ANSYS ICEM CFD - Unigraphics Interface

STAR-CD Interface

The translator creates the following STAR-CD input files:

Element file: contains the elements' number, connectivity and ICTID
Node file: contains the nodes' number and cartesian coordinates
Boundary file: contains the shell elements' number and connectivity, their ICTID number and their region name
Command file: contains the ctable (ICTID, element type, color and region name) and the commands to read the different files in PRO-STAR.
Coupling file: contains the elements' coupling in case of non-C0 interfaces.

The file name extensions depend on the STAR-CD version, as indicated in the table below.

File type	version 3.0.5.0 or STAR-LT	version 3.1.0.0
Element file	`elem`	`cel`
Node file	`node`	`vrt`
Boundary file	`bread`	`bnd`
Command file	`inp`	`inp`
Coupling file	`cp`	`cpl`

Creating the STAR-CD Input Files

The translator writes the STAR-CD input files using an unstructured domain file and its corresponding boundary conditions file. To create the STAR-CD input file, select the translator "STAR-CD" in the "Output" menu from the ICEM CFD/CAE Manager. After clicking "STAR-CD input", you can specify options for the STAR-CD interface:

select an existing unstructured domain file
"Prefix of output file(s)" : give the prefix for the STAR-CD files
"Boundary Conditions File" : give the path of the boundary conditions file
"STAR-CD Version No." : give the STAR-CD version number
"Starting ICTID number is " : give the starting ICTID number (default is 5)
"Output type" : option to write the element, node and boundary files in ASCII or in Fortran-binary
"Write node file?" : option to write or not the node file
"Write element file?" : option to write or not the element file
"Write shells in element file?" : option to write or not the tagged shell elements in the element file
"Write boundary file?" : option to write or not the boundary file
"Boundaries to write" : option to write all boundary elements in the boundary file, or only those defined with a boundary condition type
"Check face orientation?" : option for boundary element face orientation (useful in post-processing flux calculations).
"List of priority families in orientation" : an ascending list of the most important families for the above orientation (see notes below).
"Flow regime?" : select the flow regime for commands in the .inp file
"Inlet Model?" : option to specify the inlet model (Mix1 or Keps)
"Energy Equations Required": option to write command "temp,on" in command file.
"Scaling": option to scale the model. The X, Y and Z scaling factor will multiply the x, y and z coordinates respectively.

Boundary element face orientation

With "Check face orientation?" selected, the interface will attempt to orient all of the elements at surface family boundaries such that each element in a family has the same face number facing outward.

In the case that not all element orientations can be resolved, there is a field ("List of priority families in orientation") in which you can specify the most important families to be oriented. You can specify these actual family names in a list separated by spaces, for example:

        OUTLT INLET FAM3 ... FAMn

If none of these families are adjacent, then all families listed should be guaranteed proper orientation. In the case that two of these families are adjacent, that family appearing later in the list will be given priority. Thus, the list should be arranged in ascending order of importance; in the example above, FAMn would be given priority over any other adjacent surface families in the list.

Element groups, material properties and boundary conditions

In MULCAD the boundary conditions and properties are defined using the "Unspec. Bound. Cond." menu. In the Mesh Editor, the boundary conditions and properties are defined under the menu option "Output"->Bond. Conds".

The following sections explain how to define properties and boundary conditions for the STAR-CD interface in MULCAD. For boundary conditions generated in MED, the user simply needs to fill the appropriate fields in the GUI.

Element groups and ICTID

The translator creates groups of elements based on the name tagging found in the file ICEM CFD boundary condition file. A group is created for each family found in an unstructured grid file. The family names are used as group names.

Each group of elements with a distinct name gets a distinct ICTID number. The ICTID are written in the "ctable" of the .inp file where they are listed with the different group names, types and ICOLOR. The element file contains the ICTID number of each element.

The translator has 2 different options for setting the ICTID numbers:

The ICTIDs can be user defined in the boundary condition menu. There should be one ICTID number per ICEM family.
If no ICTID are defined by the user, they are set automatically in the ICEM output interface. In such case, the ICTIDs are numbered consecutively from the starting ITCID number. The starting ICTID number is set to 5 by default but can be change in the STAR-CD interface menu when launching the translator.

