Changes between Version 175 and Version 176 of doc/app/initialization_parameters

Timestamp:

Aug 10, 2012 11:55:40 AM (12 years ago)

Author:

fricke

Comment:

--

doc/app/initialization_parameters

@@ -231 +231 @@
 Constant eddy diffusivities are used (laminar simulations).\\\\
 If this parameter is specified, both in the 1d and in the 3d-model constant values for the eddy diffusivities are used in space and time with K,,m,, = '''km_constant''' and K,,h,, = K,,m,, / [#prandtl_number prandtl_number]. The prognostic equation for the subgrid-scale TKE is switched off. Constant eddy diffusivities are only allowed with the Prandtl layer ([#prandtl_layer prandtl_layer]) switched off.
-}}}
-|----------------
-{{{#!td style="vertical-align:top"
-[=#km_damp_max '''km_damp_max''']
-}}}
-{{{#!td style="vertical-align:top"
-R
-}}}
-{{{#!td style="vertical-align:top"
-0.5*([#dx dx] or [#dy dy])
-}}}
-{{{#!td
-Maximum diffusivity used for filtering the velocity field in the vicinity of the outflow (in m^2^/s).\\\\
-When using non-cyclic lateral boundaries (see [#bc_lr bc_lr] or [#bc_ns bc_ns]), a smoothing has to be applied to the velocity field in the vicinity of the outflow in order to suppress any reflections of outgoing disturbances. Smoothing is done by increasing the eddy diffusivity along the horizontal direction which is perpendicular to the outflow boundary. Only velocity components parallel to the outflow boundary are filtered (e.g. v and w, if the outflow is along x). Damping is applied from the bottom to the top of the domain.\\\\
-The horizontal range of the smoothing is controlled by [#outflow_damping_width outflow_damping_width] which defines the number of gridpoints (counted from the outflow boundary) from where on the smoothing is applied. Starting from that point, the eddy diffusivity is linearly increased (from zero to its maximum value given by '''km_damp_max''') until half of the damping range width, from where it remains constant up to the outflow boundary. If at a certain grid point the eddy diffusivity calculated from the flow field is larger than as described above, it is used instead.\\\\
-The default value of '''km_damp_max''' has been empirically proven to be sufficient.
 }}}
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@@ -1162 +1146 @@
 '''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 multi-grid 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 u, to which a Neumann (zero gradient) condition is applied. At the outflow, a radiation condition is used for all velocity components, while a Neumann (zero gradient) condition is used for the scalars. For perturbation pressure Neumann (zero gradient) conditions are assumed both at the inflow and at the outflow.\\\\
-When using non-cyclic lateral boundaries, a filter is applied to the velocity field in the vicinity of the outflow in order to suppress any reflections of outgoing disturbances (see [#km_damp_max km_damp_max] and [#outflow_damping_width outflow_damping_width]).\\\\
 In order to maintain a turbulent state of the flow, it may be neccessary 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].\\\\
 In case of non-cyclic horizontal boundaries [#call_psolver_at_all_substeps call_psolver_at_all_substeps] = ''.T.'' should be used.\\\\
@@ -1442 +1425 @@
 Upper limit of the horizontal range for which random perturbations are to be imposed on the horizontal velocity field (gridpoints).\\\\
 If non-cyclic lateral boundary conditions are used (see [#bc_lr bc_lr] or [#bc_ns bc_ns]), this parameter gives the gridpoint number (counted horizontally from the inflow) up to which perturbations are imposed on the horizontal velocity field. Perturbations must be switched on with parameter [../d3par#create_disturbances create_disturbances].
-}}}
-|----------------
-{{{#!td style="vertical-align:top"
-[=#outflow_damping_width '''outflow_damping_width''']
-}}}
-{{{#!td style="vertical-align:top"
-I
-}}}
-{{{#!td style="vertical-align:top"
-MIN(20, [#nx nx]/2 or [#ny ny]/2)
-}}}
-{{{#!td
-Width of the damping range in the vicinity of the outflow (gridpoints).\\\\
-When using non-cyclic lateral boundaries (see [#bc_lr bc_lr] or [#bc_ns bc_ns]), a smoothing has to be applied to the velocity field in the vicinity of the outflow in order to suppress any reflections of outgoing disturbances. This parameter controlls the horizontal range to which the smoothing is applied. The range is given in gridpoints counted from the respective outflow boundary. For further details about the smoothing see parameter [#km_damp_max km_damp_max], which defines the magnitude of the damping.
 }}}
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