Changeset 11537 for NEMO/trunk/doc/latex/NEMO/subfiles/chap_time_domain.tex
- Timestamp:
- 2019-09-12T10:24:48+02:00 (5 years ago)
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NEMO/trunk/doc/latex/NEMO/subfiles/chap_time_domain.tex
r11435 r11537 86 86 where the subscript $F$ denotes filtered values and $\gamma$ is the Asselin coefficient. 87 87 $\gamma$ is initialized as \np{rn\_atfp} (namelist parameter). 88 Its default value is \np{rn\_atfp}\forcode{ =10.e-3} (see \autoref{sec:STP_mLF}),88 Its default value is \np{rn\_atfp}\forcode{=10.e-3} (see \autoref{sec:STP_mLF}), 89 89 causing only a weak dissipation of high frequency motions (\citep{farge-coulombier_phd87}). 90 90 The addition of a time filter degrades the accuracy of the calculation from second to first order. … … 172 172 173 173 The leapfrog environment supports a centred in time computation of the surface pressure, \ie\ evaluated 174 at \textit{now} time step. This refers to as the explicit free surface case in the code (\np{ln\_dynspg\_exp}\forcode{ =.true.}).174 at \textit{now} time step. This refers to as the explicit free surface case in the code (\np{ln\_dynspg\_exp}\forcode{=.true.}). 175 175 This choice however imposes a strong constraint on the time step which should be small enough to resolve the propagation 176 176 of external gravity waves. As a matter of fact, one rather use in a realistic setup, a split-explicit free surface 177 (\np{ln\_dynspg\_ts}\forcode{ =.true.}) in which barotropic and baroclinic dynamical equations are solved separately with ad-hoc177 (\np{ln\_dynspg\_ts}\forcode{=.true.}) in which barotropic and baroclinic dynamical equations are solved separately with ad-hoc 178 178 time steps. The use of the time-splitting (in combination with non-linear free surface) imposes some constraints on the design of 179 179 the overall flowchart, in particular to ensure exact tracer conservation (see \autoref{fig:TimeStep_flowchart}).
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