Defining Dynamic Domain Conditions

When a geometry Object is defined as Dynamic Domain, all material inside the Object will be active and any stationary material outside the Object will be excluded from any calculations, which improves simulation speed.  

A particle excluded from any calculation is called a frozen particle. If a frozen particle re-enters the dynamic domain then it is automatically included in the calculations again.

To use this feature, a geometry section, you must first define as a Dynamic Domain in the Creator. To do this, right- click the Geometries section, select Add Geometry and select Box. Rename the new geometry and set the Type to Dynamic Domain.

Since the Bulk Material will not physically interact with the Dynamic Domain Object, there is no option to assign material when dynamic domain has been selected.
Next, set the dimensions of the Dynamic Domain Object suitable for the simulation, any material inside the domain will be active and any outside may become frozen.

Frozen particles do not apply forces on geometry sections.

Frozen particles are excluded from Contact Detection, forces and velocities are not computed. 

Freezing Conditions

When Dynamic Domain is enabled, particles are frozen or unfrozen at the start of each Time Step according to the following flowchart:

Dynamic Domain Settings

Starting State

This option describes the initial particle state when the simulation is started:

• Unfreeze all Particles 
  This is the default behavior. All particles are initially unfrozen. 
• Freeze all Particles outside of Dynamic Domains 
  Particles not inside a Dynamic Domain geometry are frozen, all other particles are unfrozen. 
• Preserve current particle states 
  When continuing a paused simulation, restore the prior frozen state. Otherwise, particles are initially unfrozen. 

Particle Freeze Conditions 

As shown in the flowchart, the Check Conditions stage freezes a particle if that particle matches one or more of the enabled Particle Freeze conditions. 

• Basic Freeze Condition 
  This is the default freeze condition. It is recommended as a conservative option to only freeze particles that have definitely settled. Particles will only be frozen if they have moved less than the specified amount after the given number of checks. 
• Distance from dynamic domain is greater than ___  
  This will freeze particles as soon as they reach a certain distance away from the boundaries of the Dynamic Domain. 
• Particle velocity is slower than ___ 
  This will freeze particles as soon as their velocity drops below the given value. 

Maintain Frozen Contact History

This provides the option to discard contact history when a particle is frozen. If the contact history is not needed for analysis, this can be used to reduce the file size of the simulation.  
Dynamic Domain is based on the Method outlined in Mio et al., 2009.

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