from the literature whether the appropriate regression is of flow velocity u on the logarithm of height above the bed ln z or of ln z on u. In order to calculate estimates of u* and z0, the true or structural relation between u and ln z must be established. Because u is generally observed with much greater error than is ln z, the structural relation may be estimated by regressing u on ln z; regressing ln z on u is incorrect. An analysis of 24 stream channel flow velocity profiles indicates that even in situations where the correlation between u and ln z exceeds 0.9, performing the incorrect regression can result in the considerable overestimation of u* and z0.
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页码:2155 / 2158
页数:4
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