The Accumulator subnode is available from the context menu (right-click the
Collisions parent node) or from the
Physics toolbar,
Attributes menu. Each
Accumulator subnode defines a variable, called the accumulated variable, in the domains where the parent
Collisions node is applied. Whenever a particle collides with a background gas molecule, the value of the accumulated variable in that element is incremented based on the value of the user-defined
Source term
R for the particle.
Enter the Accumulated variable name. The default is
rpc. The accumulated variable is defined as
<scope>.<name>, where
<scope> includes the name of the physics interface node, parent
Collisions node, and the
Accumulator node; and
<name> is the accumulated variable name.
For example, if the Accumulator subnode is added to a
Collisions node in an instance of the Charged Particle Tracing interface using the default variable name
rpc, the accumulated variable name might be
cpt.col1.clacc1.rpc.
Select an option from the Collision types to accumulate list. The default is
All, or you could select any other subnode to the parent
Collisions node from the list. Change this setting, for example, if you only want to compute the number density of elastic collisions while ignoring charge exchange reactions.
Enter a Source R. The unit of the source term depends on the settings in the
Units section. Whenever a collision occurs, the accumulated variable is incremented by the source term in the mesh element the particle occupies. If the
Accumulator type is set to
Density, the source term is divided by the volume of the element (in 3D) or area of the element (in 2D).
Select a Dependent variable quantity from the list; the default is
Dimensionless [1]. To enter a unit, select
None from the list and in the
Unit field enter a value, for example,
K,
m/s, or
mol/m^3.