### 17.3.5. Physical Models Parameters

Material Properties
`realeos liquid prop`
Type | Integer
Default Value | 1
Description | This parameter controls whether liquid saturation properties are extracted using the Rackett equation, which is a function of temperature (realeos liquid prop = 1), or using the full equation of state, which is a function of both temperature and pressure (realeos liquid prop = 2) — the latter is more accurate. For details, see Real Gas Liquid Properties in the CFX-Solver Theory Guide.
Combustion Models
`coupled scalars`
Type | Logical
Default Value | f
Description | All combustion models that solve for the mixture fractions of the reactants and products (single or multiple step reaction models), are solved using a coupled multigrid linear solver. This means that all of the mixture fraction equations are solved simultaneously, with the mixture mass transfer source terms linearized in each equation. Under certain conditions, this coupling procedure can fail, leading to oscillatory convergence or divergence. In this case, you can disable the coupled solver and switch to a segregated approach to solving the mixture fraction equations. This is achieved by setting this parameter to `'f'`.
`use kolmogorov ts for extinction`
Type | Logical
Default Value | f
Description | This parameter is provided for backwards compatibility with the first release of the extinction model. It is not recommended for use (leave at default setting of `'f'`, which uses the turbulence time scale for the flame extinction model). When set to `'t'`, the Kolmogorov time scale is used in the extinction model (not recommended).
Parallel and Partitioner Control
`parallel optimization level`
Type | Integer
Default Value | 0
Description | This parameter applies pre-set optimizations to improve parallel performance. Increasing the value of this parameter will increase the expected performance gain, but it may also reduce robustness in some cases. Other expert parameters are available to control individual performance optimizations.
`part adjacency output`
Type | Logical
Default Value | f
Description | This parameter controls whether the partition adjacency data is stored in the `.par` file.
`part cvs weighting`
Type | Logical
Default Value | f
Description | This parameter can be used to enable a more complex, experimental algorithm for parallel partitioning. This method attempts to assign different weights to each node/vertex in the domain, depending on the complexity of the elements surrounding a vertex. It attempts to make a more balanced partitioning for mixed element grids.
`part mmesh intersect option`
Type | Integer
Default Value | 0

Description

This parameter can be used to enable a modified algorithm for partitioning moving mesh cases. The modified algorithm recognizes moving domain interfaces. A value of `1` selects the newer algorithm. A value of `0` selects the original algorithm.

The modified algorithm aims to keep both sides of a GGI interface within the same partition, potentially improving convergence behavior in parallel and reducing communication requirements between partitions.

This expert parameter affects parallel runs only; it has no effect on serial runs.

`rad data in par file`
Type | Logical
Default Value | f
Description | This parameter controls whether the radiation mesh is stored in the `.par` file.
Turbulence Models
`apply ic fluctuations for les`
Type | Logical
Default Value | f
Description | If set to `'t'`, to force the application of velocity fluctuations when restarting an LES. This is most useful when using a RANS solution as this initial guess. For details, see LES Initialization.
General Grid Interface
`force intersection`
Type | Logical
Default Value | f
Description | On all GGI interfaces (fluid-fluid attachments, periodicity and frame change interfaces), the solver performs an intersection procedure to connect the two sides of the interface together. This procedure is CPU intensive, so the result of the intersection is stored in the outgoing results file, for future use (for example, upon restart of the simulation). You can force a re-intersection of the GGI interface if desired, upon restart, by setting this parameter to `'t'`. It is rare that this parameter should be needed, as it generally only results in wasted CPU time upon a restarted simulation.
`ggi vertex weighting value`
Type | Integer
Default Value | 2
Description | Weighting applied to GGI vertices during partitioning. A larger value assigns a larger weight to vertices on GGI boundaries to account for the fact that the assembly effort is higher at GGI interfaces. For more information, see Node-based and Element-based Partitioning.
`mpf ggi force flow balance`
Type | Logical
Default Value | f
Description | Usually flow balance is not enforced at GGI interfaces for multiphase flows. By setting the value of this parameter to 't', the code will enforce flow balance. This can help with the convergence of many inhomogeneous multiphase flows that include such interfaces.
`stage energy closure option`
Type | Integer
Default Value | 2
Description | With option = 2, conservation of rothalpy is enforced; with option = 1, conservation of rothalpy is not enforced.
Miscellaneous
`asm momentum drift flux`
Type | Logical
Default Value | f
Description | This parameter adds the ASM drift fluxes into the momentum equation.
`meshdisp phase angle convention`
Type | Integer
Default Value | 1
Description | This parameter selects which convention is used for specifying the mesh displacement phase angle. A value of 1 (default) selects the convention of specifying the magnitude of the nodal diameter plus the direction of the traveling wave; this convention is described in Case 3: Blade Flutter. A value of 0 selects the convention of specifying a positive or negative value of the nodal diameter.
`tbulk for htc`
Type | Real
Default Value | 300 K

Description

When the Heat Transfer Coefficient (HTC) is computed for a temperature specified wall, by default a near-wall fluid temperature is used for a temperature scale. However, for consistency with traditional 1D analyses, you may want to enter a reference bulk temperature to compute the HTC. This parameter is that reference value.

Thus the HTC computed when this parameter is provided is equal to the local heat flux calculated by the solver divided by the difference of the specified wall temperature and this specified bulk temperature.

`topology simplification`
Type | Logical
Default Value | t
Description | This parameter controls internal mesh topology simplification. It can improve performance for models with a large number of 2D primitives. While the simplification will not change the output regions (in CFD-Post), it may lead to small differences in solution results due to rounding errors, especially for single precision solutions. Note that topology simplification does not take effect for models involving System Coupling or radiation. Also note that topology simplification cannot be used if there are region changes introduced by re-reading CCL during a solver run (for example, using the Edit Run In Progress command).
`transient initialisation override`
Type | Logical
Default Value | f
Description | When set to `'t'`, enables solver default values to be used for initialization in a transient simulation.

Release 18.2 - © ANSYS, Inc. All rights reserved.