NS3D Interface

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The interface writes coordinate, topology, and boundary condition information in the NS3D input file format.

Creating the NS3D input file

The translator writes the NS3D input file using the domain file(s), the boundary condition file(boco) and, if structured, the topology file (topo_mulcad_out) generated in ICEM. The structured domains can be created by PADAMM, P-CUBE or the HEXA-Mesher (Multiblock) and the unstructured domains can be generated in PADAMM, the HEXA-Mesher (Unstructured) or the TETRA-Mesher.

To create the NS3D input file, select the translator "NS3D" in the "Output" menu of the ICEM CFD/CAE Manager. After selecting "Write input" from the same menu, specify the following options for the NS3D interface:

• specify if the mesh is structured or unstructured
• give the name of the boundary conditions file
  (default is "configuration/parts_mesh/mesh/boco")
• if structured domain(s), give the name of the topology file
  (default is "configuration/topology/topo_mulcad_out")
• if unstructured domain, give the name of the unstructured domain file
  (default is "configuration/parts_mesh/domains/struct_merge")
• give the name of NS3D input file
  (default is "configuration/parts_mesh/transfer/ns3d.grid")

The interface generates the NS3D input file located in the Transfer shell. A shell window may be opened in this directory by selecting the menu items "Utility" and "Transfer Shell".

Defining boundary conditions for NS3D

The boundary conditions must be defined on surfaces for a 3D model and on edges for a 2D model. They are defined using the "Unspec. Bound. Cond." menu in MULCAD or the "General bound. cond." menu in the DDN-Mesher Interface. Please refer to the General Remarks section for more details.

Identical, symmetry or periodic plane/edge:

To specify an identical, periodic or symmetry plane (or edge in 2D), simply assign the keyword IDENT, PERIO or SYMM to the selected area.

        MULCAD          DDN-Mesher      P-CUBE
        ------          ----------      ------
        1.FLAG          1.string1       NAME field     Enter IDENT, PERIO or SYMM

Exit, inlet or wall:

To specify an exit, inlet or wall, simply assign the keyword EXIT, INLET or WALL to the selected plane (or edge if 2D). The exit, inlet or wall number are set to one by default, but can be set to any integer from 1 to 999.

        MULCAD          DDN-Mesher      P-CUBE
        ------          ----------      ------
        1.FLAG          1.string1       NAME field     Enter EXIT, INLET or WALL
	2.NR            3.integer       ID # icon      Enter the number

Notes:

• The boundary condition IDENT is set automatically on the block interfaces of multiblocks structured grids.
• The character strings can be typed in lower or upper case.

Eligible element types

The interface supports linear and quadratic elements. The eligible types of elements are:

                 STRUCTURED                     UNSTRUCTURED 
            _____________________          ______________________

               2D          3D                 2D          3D
            _____________________          ______________________

Linear       QUAD_4      HEXA_8             QUAD_4      HEXA_8
                                            TRI_3       TETRA_4
						        PENTA_6

Quadratic    QUAD_8      HEXA_20            QUAD_8      HEXA_20
                                            TRI_6       TETRA_10
						        PENTA_18
            _____________________          ______________________

Note that for NS3D, the quadratic elements QUAD_8 and HEXA_20 are written from the QUAD_9 and HEXA_27 elements produced in ICEM.

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