Definitions for CFD Applications

• Node Identifiers
• Node Header Definitions
• Variable Identifiers
• CFD Application Figures

This section describes the conventions to be used when using a common file for CFD applications. Consistent application of these conventions will assure that data will be accessible to a developing base of pre- and post- processing tools. For a picture representation of the following definitions see the figure representing the common file layout for .cfl files.

Node Identifiers

Zone Node Identifiers

Zone nodes are subnodes of the root node. A zone node is accessed and the header read through the following Fortran code fragment:

   CHARACTER*32 ZNAME
   INTEGER ZONE
   INTEGER STATUS, RSTATE, ZSTATE

   ! Note that the default sizes of IPARZ, FPARZ and CPARZ are used.

   INTEGER IPARZ(64)
   REAL    FPARZ(64)
   CHARACTER*80 CPARZ(2)

   ! RSTATE is the state of the root node returned by CFOPEN
   ! All zone nodes under the root node are named 'ZONE nnn'

   ZONE = zone number (1, 2, 3, etc.)
   WRITE (ZNAME, '(''ZONE '', I3)') ZONE
   CALL CFSNOD (STATUS, RSTATE, ZNAME, ZSTATE)
   CALL CFRNOD (STATUS, ZSTATE, IPARZ, FPARZ, CPARZ)

Boundary Node Identifiers

Boundary nodes are subnodes of a zone node. A boundary node is accessed through the following Fortran construct:

   CHARACTER*32 BNAME
   INTEGER BNDRY
   INTEGER STATUS, BSTATE, ZSTATE

   ! All boundary nodes for a given zone are stored under the zone
   ! node with a name of 'BNDRY n' where n is a number defined below.

   BNDRY = boundary (1=I1, 2=IMAX, 3=J1, 4=JMAX, 5=K1, 6=KMAX, 7=Chimera, 
                     >= 8=Unstructured)
   WRITE (BNAME, '(''BNDRY  '', I3)') BNDRY
   CALL CFSNOD (STATUS, ZSTATE, BNAME, BSTATE)

Interior Node Identifiers

Interior nodes are subnodes of a zone node (for 3-D unstructured grids only). An interior node is accessed through the following Fortran construct:

   CHARACTER*32 INAME
   INTEGER STATUS, ISTATE, ZSTATE

   ! An interior node for a given zone is stored under the zone
   ! node with the name 'INTERIOR'.

   INAME = 'INTERIOR'
   CALL CFSNOD (STATUS, ZSTATE, INAME, ISTATE)

Node Header Definitions

Note: All dimensional values stored in the common sections of the node headers must be in SI units. Data stored in the application-specific sections can be in any units the application desires.

Root Node Common Definitions

For unstructured grids, IPAR(1), IPAR(2), and IPAR(3) are not used. For a file containing both structured and unstructured zones, these parameters will have the correct values for the structured zones.

Wind-US Root Node Application Specific Data

Zone Node Header Common Definitions

Zone nodes can contain either structured or unstructured grids. These two types are distinguished based on IPAR(9) in the Zone Node Header. IPAR(9) will be 0 for structured grids and 1 or 2 for unstructured grids.

Structured Grid

Unstructured Grid

Wind-US Zonal Node Application Specific Data

Boundary Node Application Specific Data

Variable Identifiers

Geometry

The variables x, y, and z are located under the zone node for structured grids. For unstructured grids, x, y, and z for the boundary points are located under the zone node and x, y, and z for the interior points (3D) are located under the interior node. Note that IBLANK has labels encoded in it as follows: 1 = a normal point, −(label + 1) = a hole point, and +(label + 1) = a fringe point, where label is a positive number.

The following variables are applicable to unstructured grids only, and are located under the zone node for boundary surfaces and under the interior node for volumes. These variables describe the connectivity of the faces and/or edges.

The following variables are applicable to unstructured grids only, and are located under the the interior node. These variables describe the connectivity of the cells.

The following variables are applicable to unstructured grids only, and are located under the zone node. These variables describe collections of faces or surfaces. Currently, each surface must contain only a single face type (i.e., all triangles or all quads). Each of these variables are of size nsurfs = ipar(7).

