Changes between Version 39 and Version 40 of doc/app/particle_parameters

Timestamp:

Sep 13, 2010 1:00:17 PM (14 years ago)

Author:

suehring

Comment:

--

doc/app/particle_parameters

@@ -86 +86 @@
 By default, particles are absorbed at the top boundary. Alternatively, a reflection condition can be set by '''bc_par_t''' = '' 'reflect' ''.
 }}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#density_ratio '''density_ratio''']
+}}}
+{{{#!td style="vertical-align:top"
+0.0, 9 * 9999999.9
+}}}
+{{{#!td style="vertical-align:top"
+cyclic
+}}}
+{{{#!td
+Ratio of the density of the fluid and the density of the particles.
+
+With the default value the particles are weightless and transported passively with the resolved scale flow. In case of density_ratio /= 0.0 particles have a mass and hence inertia so that their velocity deviates more or less from the velocity of the surrounding flow. Particle velocity is calculated analytically and depends on (besides the density ratio and the current velocity difference between particles and surrounding fluid) the particle radius which is determined via radius as well as on the molecular viscosity (assumed as 1.461E-5 m2/s).
+
+If density_ratio = 1.0, the particle density corresponds to the density of the surrounding fluid and the particles do not feel any buoyancy. Otherwise, particles will be accelerated upwards (density_ratio > 1.0) or downwards (density_ratio < 1.0).
+
+With several groups of particles (see 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, 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.
+}}}
 Table row with nesting:\\
 {{{#!td style="vertical-align:top"