Named selections are aliases for collections of regions. When importing a mesh from an Ansys Meshing file, you can preserve these named selections based on where they were created:

When importing a mesh from an Ansys Meshing file, you can generate pairs of new named selections, each pair representing the two sides of certain existing named selections.

To generate new named selections:

In order for an existing named selection to be eligible for use in generating new named selections, the existing named selection must consist of exactly two primitive regions. The two new named selections correspond to the two primitive regions.

Also see Named Selections Involving Interior Faces in the Meshing User's Guide.

The Contact check box, when selected, makes contact detection settings available.

When importing Ansys Mesh files (.cmdb / .dsdb files), it is possible to select Detection Method > Read to read contact information from the file or to select Detection Method > Detect to use the contact detection methods to determine whether regions within the mesh are "in contact" with each other. CFX-Pre uses the Mechanical application contact detection methods to determine which mesh volumes should be placed within each mesh assembly and which 2D regions are connected.

The Read Method setting can be set to Modify Topology meaning that CFX-Pre will create connections between pairs of regions according to the contact information read from the Ansys Meshing file. The topology is modified as part of this process, which can result in two or more bodies becoming part of a single assembly. When using the Create Regions option, the contact information read from the file will result in each contact being represented as composite regions on each side of the contact definition allowing easy identification of the contact regions. Using the Create Regions option will not modify the underlying topology of the mesh.

The Detection Between setting can be set to Bodies or All Contact. When using the Bodies option, 2D regions will be matched between different bodies. This is the default option and should result in bodies that are "close" to one another being placed in the same mesh assembly. If automatic domain interface generation is selected, interfaces will be generated between such regions. When using the All Contact option, CFX-Pre will still recognize contact between discrete bodies, but in addition, it will look for contact between 2D regions within the same "body", or "volume". This can result in unexpected behavior, such as adjacent surfaces being considered "in contact" and hence this is not the default option, but in some cases, where there are non-matched 2D mesh regions within a mesh volume, it can help generate "internal" interfaces.

The tolerance that is used in detecting contact can be altered and it is possible to define it relative to the local geometry size, or as an absolute spatial value.

If CFX-Pre is set to read contact information from the file, then it will import only connections that connect two single regions. Connections connecting multiple regions to a single region, or multiple regions to multiple regions, will be ignored. Also, contact detection works only within a single file; CFX-Pre will not read or detect contact between meshes that are imported from different files.

If the Meshing application is set to generate connections automatically, you can set the Global Contact Setting option to Group By > None to generate only single region to single region connections. For more details, see Generation of Contact Elements in the Meshing User's Guide.

This check box determines whether or not each imported region is prefixed with the name of the zone within which it is defined.

Each element section that specifies the topology of elements within the CGNS file may or may not imply a grouping of these elements that is important. If the grouping of elements within each element section is important, this option should be selected so the grouping is preserved within CFX-Pre.

Element sections can be 2D or 3D or a mixture of both, and as such can form 3D regions or 2D regions in CFX-Pre.

The way they are grouped depends on vendor interpretation of the CGNS standard.

This check box determines whether or not to import boundary conditions as regions.

This check box determines whether or not to import families of elements, or faces as regions.

This check box determines whether or not to import zone interfaces (that is, 1-to-1 and GGI connections) as regions.

Consider a CGNS file with one zone, Zone 1, made up of four element sections (ES1 and ES2 defining the 3D elements, and ES3 and ES4 defining the 2D elements). It also contains 2D boundary conditions BC1 and BC2.

These element sections, ES1 and ES2, could consist of, for example, hexahedral elements in ES1 and tetrahedral elements in ES2. In this case, the groupings of elements into the first two element sections appears to be due to their topological identity. However, this may or may not be the case and you must decided as to whether importing these groupings is important.

In this case, it may be that ES1 and ES2 should be combined by clearing the Create Regions From: Element Sections option. Another possibility is that ES1 may be a subregion of mesh that should be kept separate (that is, it will be set up as a subdomain). If that were the case, Element Sections should be selected.

If BC1 is defined on all the faces in ES3 and BC2 is defined on all the faces in ES4, then it will probably not be necessary to select Boundary Conditions if Element Sections is selected, as this would introduce complexity in the region definitions (that is, composites would be defined). However if the groupings of ES3 and ES4 are different from the groupings in the boundary conditions then Create Regions From: Boundary Conditions should be selected.

When this toggle is selected, a mesh is read from a single base specified by the CGNS base to read number. If your CGNS file contains only a single base, you should leave the number set to 1. If it contains more than one base, you should specify the base number from which to read. If the base number specified does not exist, an error will be raised. If it does not contain a valid mesh then a mesh will not be imported.

If you disable the Read Only One CGNS Base toggle, then CFX-Pre will look for meshes in all bases and import them. If multiple assemblies are imported and they overlap, then the mesh will be invalid within CFX-Pre unless assemblies are transformed in some way.

This toggle controls 3D region import from the .grd file only. When selected, 3D regions in the .grd file will be imported into separate 3D primitives in CFX-Pre. If you do not select this option, all mesh elements will be imported into a single 3D primitive that is uniquely named by the import process. 3D regions defined in the .gci and .bcf files are always imported.

When importing CFX-TASCflow meshes, the only grid connections that are imported automatically are "many-to-one" contiguous topology connections that are specified as one-to-one node pairings.

