Changes between Version 162 and Version 163 of doc/app/initialization_parameters

Timestamp:

Aug 8, 2011 8:35:38 AM (13 years ago)

Author:

maronga

Comment:

--

doc/app/initialization_parameters

@@ -199 +199 @@
 {{{#!td
 Application of a Galilei-transformation to the coordinate system of the model.\\\\
-With '''galilei_transformation''' = ''.T.,'' a so-called Galilei-transformation is switched on which ensures that the coordinate system of the model is moved along with the geostrophical wind. Alternatively, the model domain can be moved along with the averaged horizontal wind (see [#use_ug_for_galilei_tr use_ug_for_galilei_tr], this can and will naturally change in time). With this method, numerical inaccuracies of the Piascek - Williams - scheme (concerns in particular the momentum advection) are minimized. Beyond that, in the majority of cases the lower relative velocities in the moved system permit a larger time step ([#dt dt]). Switching the transformation on is only worthwhile if the geostrophical wind (ug, vg) and the averaged horizontal wind clearly deviate from the value 0. In each case, the distance the coordinate system has been moved is written to the file [../iofiles#RUN_CONTROL RUN_CONTROL].\\\\
+With '''galilei_transformation''' = ''.T.,'' a so-called Galilei-transformation is switched on which ensures that the coordinate system of the model is moved along with the geostrophical wind. Alternatively, the model domain can be moved along with the averaged horizontal wind (see [#use_ug_for_galilei_tr use_ug_for_galilei_tr], this can and will naturally change in time). With this method, numerical inaccuracies of the Piacsek - Williams - scheme (concerns in particular the momentum advection) are minimized. Beyond that, in the majority of cases the lower relative velocities in the moved system permit a larger time step ([#dt dt]). Switching the transformation on is only worthwhile if the geostrophical wind (ug, vg) and the averaged horizontal wind clearly deviate from the value 0. In each case, the distance the coordinate system has been moved is written to the file [../iofiles#RUN_CONTROL RUN_CONTROL].\\\\
 Non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]), the specification of a gestrophic wind that is not constant with height as well as e.g. stationary inhomogeneities at the bottom boundary do not allow the use of this transformation.
 }}}
@@ -765 +765 @@
 '''Important''': The number of ghost layers for 2d and 3d arrays changed. This affects also the user interface. Please adapt the allocation of 2d and 3d arrays in your user interface like [../userint/output#Allocate here]. Furthermore the exchange of ghost layers for 3d variables changed, so calls of exchange_horiz in the user interface have to be modified. Here an example for the u-component of the velocity: CALL exchange_horiz( u , nbgp ). \\\\
 '' 'pw-scheme' ''\\\\
-      The scheme of Piascek and Williams (1970, J. Comp. Phys., 6, 392-405) with central differences in the form C3 is used.
+      The scheme of Piacsek 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.\\\\
 '' '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 flow 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 of first order. For this reason the advection of scalar variables (see [#scalar_advec scalar_advec]) should then also be carried out with the upstream-spline scheme, because otherwise the scalar variables would be subject to large numerical diffusion due to the upstream scheme.\\\\
+      The upstream-spline scheme is used (see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piacsek-Williams scheme, this is characterized by much better numerical features (less numerical diffusion, better preservation of flow 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 of first order. For this reason the advection of scalar variables (see [#scalar_advec scalar_advec]) should then also be carried out with the upstream-spline scheme, because otherwise the scalar variables 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 neccessary for runs with stable stratification, even if this stratification appears only in parts of the model domain.\\\\
 With stable stratification the upstream-spline scheme also produces gravity waves with large amplitude, which must be suitably damped (see [../inipar#rayleigh_damping_factor rayleigh_damping_factor]).\\\\
@@ -961 +961 @@
 '''Important''': The number of ghost layers for 2d and 3d arrays changed. This affects also the user interface. Please adapt the allocation of 2d and 3d arrays in your user interface like [../userint/output#Allocate here]. Furthermore the exchange of ghost layers for 3d variables changed, so calls of exchange_horiz in the user interface have to be modified. Here an example for the potential temperature: CALL exchange_horiz( pt , nbgp ). \\\\
 '' 'pw-scheme' ''\\\\
-      The scheme of Piascek and Williams (1970, J. Comp. Phys., 6, 392-405) with central differences in the form C3 is used.
+      The scheme of Piacsek 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' ''\\\\
@@ -967 +967 @@
       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.\\\\
+      The upstream-spline-scheme is used (see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piacsek 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]).\\\\