Nonlocal Accumulator
Use the Nonlocal Accumulator subnode to communicate information from a ray’s current position to the position from which it was released.
The subnode is available from the context menu (right-click the Inlet parent node) or from the Physics toolbar, Attributes menu.
Each Nonlocal accumulator subnode defines a variable, called the accumulated variable, that is computed using variables defined on rays released by the parent Inlet node or on domains and boundaries encountered by such rays.
Accumulator Settings
Select an Accumulator type: Density (default) or Count.
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For Density the accumulated variable is divided by the volume of the mesh element where it is defined.
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For Count the accumulated variable is unaffected by the element size.
Select an option from the Accumulate over list: Elements (default) or Elements and time.
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For Elements the accumulated variable is proportional to the instantaneous value of the Source term R for all applicable rays.
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For Elements and time the time derivative of the accumulated variable is proportional to the instantaneous value of the Source term R for all applicable rays, and thus the accumulated variable considers the time history of rays in the modeling domain instead of just their current values.
Enter the Accumulated variable name. The default is rpi.
Enter a Source R. The unit of the source depends on the settings in the Units section. The source term is used to calculate the accumulated variable in a manner specified by the Accumulate over and Accumulator type settings.
Select a Source geometric entity level: Domains, Boundaries, or Domains and boundaries.
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If Domains is selected, rays only contribute to the accumulated variable on their releasing surface if they are still active; that is, they are still propagating through a domain.
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If Boundaries is selected, the rays only contribute to the accumulated variable if they have become stuck or frozen to a boundary somewhere in the model.
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If Domains and boundaries is selected, all of the active, stuck, and frozen rays released by a feature can contribute to the accumulated variable.
Units
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.
Smoothing
Select the Compute smoothed accumulated variable check box to enter a Smoothing radius r (SI unit: m). The default is 0.1 m.