Charge Accumulation Model Reference

You use the Charge Accumulation Model to account for charge accumulation when calculating the charged species dynamics at interfaces between dielectric surfaces and the gas/plasma.

When dielectric surfaces are exposed to a flow of ions and/or electrons, an accumulation of charge occurs on the surface, which causes discontinuity for the electric field across that interface. You use the Charge Accumulation Model to keep track of charged particle accumulation and to compute accumulated charge on the dielectric surfaces.

Table 1. Charge Accumulation Model Reference
Theory	See Cold, Non-Thermal Plasma.
Provided By	[physics continuum] > Models > Optional Models
Example Node Path	Continua > Physics 1 > Models > Charge Accumulation Model
Requires	For the Surface Charge Accumulation Settings to become active at an interface, the Charge Accumulation Model must be selected in both the fluid and solid physics continua on each side of the interface. The Charge Accumulation Model requires a double precision version of Simcenter STAR-CCM+.
	For fluid physics continua: Space: Any Material: Gas, Multi-Component Gas, Liquid, or Multi-Component Liquid. Time: Implicit Unsteady and then: When the accumulated charge is due to electrons only: Optional Models: Plasma (and auto-selected models) When the accumulated charge is due to ions only: Optional Models: Electrochemistry Electrochemistry: Electrochemical Species Optional Models: Electromagnetism Electromagnetism: Electrostatic Potential When the accumulated charge is due to electrons and ions, select models as if the accumulated charge is due to ions only, then also add: Optional Models: Plasma (and auto-selected models)		For solid physics continua: Space: Any Material: Solid Time: Implicit Unsteady Optional Models: Electromagnetism Electromagnetism: Electrostatic Potential
Activates	Interface Inputs	`Surface Charge Accumulation` See Interface Settings.
	Field Functions	Accumulated Surface Charge Density, Boundary Electron Number Accumulation, Boundary Molar Accumulation of [ion]. See Field Functions.

Interface Settings

Surface Charge Accumulation


Option	Corresponding Node Changes
Active Charge accumulation of electrons and/or ions (depending on model selection) is considered when the charged species dynamics is calculated in the plasma region next to the interface.	Under the [fluid region] > Boundaries > [interface boundary] > Physics Conditions node, for the following nodes, Method is set to Charge Accumulation—and cannot be changed: Electron Number Density Specification Electron Thermal Specification Wall Electrochemical Species Option
None No charge accumulation is accounted for when the charged species dynamics is calculated in the plasma region next to the interface.

Field Functions

Accumulated Surface Charge Density: Surface charge density accumulation on a charge accumulation interface. [C/m²]
Boundary Electron Number Accumulation: Surface electron number density accumulation on a charge accumulation interface. [/m²]
Boundary Molar Accumulation of [ion]: Surface electrochemical species molar density accumulation on a charge accumulation interface. [kmol/m²]