Material Property for STAR-CD

By default, all 3D elements are given the type FLUID (bctype=1). This can be modified to SOLID (bctype=2) in the boundary condition menu. The boundary condition type (bctype) is represented by an integer in the STAR-CD element file.

Boundary region number

Each boundary region for which a boundary condition is defined is represented by a list of shell elements in the STAR-CD boundary file. The boundary condition itself is written in the STAR-CD command file. The description of the boundary elements in the STAR-CD boundary file includes their connectivity, boundary region numbers and group names.

Defining boundary condition for STAR-CD

The following boundary conditions are supported by the translator. The boundary elements for which such conditions are defined, are written in the STAR-CD boundary file with their boundary region number. The properties of all the boundary regions are listed in the command file.

The following sections explain how to define boundary conditions for the STAR-CD interface in MULCAD. For boundary conditions generated in MED, the user simply needs to fill the appropriate fields in the GUI.

BAFFLE (bctype=3)

MULCAD field	Data
1. FLAG	Enter the string BAFFL
2. NR	Enter 1 for SLIP, 2 for NO-SLIP
3. VALUE	Enter 1 for ADIABATIC, 2 for FIXED, 3 for FLUX, 4 for CONDUCTIVE
4. X	If NO-SLIP, enter permeability coefficient ARES
5. Y	If NO-SLIP, enter permeability coefficient BRES
6. Z	If NO-SLIP, enter porosity POROS
8. A	If FIXED, specify temperature If FLUX, specify flux If CONDUCTIVE, specify resistance
9. B	If FIXED, specify resistance
12. ATTRIB	Enter the string TYPE

WALL (bctype=4)

MULCAD field	Data
1. FLAG	Enter the string WALL
2. NR	Enter 1 for SLIP, 2 for NO-SLIP
3. VALUE	Enter 1 for ADIABATIC, 2 for FIXED, 3 for FLUX, 4 for CONDUCTIVE
4. X	If NO-SLIP, enter U
5. Y	If NO-SLIP, enter V
6. Z	If NO-SLIP, enter W
7. SCALE	If NO-SLIP, enter w
8. A	If FIXED, specify temperature If FLUX, specify flux If CONDUCTIVE, specify resistance
9. B	If FIXED, specify resistance
12. ATTRIB	Enter the string TYPE

SYMMETRY PLANE(bctype=5)

MULCAD field	Data
1. FLAG	Enter the string SYMM
12. ATTRIB	Enter the string TYPE

INLET (bctype=6)

MULCAD field	Data
1. FLAG	Enter the string INLET
3. VALUE	Enter U
4. X	Enter V
5. Y	Enter W
6. Z	Enter w
7. SCALE	Enter Ke
8. A	Enter eps
9. B	Enter t
12. ATTRIB	Enter the string TYPE

OUTLET (bctype=7)

MULCAD field	Data
1. FLAG	Enter the string OUTLT
2. NR	Enter 1 for Split Flow or 2 for Fixed Flow Rate
3. VALUE	Enter the flow split or flow rate
12. ATTRIB	Enter the string TYPE

PRESSURE (bctype=8)

MULCAD field	Data
1. FLAG	Enter the string PRESS
2. NR	Enter 1 for PIEZO, 2 for STATIC
3. VALUE	Enter pressure
4. X	Enter 1 if environmental pressure
5. Y	Enter 1 if mean value
6. Z	Enter turbulent intensity
7. SCALE	Enter length scale
8. A	Enter temperature
12. ATTRIB	Enter the string TYPE

CYCLIC (bctype=9)

MULCAD field	Data
1. FLAG	Enter the string CYCLC
2. NR	Enter 1 for "integral", 2 for "arbitrary"
3. VALUE	If "arbitrary", enter x-offset
4. X	If "arbitrary", enter y-offset
5. Y	If "arbitrary", enter z-offset
12. ATTRIB	Enter the string TYPE

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