### 23.3.1. Basic Settings Tab

The following sections describe the options available on the Basic Settings tab for Mesh Adaption.

#### 23.3.1.1. Region List

Region List contains the names of all 3D Regions and Assemblies in the problem. Select any or all of the 3D regions to be used for mesh adaption.

Note: Mesh adaption cannot be used in multidomain simulations or in cases with external solver coupling. Mesh adaption also cannot be used for transient, mesh-motion, radiative-tracking, or particle-transport cases.

#### 23.3.1.2. Save Intermediate Files

If Save Intermediate Files is selected, an intermediate results file is saved immediately before each mesh adaption step begins. At the end of the run, these intermediate files are stored in a subdirectory with the same name as the run, in the directory that contains the CFX-Solver results file.

#### 23.3.1.3. Adaption Criteria

For each adaption step, and for each mesh element, the adaption criteria are applied, and mesh elements meeting the adaption criteria are refined. There are two methods of specifying how the adaption criteria are specified. For details, see Adaption Method.

##### 23.3.1.3.1. Variables List

The Variables List is used to select the variables that make up part of the Adaption Criteria.

During the adaption process, if only one variable is selected, the value of the variable is observed for each element defining the selected regions specified by the Region List. The maximum variation in value of the variable along any edge of an element is used to decided whether the element is to be modified. If multiple variables are selected, the maximum of variation of all the variables for a given element is used to decide whether or not an element should be modified.

To save unnecessary processing, it is important to ensure that variables selected will vary during the calculation. For instance, do not select Density as a variable for an incompressible flow calculation.

##### 23.3.1.3.2. Max. Num. Steps

The number of steps that the adaption process performs is specified by Max. Num. Steps. It is recommended that you select a number between 1 and 5.

Note: If CFX-Solver runs on the CFX-Solver input file and finishes normally, this number of Adaption Steps will take place. If CFX-Solver is stopped and then restarted from the results file produced, only the remaining number of Adaption Steps will take place in the restarted run.

##### 23.3.1.3.3. Option

The number of nodes in the final mesh generated by the adaption process is controlled by the value selected in Option.

Select Final Number of Nodes, to specify the number of nodes in the final mesh, or Multiple of Initial Mesh, which enables specification of the number of nodes in the final mesh as a multiple of the initial mesh.

If Multiple of Initial Mesh is selected, it is also necessary to specify a Node Factor multiplier greater than 1.2. If Final Number of Nodes is selected, then specify the number of Nodes in Adaption Mesh that is no more than a factor of five greater than the number of nodes in the initial mesh.

Note: The final mesh will not contain exactly the number of nodes specified in either case. For details, see Mesh Adaption in the CFX-Solver Theory Guide.

#### 23.3.1.4. Adaption Method

The Adaption Method used by the adaption process to apply the Adaption Criteria is controlled by the options specified in the Adaption Method section of the form.

##### 23.3.1.4.1. Option

The Adaption Method is specified as either Solution Variation, or Solution Variation * Edge Length.

If Solution Variation * Edge Length is selected, the Adaption Criteria takes account of both the variation of the solution variable over the edge of the element and the length of the edge. The result of having applied the Adaption Criteria to each edge of an element is then multiplied by the length of the edge. The maximum value of all the edges of the element is used to decide whether an element is to be refined. This means that in areas of the flow where the solution variation is similar, adaption will take place preferentially in regions where the mesh length scale is largest.

##### 23.3.1.4.2. Minimum Edge Length

When Solution Variation is specified by Option, the Adaption Criteria is applied using only the maximum variation of a solution variable across any edge associated with an element. This option does not use the length of the edge in the calculation. In this case, consider specifying a Minimum Edge Length to avoid refining the mesh too far at a discontinuity in the solution. For details, see Mesh Adaption in the CFX-Solver Theory Guide.

#### 23.3.1.5. Adaption Convergence Criteria

The convergence criteria used to specify when the CFX-Solver stops running on the original and intermediate meshes is specified in the Adaption Convergence Criteria section of the form. The available parameters are the same as those used to determine the final convergence of the solution. For details, see Basic Settings Tab.

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