Defining the Electrical Conductivity

When modeling electric currents in conducting materials, you specify the material electrical conductivity σ, which defines the relationship between the electric current density J and the electric field E according to Ohm's law.

For more information, see Electrical Conductivity: Generalized Ohm's Law and Eqn. (4234).

The procedure for defining the electrical conductivity depends on the region type. For fluid and solid regions, you specify the electrical conductivity under the physics continuum associated with the region:

  1. Expand the relevant Continua > [Physics Continuum] > Models > [Material Model] > [Material] node.
When using the Multi-Part Solid model, you can define different electrical conductivities for different solid parts within the same physics continuum. When using the Multi-Component Gas and Multi-Component Liquid models, you define the effective electrical conductivity of the mixture (you cannot define the electrical conductivity as a function of the conductivities of the components). When using single-component models such as the Gas and Solid model, you specify the electrical conductivity of the single material.
  1. For each material node, select the Material Properties > Electrical Conductivity node and choose the Method for defining σ.
    • For fluids and isotropic solids, you specify σ as a scalar.
    • For anisotropic solids, you specify σ as a tensor (see Tensor Quantities).

      In this case, also specify the local orientation for the tensor at the region level, using the Regions > [Region] > Physics Values > Electrical Conductivity Orientation node (see Electrical Conductivity Reference).

    • When using harmonic balance models, you specify σ as a complex number by defining either its real and imaginary parts, or its phase and magnitude.
  2. If you define the electrical conductivity using the Table(T) method, set the Electrical Conductivity > Resistivity Interpolation Option.
    The Resistivity Interpolation Option allows you to use a resistivity interpolation method for calculating the conductivity instead of a conductivity interpolation. This can produce more accurate results for materials in which resistivity varies linearly or monotonically with temperature. For more information on the available methods, see Electrical Conductivity Reference.
In fluid regions, you can artificially raise the electrical conductivity of a gas by specifying a minimum electrical conductivity. For example, in a plasma flow simulation, you can artificially raise the electrical conductivity of the gas in a particular region to model the ignition of an electrical spark. The current flow through this artificial channel heats up the gas so that the gas conductivity soon exceeds the artificial minimum conductivity. To specify the minimum electrical conductivity within a fluid region:
  1. Expand the relevant [Fluid Region] > Physics Conditions node.
  2. Select the Electrical Conductivity Constraint Option and set Option to Minimum.
  3. Select the [Fluid Region] > Physics Values > Minimum Constraint Electrical Conductivity node, and set the minimum electrical conductivity to a value of your choice.
In Simcenter STAR-CCM+, you can model porous materials using fluid regions with the Porous Media model.
  1. To set the electrical conductivity of porous materials, define the conductivity of the fluid and solid phases independently:
    1. To set the conductivity of the fluid, select the relevant [Fluid Physics Continuum] > Models > [Material Model] > [Material] > Material Properties > Electrical Conductivity node and define σ as required.
      If the Electrodynamic Potential model is only active in the solid phase and not in the fluid continuum, this step is not necessary.
    2. To set the conductivity of the solid phase, select the relevant [Fluid Physics Continuum] > Models > Porous Media > Porous Phases > [Solid Phase] > Models > [Material Model] > [Material] > Material Properties > Electrical Conductivity node and define σ as required.