Changes between Version 94 and Version 95 of doc/app/initialization_parameters

Timestamp:

Sep 15, 2010 12:02:58 PM (14 years ago)

Author:

kanani

Comment:

--

doc/app/initialization_parameters

@@ -965 +965 @@
 |----------------
 {{{#!td style="vertical-align:top"
-[=#<insert_parameter_name> '''<insert_parameter_name>''']
-}}}
-{{{#!td style="vertical-align:top"
-<insert type>
-}}}
-{{{#!td style="vertical-align:top"
-<insert value>
-}}}
-{{{#!td
-<insert explanation>
+[=#scalar_advec '''scalar_advec''']
+}}}
+{{{#!td style="vertical-align:top"
+C*10
+}}}
+{{{#!td style="vertical-align:top"
+'pw-scheme'
+}}}
+{{{#!td
+Advection scheme to be used for the scalar quantities.\\\\
+The user can choose between the following schemes:\\\\
+'' 'pw-scheme' ''\\\
+      The scheme of Piascek and Williams (1970, J. Comp. Phys., 6, 392-405) with central differences in the form C3 is used.
+      If intermediate Euler-timesteps are carried out in case of [#timestep_scheme timestep_scheme] = '' 'leapfrog+euler' '' the advection scheme is - for the Euler-timestep - automatically switched to an upstream-scheme.\\\\
+'' 'bc-scheme' ''\\\
+      The Bott scheme modified by Chlond (1994, Mon. Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with very small numerical diffusion and therefore very good conservation of scalar flow features. The scheme however, is computationally very expensive both because it is expensive itself and because it does (so far) not allow specific code optimizations (e.g. cache optimization). Choice of this scheme forces the Euler timestep scheme to be used for the scalar quantities. For output of horizontally averaged profiles of the resolved / total heat flux, [../d3par#data_output_pr data_output_pr] = '' 'w*pt*BC' '' / '' 'wptBC' '' should be used, instead of the standard profiles ('' 'w*pt*' '' and '' 'wpt' '') because these are too inaccurate with this scheme. However, for subdomain analysis (see [../d3par#statistic_regions statistic_regions]) exactly the reverse holds: here '' 'w*pt*BC' '' and '' 'wptBC' '' show very large errors and should not be used.\\\\
+      This scheme is not allowed for non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]).\\\\
+'' 'ups-scheme' ''\\\
+      The upstream-spline-scheme is used (see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek Williams scheme, this is characterized by much better numerical features (less numerical diffusion, better preservation of flux structures, e.g. vortices), but computationally it is much more expensive. In addition, the use of the Euler-timestep scheme is mandatory ([#timestep_scheme timestep_scheme] = '' 'euler' ''), i.e. the timestep accuracy is only first order. For this reason the advection of momentum (see [#momentum_advec momentum_advec]) should then also be carried out with the upstream-spline scheme, because otherwise the momentum would be subject to large numerical diffusion due to the upstream scheme.\\\\
+Since the cubic splines used tend to overshoot under certain circumstances, this effect must be adjusted by suitable filtering and smoothing (see [#long_filter_factor long_filter_factor]). This is always neccesssary for runs with stable stratification, even if this stratification appears only in parts of the model domain.\\\\
+With stable stratification the upstream-upline scheme also produces gravity waves with large amplitude, which must be suitably damped (see [#rayleigh_damping_factor rayleigh_damping_factor]).\\\\
+'''Important:'''\\
+The  upstream-spline scheme is not implemented for humidity and passive scalars (see [#humidity humidity] and [#passive_scalar passive_scalar]) and requires the use of a 2d-domain-decomposition. The last conditions severely restricts code optimization on several machines leading to very long execution times! This scheme is also not allowed for non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]).\\\\
+A differing advection scheme can be chosen for the subgrid-scale TKE using parameter [#use_upstream_for_tke use_upstream_for_tke].
 }}}
 |----------------