Changeset 5960 for branches/2015/dev_MetOffice_merge_2015/DOC
- Timestamp:
- 2015-12-01T11:31:27+01:00 (9 years ago)
- Location:
- branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles
- Files:
-
- 2 edited
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branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Chapters/Chap_DIA.tex
- Property svn:keywords set to Id
r5515 r5960 1522 1522 \\ 1523 1523 1524 \section{Courant numbers} 1525 Courant numbers provide a theoretical indication of the model's numerical stability. The advective Courant numbers can be calculated according to 1526 \begin{equation} 1527 \label{eq:CFL} 1528 C_u = |u|\frac{\rdt}{e_{1u}}, \quad C_v = |v|\frac{\rdt}{e_{2v}}, \quad C_w = |w|\frac{\rdt}{e_{3w}} 1529 \end{equation} 1530 in the zonal, meridional and vertical directions respectively. The vertical component is included although it is not strictly valid as the vertical velocity is calculated from the continuity equation rather than as a prognostic variable. Physically this represents the rate at which information is propogated across a grid cell. Values greater than 1 indicate that information is propagated across more than one grid cell in a single time step. 1531 1532 The variables can be activated by setting the \np{nn\_diacfl} namelist parameter to 1 in the \ngn{namctl} namelist. The diagnostics will be written out to an ascii file named cfl\_diagnostics.ascii. In this file the maximum value of $C_u$, $C_v$, and $C_w$ are printed at each timestep along with the coordinates of where the maximum value occurs. At the end of the model run the maximum value of $C_u$, $C_v$, and $C_w$ for the whole model run is printed along with the coordinates of each. The maximum values from the run are also copied to the ocean.output file. 1524 1533 1525 1534 -
branches/2015/dev_MetOffice_merge_2015/DOC/TexFiles/Namelist/namctl
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r4147 r5960 13 13 ! (no physical validity of the results) 14 14 nn_timing = 0 ! timing by routine activated (=1) creates timing.output file, or not (=0) 15 nn_diacfl = 0 ! Write out cfl diagnostics (=1) in cfl_diagnostics.ascii, or not (=0) 15 16 /
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