Statistics of Scalar Fields in the Atmospheric Boundary Layer Based on Large-Eddy Simulations. Part II: Forced Convection |
| |
| Authors: | Zbigniew Sorbjan |
| |
| Institution: | (1) Department of Physics, Marquette University, Wehr Phys. Bld., Room 377, 540 North 15th Street, Milwaukee, WI 53201-1881, USA |
| |
| Abstract: | Forced convection in a quasi-steady atmospheric boundary layer is investigated based on a large-eddy simulation (LES) model.
The performed simulations show that in the upper portion of the mixed layer the dimensionless (in terms of mixed layer scales)
vertical gradients of temperature, humidity, and wind velocity depend on the dimensionless height z/z
i
and the Reech number Rn. The peak values of variances and covariances at the top of the mixed layer, scaled in terms of the interfacial scales, are
functions of the interfacial Richardson number Ri. As a result expressions for the entrainment rates, in the case when the interfacial layer has a finite depth, and a condition
for the presence of moistening or drying regimes in the mixed layer, are derived. Profiles of dimensionless scalar moments
in the mixed layer are proposed to be expressed in terms of two empirical similarity functions F
m
and F
i
, dependent on dimensionless height z/z
i
, and the interfacial Richardson number Ri. The obtained similarity expressions adequately approximate the LES profiles of
scalar statistics, and properly represent the impact of stability, shear, and entrainment. They are also consistent with the
parameterization proposed for free convection in the first part of this paper. |
| |
| Keywords: | Atmospheric boundary layer Forced-convection Interfacial layer Entrainment Large-eddy simulations Similarity scales |
| 本文献已被 SpringerLink 等数据库收录！ |
|
