Changes between Version 118 and Version 119 of doc/app/particle_parameters

Timestamp:

Feb 21, 2012 11:09:10 AM (13 years ago)

Author:

raasch

Comment:

--

doc/app/particle_parameters

@@ -106 +106 @@
       Collision kernel from Hall (1980, J. Atmos. Sci., 2486-2507), which considers collision due to pure gravitational effects. Larger droplets have a higher terminal fall velocity and are collecting smaller ones. Only terminal droplet velocities are considered in this kernel (not their effective velocities).
 
+'' 'hall_fast' ''
+      Same as '' 'hall' '', but a collision efficiency table is calculated only once (at the beginning of the simulation) for fixed radius classes in the range [1.0E-6,2.0E-4] m. The number of classes to be used (i.e. the resolution of the kernel) can be set by parameter [#radius_classes radius_classes]. This method significantly reduces the total cpu-time for a job.
+
 '' 'none' ''
       Droplet collision is switched off.
@@ -115 +118 @@
       Beside gravitational effects (treated with the Hall-kernel) also the effects of turbulence on the collision are considered using parameterizations of Ayala et al. (2008, New J. Phys., 10, 075015) and Wang and Grabowski (2009, Atmos. Sci. Lett., 10, 1-8). This kernel includes three possible effects of turbulence: the modification of the relative velocity between the droplets, the effect of preferential concentration, and the enhancement of collision efficiencies.
 
+'' 'wang_fast' ''
+      Same as '' 'wang' '', but a collision efficiency table is calculated only once (at the beginning of the simulation) for fixed radius- and dissipation classes in the ranges [1.0E-6,2.0E-4] m, and [0.0,1000.0] cm**2/s**3 respectively. The number of classes to be used (i.e. the resolution of the kernel) can be set by parameters [#radius_classes radius_classes], and [#dissipation_classes dissipation_classes]. This method significantly reduces the total cpu-time for a job.
+
 '''Attention:''' Switching on the collision process drastically increases the CPU time of jobs.
 }}}
@@ -135 +141 @@
 
 With several groups of particles (see [#number_of_particle_groups number_of_particle_groups]), each group can be assigned a different value. If the number of values given for '''density_ratio''' is less than the number of groups defined by [#number_of_particle_groups number_of_particle_groups]), then the last assigned value is used for all remaining groups. This means that by default the particle density ratio for all groups will be ''0.0''.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#dissipation_classes '''dissipation_classes''']
+}}}
+{{{#!td style="vertical-align:top"
+I
+}}}
+{{{#!td style="vertical-align:top"
+20
+}}}
+{{{#!td
+Number of dissipation classes to be used in the collision efficiency table.\\
+This parameter comes into effect, if parameter [#collision_kernel collision_kernel] is set to '' 'wang_fast' ''. It defines the number of dissipation classes which spawn the collision efficiency table. The interval [1.0,1000.0] cm**2/s**3 is divided into n (= '''dissipation_classes''') equidistant parts. 
 }}}
 |----------------
@@ -510 +530 @@
 |----------------
 {{{#!td style="vertical-align:top"
+[=#radius_classes '''radius_classes''']
+}}}
+{{{#!td style="vertical-align:top"
+I
+}}}
+{{{#!td style="vertical-align:top"
+20
+}}}
+{{{#!td
+Number of radius classes to be used in the collision efficiency table.\\
+This parameter comes into effect, if parameter [#collision_kernel collision_kernel] is set to '' 'hall_fast' '' or '' 'wang_fast' ''. It defines the number of radius classes which spawn the collision efficiency table. The interval [1.0E-6,2.0E-4] m is divided into n (= '''radius_classes''') logarithmic equidistant parts. 
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
 [=#random_start_position '''random_start_position''']
 }}}