Finite Volume Solvers Reference

In Simcenter STAR-CCM+, most solvers use the finite volume solution method. Finite volume solvers have common properties.

Common Properties

Unless you are thoroughly familiar with the discretization techniques that are used in Simcenter STAR-CCM+, do not change any properties within the Expert category. The values in that category have been optimized for accuracy and performance.

Reconstruction Frozen

When On, Simcenter STAR-CCM+ does not update reconstruction gradients with each iteration, but rather uses gradients from the last iteration in which they were updated. Activate Temporary Storage Retained in conjunction with this property. This property is Off by default.

Reconstruction Zeroed

When On, the solver sets reconstruction gradients to zero at the next iteration. This action means that face values used for upwinding (Eqn. (905)) and for computing cell gradients (Eqn. (917) and Eqn. (918)) become first-order estimates. This property is Off by default. If you turn this property Off after having it On, the solver recomputes the gradients on the next iteration.

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 This is a debugging option that can result in non-recoverable errors and wrong solutions due to outdated values. When activated, it causes all those actions to be skipped which are typically orchestrated by a solver, such as allocating storage, updating boundary conditions and gradients, triggering the computations to assemble the linear system (such as the computation of source terms for the transport equation, which may implicitly trigger dependent computations), computing corrections for the solution variable, removing storage, and so on.

A safer way to prevent the solver from applying any corrections to the transport variable is to set AMG Linear Solver > Max Cycles to zero. In that case, storage is managed properly and boundary conditions (and in some cases gradients) are updated, but the computation of corrections is skipped. Hence, the savings in CPU time is slightly smaller but there is no additional risk of non-recoverable errors.

If a non-recoverable error associated with missing or uninitialized storage is encountered when using Solver Frozen, deactivate Solver Frozen during solution initialization for at least one iteration with the Temporary Storage Retained option activated before re-activating the Solver Frozen option. There still exists a risk of using outdated values somewhere without any indication.

Temporary Storage Retained

When On, Simcenter STAR-CCM+ retains additional field data that the solver generates during an iteration. The particular data retained depends on the solver, and becomes available as field functions during subsequent iterations. Off by default.

Right-Click Actions

Restore Default Settings

When selected, restores the solver to its default settings, that is, the settings that the solver has when it is created from a new simulation.