General Flow Variables

Turbulence Variables

Chemistry Variables

Miscellaneous Variables

Wind-US Application Specific Variables

The following variables are used by Wind-US. For the new BC format, the "_n" variables are for node-centered grids, and the "_c" variables are for cell-centered grids. For cell vertex grids the size of the boundary is the number of points, and for cell-centered grids it is the number of faces.

For hybrid grids we have the following. When an unstructured cell-centered grid is coupled to a structured vertex-centered grid, the CellLoc_c data contains the structured bilinear factors used by the structured zone to interpolate the data to the unstructured face-centered location. For the other way, CellLoc_n contains the parameterized value of the structured point being coupled. The parameterization is based on the unstructured zone's face that is coupled to. This face number is stored in the CFace_n array. This is done since this face is not unique. Note this is not a problem for cell-centered unstructured-to-unstructured, since the parameterization is based on the unstructured face being coupled, and so there is no ambiguity. The follow code segments define the parameterization of the XYZ values into CellLoc_x.

The following takes the parameterization back to XYZ:

   !-----  Copy out the parameterization
           e123(1:3) = paramxyz(n,1:3)

   !-----  Calculate the coordinate vectors
           if ( VrtcsPerBndryFace >= 4 .and. facep(4,n) > 0 ) then
   !-----    Quad face
             v123(1,1:3) = VrtxXyz(facep(3,n),1:3) - VrtxXyz(facep(1,n),1:3)
             v123(2,1:3) = VrtxXyz(facep(4,n),1:3) - VrtxXyz(facep(2,n),1:3)
           else
   !-----    Tri face
             v123(1,1:3) = VrtxXyz(facep(2,n),1:3) - VrtxXyz(facep(1,n),1:3)
             v123(2,1:3) = VrtxXyz(facep(3,n),1:3) - VrtxXyz(facep(1,n),1:3)
           end if
           norm(1)   = (v123(1,2)*v123(2,3) - v123(2,2)*v123(1,3))
           norm(2)   = (v123(1,3)*v123(2,1) - v123(2,3)*v123(1,1))
           norm(3)   = (v123(1,1)*v123(2,2) - v123(2,1)*v123(1,2))
           v123(3,:) = norm / sqrt(sum(norm**2)) * sqrt(sum(v123(1,:)**2))

   !-----  Calculate the xyz cell center
           xyz(n,1) = VrtxXyz(facep(1,n),1) + sum(e123*v123(:,1))
           xyz(n,2) = VrtxXyz(facep(1,n),2) + sum(e123*v123(:,2))
           xyz(n,3) = VrtxXyz(facep(1,n),3) + sum(e123*v123(:,3))

The following parameterizes XYZ based on the input face:

   !-----  Setup the equations
           if ( VrtcsPerBndryFace >= 4 .and. facep(4) > 0 ) then
   !-----    Quad face
             v123(1,1:3) = VrtxXyz(1:3,facep(3)) - VrtxXyz(1:3,facep(1))
             v123(2,1:3) = VrtxXyz(1:3,facep(4)) - VrtxXyz(1:3,facep(2))
           else
   !-----    Tri face
             v123(1,1:3) = VrtxXyz(1:3,facep(2)) - VrtxXyz(1:3,facep(1))
             v123(2,1:3) = VrtxXyz(1:3,facep(3)) - VrtxXyz(1:3,facep(1))
           end if
           norm(1)   = (v123(1,2)*v123(2,3) - v123(2,2)*v123(1,3))
           norm(2)   = (v123(1,3)*v123(2,1) - v123(2,3)*v123(1,1))
           norm(3)   = (v123(1,1)*v123(2,2) - v123(2,1)*v123(1,2))
           v123(3,:) = norm / sqrt(sum(norm**2)) * sqrt(sum(v123(1,:)**2))
           b123 = xyzc - xyz(:,facep(1))

   !-----  Use Cramer's rule to solve the equations Ax = B
           call bg_ggutil_linsolve3x3_f ( status, v123, b123, e123 )
           if (status /= 0 ) e123 = 0

CFD Application Figures

Common File Layout for .cfl Files

Common File Layout for .cgd Files (Old BC Format)