Electric Potential Solver Reference

The Electric Potential solver controls the solution of the electric potential in electrostatic and electrodynamic simulations.

Electric Potential Solver Properties

Under-Relaxation Factor
During the iterative process, the Electric Potential solver under-relaxes the changes in the solution, as:
ϕn+1=ϕn+ωϕ′
where ω is the under-relaxation factor. At each iteration, the under-relaxation factor governs the extent to which the new solution replaces the old one.
The default value is 1.0. If residuals show solution divergence and do not decrease, reduce the under-relaxation factor.
Solver Frozen
When On, the solver does not update any quantity during an iteration. It is Off by default. This is a debugging option that can result in non-recoverable errors and wrong solutions due to missing storage. See Finite Volume Solvers Reference for details.
Temporary Storage Retained
When activated, Simcenter STAR-CCM+ retains the electric potential residuals computed at each iteration and makes them available as field functions:
  • Electric Potential Correction AP Coefficient
  • Electric Potential Correction Residual
  • Electric Potential Gradient
  • Electric Potential Recon
Use this option to make the electric potential gradient available when the Electric Potential solver is frozen. See Solver Frozen.
Secondary Gradients Limiter
This option is only intended for use when stability issues occur with Secondary Gradients On for electric potential.
When Secondary Gradients Limiter is activated, and Secondary Gradients are On, the secondary gradients are limited to promote convergence stability. Activating the Secondary Gradients Limiter has a lower cost on accuracy than turning off Secondary Gradients.
AMG Linear Solver
The electric potential is solved by the third party Hypre linear equation solver. Hypre provides some of the most commonly-used Krylov-based iterative methods to be used in conjunction with its scalable preconditioners. For more information, see HYPRE.

The Hypre linear equation solver properties are specified in the AMG Linear Solver node.

Expert Initialization

Expert Initialization
Allows the initialization of electric potential before running the simulation. High current densities can exist at boundaries due to highly nonlinear kinetics—especially during initial iterations. This can lead to massive consumption / production of electrochemical species concentrations at the boundaries, and result in divergence. Instead of using ramps for the other solvers to allow the electric potential to run first, you can use the Presolve option to solve the electric potential during the initialization phase.
Method Corresponding Sub-Node
None

The Electric Potential Solver begins to run at the same time as other solvers—unless using ramps.

 None
Presolve

Initializes the electric potential field.

 Presolve
Prior to running the electric potential presolver, Simcenter STAR-CCM+ initializes the electric potential as follows:
Parts-Based Initialization Region-Based Initialization
Occurs when all regions are associated with parts, and all interfaces are associated with contacts.

Simcenter STAR-CCM+ uses a linear least squares based method to automatically initialize the electric potential throughout all parts in which the electrochemical reactions model is active—and any corresponding electrically connected parts. In all other parts, Simcenter STAR-CCM+ uses values that you set for the electric potential initial conditions.

 Occurs when any of the regions are not associated with parts, or any of the interfaces are not associated with contacts.

Simcenter STAR-CCM+ displays a message which indicates that it is proceeding with region-based electric potential initialization.

Simcenter STAR-CCM+ uses a linear least squares based method to automatically initialize the electric potential throughout all regions in which the electrochemical reactions model is active—and any corresponding electrically connected regions. In all other regions, Simcenter STAR-CCM+ uses values that you set for the electric potential initial conditions.

During the initialization phase, the Electric Potential Solver runs until either the Convergence Tolerance is satisfied or until Maximum Iterations are reached.