Changes between Version 40 and Version 41 of doc/app/particle_parameters
- Timestamp:
- Sep 13, 2010 1:04:05 PM (14 years ago)
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doc/app/particle_parameters
v40 v41 97 97 }}} 98 98 {{{#!td 99 Ratio of the density of the fluid and the density of the particles. 99 Ratio of the density of the fluid and the density of the particles. \\ 100 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 radius] as well as on the molecular viscosity (assumed as 1.461E-5 m{{{^2}}}/s). 100 101 101 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).102 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''). 102 103 103 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). 104 105 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. 104 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''. 106 105 }}} 107 106 Table row with nesting:\\