Changes between Version 481 and Version 482 of doc/app/initialization_parameters

Timestamp:

Jan 18, 2021 10:57:42 AM (4 years ago)

Author:

raasch

Comment:

--

doc/app/initialization_parameters

@@ -1454 +1454 @@
 By default, a cyclic boundary condition is used along x.\\\\
 '''bc_lr''' may also be assigned the values '' 'dirichlet/radiation' '' (inflow from left, outflow to the right) or '' 'radiation/dirichlet' '' (inflow from right, outflow to the left). This requires the multigrid method to be used for solving the Poisson equation for perturbation pressure (see [#psolver psolver]) and it also requires cyclic boundary conditions along y (see [#bc_ns bc_ns]).\\\\
-In case of these non-cyclic lateral boundaries, a Dirichlet condition is used at the inflow for all quantities (initial vertical profiles - see [#initializing_actions initializing_actions] - are fixed during the run) except e, to which a Neumann (zero gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components and the calculation method of the required phase velocity is controlled by the parameter [#use_cmax use_cmax].
+In case of these non-cyclic lateral boundaries, a Dirichlet condition is used at the inflow for all quantities (initial vertical profiles - see [#initializing_actions initializing_actions] - are fixed during the run) except e, to which a Neumann (zero gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components. A constant phase velocity is used, which is set to the maximum velocity allowed by the CFL criterion (i.e. for a Courant number of one).
 For scalars, a Neumann condition is used. For the perturbation pressure, Neumann conditions are assumed both at the inflow and at the outflow.\\\\
 In order to maintain a turbulent state of the flow, it may be necessary to continuously impose perturbations on the horizontal velocity field in the vicinity of the inflow throughout the whole run. This can be switched on using [../d3par#create_disturbances create_disturbances]. The horizontal range to which these perturbations are applied is controlled by the parameters [#inflow_disturbance_begin inflow_disturbance_begin] and [#inflow_disturbance_end inflow_disturbance_end]. The vertical range and the perturbation amplitude are given by [../d3par#disturbance_level_b disturbance_level_b], [../d3par#disturbance_level_t disturbance_level_t], and [../d3par#disturbance_amplitude disturbance_amplitude]. The time interval at which perturbations are to be imposed is set by [../d3par#dt_disturb dt_disturb]. Note that these inflow perturbances are added '''in addition''' to the standard perturbances that are activated with [../d3par#create_disturbances create_disturbances]. The standard perturbances can be deactivated by setting the d3par-parameter [../d3par#disturbance_energy_limit disturbance_energy_limit] = 0.0 .\\\\
@@ -1486 +1486 @@
 '''bc_ns''' may also be assigned the values '' 'dirichlet/radiation' '' (inflow from rear ("north"), outflow to the front ("south")) or '' 'radiation/dirichlet' '' (inflow from front ("south"), outflow to the rear ("north")). This requires the multigrid method to be used for solving the Poisson equation for perturbation pressure (see [#psolver psolver]) and it also requires cyclic boundary conditions along x (see
 [#bc_lr bc_lr]).\\\\
-In case of these non-cyclic lateral boundaries, a Dirichlet condition is used at the inflow for all quantities (initial vertical profiles - see [#initializing_actions initializing_actions] - are fixed during the run) except e, to which a Neumann (zero gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components and the calculation method of the required phase velocity is controlled by the parameter [#use_cmax use_cmax].
+In case of these non-cyclic lateral boundaries, a Dirichlet condition is used at the inflow for all quantities (initial vertical profiles - see [#initializing_actions initializing_actions] - are fixed during the run) except e, to which a Neumann (zero gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components. A constant phase velocity is used, which is set to the maximum velocity allowed by the CFL criterion (i.e. for a Courant number of one).
 For scalars, a Neumann (zero gradient) condition is used. For the perturbation pressure, Neumann (zero gradient) conditions are assumed both at the inflow and at the outflow.\\\\
 In case of nested run, except if [#nesting_mode nesting_mode]='' 'vertical' '', the default value of '' 'bc_lr' '' in the nest domains is not '' 'cyclic' '' but '' 'nested' '' instead. For the root domain of a nested run the default is '' 'cyclic' '' as usually.\\
@@ -1977 +1977 @@
 For using this outflow method [#bc_lr bc_lr] = '' 'dirichlet/radiation' '' is required. This method can only be used for an outflow boundary at the right model boundary, so far.\\\\
 The vertical source plane from where to copy the values of u, v, w, pt, q, s, and e should be placed not too close to the outflow boundary.
-}}}
-|----------------
-{{{#!td style="vertical-align:top"
-[=#use_cmax '''use_cmax''']
-}}}
-{{{#!td style="vertical-align:top"
-L
-}}}
-{{{#!td style="vertical-align:top"
-.T.
-}}}
-{{{#!td
-Parameter to choose the calculation method of the phase velocity at the outflow boundary in case of non-cyclic lateral boundary conditions.
-
-In case of non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]), radiation boundary conditions are used for the velocity components at the outflow boundary.
-If [#use_cmax use_cmax] = ''.T.'', the phase velocity is set to the maximum value that ensures numerical stability (CFL-condition). With this method, the radiation boundary conditions are simplified, as phase velocity must not be calculated.
-
-Setting [#use_cmax use_cmax] = ''.F.'', the phase velocity is calculated after every time step, using the approach of Orlanski (1976). Additionally, local phase velocities are averaged along the outflow boundary in each height level.
-
-Detailed information can be found in the documentation of the [../../tec/noncyclic non-cyclic lateral boundary conditions].
 }}}
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