Similarity-Law Profiles in Thermally Stratified Shear Flows

摘要

Measured mean wind velocity and temperature profiles in the thermally stratified flow of a wind tunnel near the wall can be expressed in a log-plus-linear law which is also representative of the field data. Although both laboratory and field data show some scatter around the theoretical line, a similarity between the mean wind velocity and temperature profiles does seem to exist. The scatter can partially be attributed to the fact that in some cases the Monin-Obukhov length scale becomes comparable in magnitude to the height under consideration. This in turn breaks down the assumption that was made in order to obtain the law. Subsequently, log-plus-linear-plus-square profiles were tried and the results showed little improvement on the scatter. Free convection seems to prevail in some runs of both laboratory and field experiments. The transition from a forced convection to a free convection in the thermally stratified flow was shown to be gradual and occurred at a Richardson number in the same range as predicted. Both the laboratory and the field data for zeta