Modeling Magnetohydrodynamics (MHD)

In electromagnetic applications involving electrically conducting fluids, such as molten metals, electrolytes, and plasmas, Simcenter STAR-CCM+ allows you to account for the interaction between the conducting fluid and the magnetic field.

A conducting fluid in relative motion to a magnetic field induces an electric current density JL (see Eqn. (4369)), which causes the fluid to experience an additional body force, known as the Lorentz force (see Eqn. (4377)). The MHD models in Simcenter STAR-CCM+ account for these effects in both the fluid flow solution and the electric potential solution (see Magnetohydrodynamics (MHD)).

To define the magnetic field, you can either prescribe the magnetic flux density within the fluid region, or calculate the magnetic flux density using one of the Simcenter STAR-CCM+ magnetic vector potential models. The first approach is suitable for analyses in which the magnetic flux density induced by the electric current density JL can be neglected. For more information, see One-Way Coupled and Two-Way Coupled MHD.

  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 General Simulation Process.
  2. Create physics continua and assign them to the relevant regions.
  3. In each physics continuum, activate physics models as required. To model the interaction between the conducting fluid and the magnetic field, include the following physics models:
    Group Box Physics Model
    Space Either Three-Dimensional or Axisymmetric
    Time Either Steady or Implicit Unsteady
    Material Either Gas, Liquid, Multiphase, Multi-Component Gas, or Multi-Component Liquid
    Flow Any
    Optional Models Electromagnetism
    Electromagnetism
    • To model the interaction between the conducting fluid and a prescribed magnetic flux density, activate the following models:
      1. Electrodynamic Potential
      2. One-Way Coupled MHD
    • To model the interaction between the conducting fluid and the total magnetic flux density, which is calculated by Simcenter STAR-CCM+, activate the following models:
      1. Either Finite Volume Magnetic Vector Potential, Finite Element Magnetic Vector Potential, Transverse Magnetic Potential, Harmonic Balance FV Magnetic Vector Potential, or Harmonic Balance FV Transverse Magnetic Potential
      2. Two-Way Coupled MHD
      3. You can also activate the following optional models:
        • Eddy Current Suppression—neglects the contribution to the electric current density coming from eddy currents.
        • Electrodynamic Potential—solves for the electric potential, which also contributes to the total electric current density.

    For more information on the MDH models, including the associated field functions and region settings, see One-Way Coupled MHD Model Referenceand Two-Way Coupled MHD Model Reference.

When using the One-Way Coupled MHD model, define the magnetic flux density within the relevant regions:
  1. Expand the Regions > [Region] > Physics Values node.
  2. Select the Prescribed Magnetic Flux Density node and specify the magnetic flux density vector profile, as appropriate.
  3. Complete the simulation set up as required. This step includes defining the electrical conductivity of the fluid and, when modeling two-way coupled MHD, the magnetic permeability.
    For guidelines on modeling electric currents and magnetic fields, see Modeling Electric Currents and Modeling Magnetic Fields.