Nonisothermal Plasma Flow
Use the Nonisothermal Plasma Flow () multiphysics coupling node to simulate the coupling between plasma, fluid flow and heat transfer. Specifically, it combines the Plasma, Heat Transfer in Fluids, and Laminar Flow interfaces.
It defines u, T, and p variables in order to set the Velocity field, Temperature, and Absolute pressure in the Model Inputs section of the Plasma Model feature in the Plasma interface, as well as in the Model Input section of the Fluid Properties feature in the Laminar Flow interface, and in the Model Input section of the Fluid feature in the Heat Transfer in Fluids interface.
It also synchronizes the definition of the reference temperature between Heat Transfer and Fluid Flow interfaces, and the definition of density can be synchronized from the Plasma interface to the other two interfaces.
In addition, it gets several fluid dynamics properties as well as thermodynamics properties from the Plasma interface and provides these quantities to the corresponding Heat Transfer and Fluid Flow interfaces (for example, thermal conductivity, dynamic viscosity, heat capacity, and so on).
The Nonisothermal Plasma Flow multiphysics coupling node is designed based on the Nonisothermal Flow multiphysics coupling node, and the couplings between the Plasma interface with the Fluid Flow and Heat Transfer interfaces are introduced. Therefore, Nonisothermal Plasma Flow should not be combined with the Nonisothermal Flow multiphysics coupling node, as unwanted conflicts and duplicates could be induced.
Settings
The Label is the default multiphysics coupling feature name.
The Name is used primarily as a scope prefix for variables defined by the coupling node. Refer to such variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different coupling nodes or physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first multiphysics coupling feature in the model) is nipf1.
Domain Selection
The Nonisothermal Plasma Flow coupling node selection is locked to the Selection of the coupled Plasma interface.
Coupled Interfaces
This section defines the physics involved in the multiphysics coupling. The Plasma, Fluid flow and Heat transfer lists include all applicable physics interfaces.
The default values depend on how this coupling node is created:
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If it is added from the Physics ribbon (Windows users), Physics contextual toolbar (Mac and Linux users), or context menu (all users), then the first physics interface of each type in the component is selected as the default.
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If it is added automatically when a multiphysics interface is chosen in the Model Wizard or Add Physics window, then the two participating physics interfaces are selected.
You can also select None from either list to uncouple the node from a physics interface. If the physics interface is removed from the Model Builder, for example Heat Transfer in Fluids is deleted, then the Heat transfer list defaults to None as there is nothing to couple to.
Material Properties
Reference Temperature
Select an option from the Specify reference temperature list — From heat transfer interface (the default), From fluid flow interface, or User defined.
For From heat transfer interface, set the Reference temperature Tref (SI unit: K) in the Physical Model section of the interface selected in the Heat transfer list of the Coupled Interfaces section. The Reference temperature input in the Fluid flow interface is synchronized to the same value or expression, and is not editable.
For From fluid flow interface, set the Reference temperature Tref (SI unit: K) in the Physical Model section of the interface selected in the Fluid flow list of the Coupled Interfaces section. The Reference temperature input in the Heat transfer interface is synchronized to the same value or expression, and is not editable.
For User defined, set a value or expression. The Reference temperature inputs in the Physical Model sections of the Heat transfer and Fluid flow interfaces are synchronized to the same value or expression, and are not editable.
Density
Select an option from the Specify density list: From plasma interface (the default), or User defined:
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For From plasma interface: the Density is defined in the Density section of the Plasma Model node, in the plasma coupled interface. The density value is defined either using ideal gas law if Ideal gas is selected, or using manually entered value if Mixture density is selected. The same value is automatically set in the Fluid Properties section of the Fluid Properties node, in the Fluid Flow coupled interface, and is also set in the Thermodynamics, Fluid section of the Fluid node, in the Heat Transfer coupled interface.
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For User defined, enter a Density ρ (SI unit: kg/m3). The same value is automatically set in the Fluid Properties section of the Fluid Properties node, in the Fluid Flow coupled interface, and in the Thermodynamics, Fluid section of the Fluid node, in the Heat Transfer coupled interface.
The density definition in the Nonisothermal Plasma Flow node ensures that the same definition of the density is used on the plasma, fluid flow and heat transfer interfaces.
Fluid Flow and Heat Transfer Properties
Some fluid dynamics properties and thermodynamics properties can be defined in this section, including thermal conductivity, dynamic viscosity, heat capacity at constant pressure, specific gas constant, mean molar mass, and ratio of specific heats. For each of these properties, a selectable list can be selected to either specify the property From plasma interface where the value is calculated in the Plasma coupled interface, or from User defined where the value is manually entered, except for ratio of specific heats where the value can only be manually entered.
The value of these properties is automatically set in the Fluid Flow coupled interface and in the Heat Transfer coupled interface:
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The thermal conductivity is set in the Heat Conduction, Fluid section of the Fluid node, in the Heat Transfer coupled interface.
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The dynamic viscosity is set in the Fluid Properties section of the Fluid Properties node, in the Fluid Flow coupled interface.
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The heat capacity at constant pressure, specific gas constant, mean molar mass, and ratio of specific heats are set in the Thermodynamics, Fluid section of the Fluid node, in the Heat Transfer coupled interface. The Fluid type should be selected as either Ideal gas or Gas/Liquid, and the proper thermodynamics properties will be supplied.
Heat Sources
The Include heat source checkbox is selected by default to account for the heat source corresponding to plasma heating. The Specify volume heat source can be either From plasma interface where the value is calculated in the Plasma coupled interface, or from User defined where the Heat source is manually entered.
Note this heat source is equivalent to adding a Heat Source node in the Heat Transfer coupled interface and select Heat source for gas as the Heat source.
If you build the multiphysics model from scratch — that is, you add the three single physics interfaces first and then add the Nonisothermal Plasma Flow node manually — there are some settings that need to be modified from the their default values:
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The Fluid type should be set as either Ideal gas or Gas/Liquid in the Thermodynamics, Fluid section of the Fluid node in the Heat Transfer coupled interface.
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The Calculate thermodynamic properties and the Convection checkboxes should be selected in the Transport Settings section in the main node of the Plasma coupled interface.
It is recommended to build the multiphysics model from one of the predefined multiphysics interfaces instead, as these necessary modifications have been taken care of in all of these multiphysics interfaces. The multiphysics interfaces are located under Plasma > Nonisothermal Plasma Flow when building a model using the Model Wizard.
If a physics interface is deleted and then added to the model again, then in order to reestablish the coupling, you need to choose the physics interface again from the Plasma, Fluid flow or Heat transfer lists. This is applicable to all multiphysics coupling nodes that would normally default to the once present interface. See Multiphysics Modeling Workflow in the COMSOL Multiphysics Reference Manual.