Modeling Electrostatics

The following steps show how to model electric fields induced by static or quasi-static distributions of electric charges.

In electrostatic applications, Simcenter STAR-CCM+ solves Eqn. (4272) for the electric potential and then calculates the associated electric field E , and electric flux density D .

  1. Before you set up the physics continua, prepare the required geometry, regions, interfaces, and mesh, as appropriate to your analysis.
    For information on these general operations, see 常规模拟过程.
    When you model electrostatic conductors, you do not need to generate a mesh for the conductors. The conductors negate the electric field in their volume and so there is nothing to solve in these regions.
  2. Create physics continua and assign them to the relevant regions.
  3. In each physics continuum for which you want to model Electrostatics, include the following models:
    Group Box Physics Model
    Space Either Three Dimensional, Two Dimensional, or Axisymmetric.
    Time
    • To run a static analysis, where the electric charge density does not depend on time, activate the Steady model.
    • To model time-dependent electric charge distributions, activate the Implicit Unsteady model. As Eqn. (4272) does not contain any transient term, the analysis is still static. At each time-step, Simcenter STAR-CCM+ computes the electric potential induced by the electric charge density defined at that time-step.
    Material Choose the relevant material model.
    Optional Models Electromagnetism
    Electromagnetism Electrostatic Potential
    If relevant, you can use the Electrostatic Potential model together with the following models:
    • Electrochemical Species—accounts for the distribution of electrochemical species within a fluid (see 离子组分通量建模).
    • Plasma—models non-LTE plasma (see 冷（低温）等离子体建模).
    • Lagrangian Multiphase—models the motion of electrically charged material particles (see ).
  4. Expand the [physics continuum] > Models > [Material Model] > [Material] > Material Properties node.
  5. Specify the Permittivity of the material.
    For more information on the available methods, see 材料属性.

    When using any of the methods for tensor profiles (Anisotropic, Orthotropic, or Transverse Isotropic), you specify the local orientation for the tensor at the region level, using the Regions > [Region] > Physics Values > Permittivity Orientation node (see 材料属性).

By default, the electric charge density ρ within a region is set to zero. To define an electric charge density for the region:
  1. Expand the relevant Regions > [Region] > Physics Conditions node.
  2. Select the Electric Charge Density Source node and activate Electric Charge Density User Source.
  3. Select the Physics Values > Electric Charge Density User Source node and specify ρ as a scalar profile.
  4. When ρ is a nonlinear function of the electric potential, you can specify the nonlinear relationship by setting the Electric Charge Density Source Potential Derivative. This generally improves the convergence of the electric potential solver.
At the domain boundaries, specify either the electric potential or its normal derivative. To define the boundary conditions:
  1. Expand the relevant Regions > [Region] > Boundaries > [Boundary] > Physics Conditions node.
  2. Select the Electric Potential Specification node and set Method to either:
    • Specific Electric Flux
    • Electric Flux
    • Electric Flux Density
    • Electric Potential
    • Floating Potential
  3. Expand the boundary Physics Values node and specify the boundary value under the relevant value node.
  4. If you have set Electric Potential Specification to Electric Flux, select the Electric Flux Distribution node and choose the assumption for determining the spatial distribution.
    The choice of spatial distribution depends on the case you are modeling. For example, if you are delivering charge using conducting electrodes, you can use the Uniform Electric Potential assumption.
To model the interface between a gas and a dielectric (non-conducting) material, you specify the surface charge density at the interface. Example applications include ionic wind and capacitatively coupled plasma (see Modeling Ionic Species Flux and Modeling Cold, Non-Thermal Plasma ).

To specify the surface charge density at a contact interface:

  1. Expand the relevant Interfaces > [Interface] > Physics Conditions node.
  2. Select the Surface Electric Charge Option node and set Method to Surface Charge Density.
  3. Select the Physics Values > Surface Charge Density node and specify the appropriate surface charge density profile.
    You can also set a specific electric flux or total electric flux value on an interface using the Electric Flux Source Option node.