"Many-to-one" contiguous topology connections that involve any number of many-to-one node groupings are ignored and a warning message is issued; however, the two sides of the connection are preserved as a pair of 2D regions on which a GGI Connection can be defined. You should recreate the connection in CFX-Pre using a Fluid-Fluid Domain Interface. For details, see Creating and Editing a Domain Interface. In some cases, if you have not created regions in CFX-TASCflow on each side of an interface, you will not be able to recreate it in CFX-Pre because there will be no region available for selection. If this occurs, you should explicitly create regions in CFX-TASCflow before importing the mesh into CFX-Pre.

"Many-to-one" periodic topology connections are always removed with a warning message issued. You should recreate the connections using a periodic domain interface. For details, see Creating and Editing a Domain Interface.

The regions associated with periodic boundary conditions are imported, but you will need to assign the regions to a periodic domain interface.

Embedded grids, along with the parent grid, are automatically imported into separate assemblies in CFX-Pre. The many-to-one topology connections on the interface between the embedded grid and the parent grid will be removed and a warning issued. You will need to create fluid-fluid domain interfaces between the embedded grid and the parent grid. For details, see Creating and Editing a Domain Interface.

The Retain BlockOff toggle is selected by default. There is no harm in leaving this on, but it is not required unless user defined block-off is defined in the .bcf the file, and you want it to remain blocked-off (ignored).

Porous and CHT objects in the .bcf file are ignored, and must be manually created in CFX-Pre after importing the grid. You should make sure that a 3D volume region was defined in the grd file for the porous or CHT object location prior to import.

By default, CFX-Pre will look in the same directory as the .grd file to locate the .bcf file. If the .bcf file is located elsewhere, you can browse and select the file.

You should delete any regions from the .grd file that are not needed.

If necessary, you can force all "user defined" regions to be included in a .grd file by executing the following command at the TASCtool command prompt:

TASCtool{}: write grd all_regions_to_grd=on

This is usually not needed because you can import regions from the .gci file directly (see below).

Note that when faces are referenced by more than one named region, the import process will resolve this conflict such that faces are not referenced by more than one region.

The regions associated with the boundary conditions defined in the .bcf file are imported into CFX-Pre. The boundary condition physics definitions are ignored and must be defined in CFX-Pre.

The CFX-TASCflow symmetry/slip boundary condition should be recreated as either:

Regions in the .gci file defined in (i, j, k) coordinates (such as boundary conditions) are imported if the Use GCI file toggle is selected on the Advanced Options tab. By default, CFX-Pre looks in the same directory as the .grd file for the location of the .gci file. You should select the location of the .gci file by clicking on the browse icon if it is located elsewhere.

Regions defined in physical space (x, y, z coordinates) are always ignored.

An alternative method for reading the .gci file is to force all regions to be included in the .grd file. For details, see Regions in the .grd file.

You can create multiple domains from a single .grd file if it contains multiple 3D regions or GGI connections. For an MFR grid, a separate assembly will be created for each noncontinuous grid region. This enables a multiple frame of reference (MFR) case to be easily recreated in CFX-Pre from a single mesh import.

Grids from CFX-TASCflow TurboPre usually contain many named regions that may not be required to set up the problem in CFX-Pre. You might want to remove some of these regions before importing the grid to speed up the import of the mesh and simplify the imported mesh.

In CFX-TASCflow TurboPre, you can create multiple copies of blade passages. The ‘open ends’ of the machine section will use a periodic connection. These must be recreated in CFX-Pre using a periodic domain interface. For details, see Creating and Editing a Domain Interface. The internal connection between blade passages can be connected in CFX-TASCflow TurboPre using an automatic periodic boundary condition. If such a connection is used you will have to manually reconnect each passage in CFX-Pre. You might therefore want to define a many-to-one topology connection for one-to-one grid connections so that passages are connected by CFX-TASCflow TurboPre as topology connections (which import immediately). For details, see Grid Connections Processed (in the .grd file).

CFX-TASCflow does not have units checking, whereas CFX-Pre does. Grid numbers will be imported using the units specified on the Import Mesh dialog box. You should convert all units in the properties and parameter files within TASCflow into SI units (kg, meter, second) prior to import.

The Split Symmetry Planes option is on by default. Symmetry planes that are defined by more than one CFX-4 region will be split so that each definition is imported. For example, a symmetry plane that is defined on two sides of a 3D region will be split into regions named <regionname>1 and <regionname>2, and so on, where <regionname> is the original name of the symmetry plane in the CFX-4 file.

CFX-Pre can import problems defined in Cylindrical Coordinate (x, r, ) form from CFX-4. The problem is converted to Cartesian Coordinates (x, y, z) by the import process. The resulting CFX-Solver input file will not be written in cylindrical coordinates. You must select the Import from Cylindrical Coordinates option to successfully import a CFX-4 cylindrical coordinate problem.

You can enable this toggle if you want to import a mesh created as a 2D mesh on an axisymmetric section in CFX-4. This is different to a mesh defined using cylindrical coordinates; however, it can also use an (x, r, ) coordinate system. The CFX-4 mesh must be only 1 element thick in the k direction to use this option.

The Number of Planes value enables you to create additional planes in the direction within the original 2D mesh to create a 3D problem. This will increase the number of elements in the k direction, but does not change the extent of the mesh.

The Angle value should be the angle of the mesh section in degrees. Because the mesh is only one element thick, then is the same for all nodes.

If you have a CFX-4 MFR case, it can easily be imported into CFX-Pre and recreated.