| 1079 | | {{{#!td style="vertical-align:top;width: 150px" |
| 1080 | | [=#adjust_mixing_length '''adjust_mixing_length'''] |
| 1081 | | }}} |
| 1082 | | {{{#!td style="vertical-align:top;width: 50px" |
| 1083 | | L |
| 1084 | | }}} |
| 1085 | | {{{#!td style="vertical-align:top;width: 75px" |
| 1086 | | .F. |
| 1087 | | }}} |
| 1088 | | {{{#!td |
| 1089 | | Near-surface adjustment of the mixing length to the Prandtl-layer law.\\\\ |
| 1090 | | Usually the mixing length in LES models l,,LES,, depends (as in PALM) on the grid size and is possibly restricted further in case of stable stratification and near the lower wall (see parameter [#wall_adjustment wall_adjustment]). With '''adjust_mixing_length''' = ''.T.'' the Prandtl' mixing length l,,PR,, = kappa * z/phi is calculated and the mixing length actually used in the model is set l = MIN (l,,LES,, , l,,PR,,). This usually gives a decrease of the mixing length at the bottom boundary and considers the fact that eddy sizes decrease in the vicinity of the wall.\\\\ |
| 1091 | | '''Warning:''' So far, there is no good experience with '''adjust_mixing_length''' = ''.T.''{{{!}}}\\\\ |
| 1092 | | With '''adjust_mixing_length''' = ''.T.'' and the Prandtl-layer being switched on (see [#prandtl_layer prandtl_layer]) '' '(u*){{{**}}} 2+neumann' '' should always be set as the lower boundary condition for the TKE (see [#bc_e_b bc_e_b]), otherwise the near-surface value of the TKE is not in agreement with the Prandtl-layer law (Prandtl-layer law and Prandtl-Kolmogorov-Ansatz should provide the same value for K,,m,,). A warning is given, if this is not the case. |
| 1093 | | }}} |
| 1094 | | |---------------- |
