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initialization_parameters

Timestamp:: Sep 15, 2010 4:33:36 PM (14 years ago)
Author:: kanani
Comment:: --

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doc/app/initialization_parameters

-                      v113
+                      v114
 Number of processors along x-direction of the virtual processor net.\\\\
 For parallel runs, the total number of processors to be used is given by the '''mrun'''-option -X. By default, depending on the type of the parallel computer, PALM generates a 1d processor net (domain decomposition along x, [#npey npey] = ''1'') or a 2d-net (this is favored on machines with fast communication network and/or large number of processors (>256)). In case of a 2d-net, it is tried to make it more or less square-shaped. If, for example, 16 processors are assigned (-X 16), a 4 * 4 processor net is generated ('''npex''' = 4, '''npey''' = 4). This choice is optimal for square total domains ([#nx nx] = [#ny ny]), since then the number of ghost points at the lateral boundarys of the subdomains reaches a minimum. If nx and ny differ extremely, the processor net should be manually adjusted using adequate values for '''npex''' and '''npey'''.\\\\
 '''Important:'''\\\\
+'''Important:'''\\
 The value of '''npex''' * '''npey''' must exactly match the value assigned by the '''mrun'''-option -X. Otherwise the model run will abort with a corresponding error message.\\\\
 Additionally, the specification of '''npex''' and '''npey''' may of course override the default setting for the domain decomposition (1d or 2d) which may have a significant (negative) effect on the code performance.
 …
 {{{#!td
 Type of cycle to be used with the multi-grid method.\\\\
 This parameter determines which type of cycle is applied in the multi-grid method used for solving the Poisson equation for perturbation pressure (see [#psolver psolver]). It defines in which way it is switched between the fine and coarse grids. So-called v- and w-cycles are realized (i.e. '''cycle_m'''g may be assigned the values '' 'v' '' or '' 'w' ''). The computational cost of w-cycles is much higher than that of v-cycles, however, w-cycles give a much better convergence.
+This parameter determines which type of cycle is applied in the multi-grid method used for solving the Poisson equation for perturbation pressure (see [#psolver psolver]). It defines in which way it is switched between the fine and coarse grids. So-called v- and w-cycles are realized (i.e. '''cycle_mg''' may be assigned the values '' 'v' '' or '' 'w' ''). The computational cost of w-cycles is much higher than that of v-cycles, however, w-cycles give a much better convergence.
 }}}
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 …
       If [#mg_cycles mg_cycles] is set to its optimal value, the computing time of the multi-grid scheme amounts approximately to that of the direct solver '' 'poisfft','' as long as the number of grid points in the three directions of space corresponds to a power-of-two (2^n^) where ''n'' >= 5 must hold. With large ''n'', the multi-grid scheme can even be faster than the direct solver (although its accuracy is several orders of magnitude worse, but this does not affect the accuracy of the simulation). Nevertheless, the user should always carry out some test runs in order to find out the optimum value for [#mg_cycles mg_cycles], because the CPU time of a run very critically depends on this parameter.\\\\
       This scheme requires that the number of grid points of the subdomains (or of the total domain, if only one PE is uesd) along each of the directions can at least be devided once by 2 without rest.\\\\
 With parallel runs, starting from a certain grid level the data of the subdomains are possibly gathered on PE0 in order to allow for a further coarsening of the grid. The grid level for gathering can be manually set by [#mg_switch_to_pe0_level mg_switch_to_pe0_level].\\\\
       Using this procedure requires the subdomains to be of identical size (see [#grid_matching grid_matching]).\\\\
+With parallel runs, starting from a certain grid level the data of the subdomains are possibly gathered on PE0 in order to allow for a further coarsening of the grid. The grid level for gathering can be manually set by [#mg_switch_to_pe0_level mg_switch_to_pe0_level].\\
+Using this procedure requires the subdomains to be of identical size (see [#grid_matching grid_matching]).\\\\
 '' 'sor' ''\\\\
       Successive over relaxation method (SOR). The convergence of this iterative scheme is steered with the parameters [#omega_sor omega_sor], [#nsor_ini nsor_ini] and [#nsor nsor].\\
 …
 }}}
 {{{#!td style="vertical-align:top"
+/3 *\\
+zu(nz)\\\
+(ocean: 2/3*\\
+zu(0))
+/3*zu(nz)\\
+(ocean:\\
+/3*zu(0))
 }}}
 {{{#!td
 …
 }}}
 {{{#!td
 Angular velocity of the rotating system (in rad s^-1^).\\\\
+Angular velocity of the rotating system (in rad/s).\\\\
 The angular velocity of the earth is set by default. The values of the Coriolis parameters are calculated as:\\\\
       f = 2.0 * '''omega''' * sin([#phi phi])\\
 …
 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 [../d3par#call_psolver_at_all_substeps call_psolver_at_all_substeps] = ''.T.'' should be used.
+'''Note:'''
+In case of non-cyclic horizontal boundaries [../d3par#call_psolver_at_all_substeps call_psolver_at_all_substeps] = ''.T.'' should be used.\\\\
+'''Note:'''\\
 Using non-cyclic lateral boundaries requires very sensitive adjustments of the inflow (vertical profiles) and the bottom boundary conditions, e.g. a surface heating should not be applied near the inflow boundary because this may significantly disturb the inflow. Please check the model results very carefully.
 }}}
 …
 }}}
 {{{#!td style="vertical-align:top"
 MIN(10, nx/2 or ny/2)
+MIN(10, [#nx nx]/2 or [#ny ny]/2)
 }}}
 {{{#!td
 …
 }}}
 {{{#!td style="vertical-align:top"
 MIN(100, 3/4*nx or 3/4*ny)
+MIN(100, 3/4*[#nx nx] or 3/4*[#ny ny])
 }}}
 {{{#!td
 …
 Currently, '''canyon_wall_south''' must be at least 1 * [#dy dy] and less than ( [#ny ny]  - 1 ) * dy -  [#canyon_width_y canyon_width_y]. This parameter requires [#topography topography] = '' 'single_street_canyon'.''\\\\
 The default value '''canyon_wall_south''' = ( ( ny + 1 ) * dy -  canyon_width_y ) / 2 centers the canyon in y-direction.
-}}}
-|----------------
-{{{#!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>
 }}}
 |----------------
 …
 This parameter applies only in case of a non-flat topography and [#passive_scalar passive_scalar] = ''.T.''.
 }}}
+|----------------
+{{{#!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>
+}}}
+|----------------
+{{{#!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>
+}}}
 [[BR]]
 …
 If [#plant_canopy plant_canopy] is set ''.T.'', the user can prescribe a heat flux at the top of the plant canopy.
 It is assumed that solar radiation penetrates the canopy and warms the foliage which, in turn, warms the air in contact with it.\\\\
+'''Note:''' Instead of using the value prescribed by [#surface_heatflux surface_heatflux], the near surface heat flux is determined from an exponential function that is dependent on the cumulative leaf_area_index (Shaw and Schumann (1992, Boundary Layer Meteorol., '''61''', 47-64)).
+'''Note:'''\\
+Instead of using the value prescribed by [#surface_heatflux surface_heatflux], the near surface heat flux is determined from an exponential function that is dependent on the cumulative leaf_area_index (Shaw and Schumann (1992, Boundary Layer Meteorol., 61, 47-64)).
 }}}
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