CFD Utilities Files

Program tri_to_tri description:

   Interpolate one unstructured surface flow solution to another in 3-space.
This is an adaptation of the earlier TRI_TO_QUAD, replacing the structured
target surface grid with a surface triangulation.  Both assume that the
input dataset is a single-zone surface triangulation.  Here, the target (and
hence output) triangulation may contain one or more zones.

Input Tecplot data format (original, vertex-centered):

   VARIABLES = "X", "Y", "Z", "TEMP", "PRESS", "CP", "MACHE", "ASOUNDE", ...
   ZONE N=96000, E=32000, F=FEPOINT, ET=TRIANGLE
   0.000000  0.000000 0.000000 2838.386719 51330.925781 1.552663 0.609412 ...
   0.000883 -0.007150 0.113643 2838.386719 51330.925781 1.552663 0.609412 ...
   0.000883  0.000000 0.113868 2838.386719 51330.925781 1.552663 0.609412 ...
   ::::::::::::::::
   ::::::::::::::::
   4.882953  0.000000 0.011285 950.867676 16.506409 -0.001166 5.062649 ...
   1 2 3
   4 5 6
   7 8 9
   10 11 12
   ::::::::
   ::::::::
   95992 95993 95994
   95995 95996 95997
   95998 95999 96000

Alternative cell-centered Tecplot input format (DPLR overset grid tools):

   TITLE     = ""
   VARIABLES = "x"
   "y"
   "z"
   "p"
   "Chm"
   "h"
   "qw"
   "Re_c"
   ZONE T="ZONE 001"
    STRANDID=0, SOLUTIONTIME=0
    Nodes=9367, Elements=18438, ZONETYPE=FETriangle
    DATAPACKING=BLOCK
    VARLOCATION=([4-8]=CELLCENTERED)
    FACENEIGHBORCONNECTIONS=55014
    FACENEIGHBORMODE=LOCALONETOONE
    FEFACENEIGHBORSCOMPLETE=YES
    DT=(SINGLE SINGLE SINGLE SINGLE SINGLE SINGLE SINGLE SINGLE )
    3.756540120E-01 3.601163924E-01 3.451932967E-01 3.309260905E-01  ...
   ::::::::::::::::

Control file format (standard input):

   TRI_TO_TRI control file
   xxxx.xxx        ! Surface triangulation and flow solution (Tecplot format)
   1               ! 1 => vertex-centered/Tecplot; 2 => cell-centered/Tecplot
   xxxx.xxx        ! Target grid (Tecplot multizone surface triangulation)
   T               ! T|F = formatted|unformatted
   xxxx.xxx        ! Output file (Tecplot multizone surface triangulation)
   T               ! T|F = formatted|unformatted
   0.0001          ! Distance tolerance for target pt. inside solution grid
  [7.890     0.    ! Optional X & F; if x > X, set finterp(:) = F]

Method:

   >  The surface triangulation is read as a single zone and converted to an
      ADT (Alternating Digital Tree) for search purposes.  If the function
      values are cell-centered, they are interpolated to the cell vertices
      first.  No unique best interpolation method exists.  The area-weighted
      averaging used here suffices for typical triangulations.
   >  Target zones are processed in order (read and written as needed).
   >  For each target point, the ADT search locates the nearest point on the
      surface triangulation (never outside it).  The function values can then
      be interpolated with the indicated trilinear coefficients.
   >  Optionally, target points beyond the indicated X will be set to the
      indicated F (probably zero, as for radiation on an aft body).

History:

   03/07/05  DAS  Initial TRI_TO_QUAD for vertex-centered function data.
   08/29/08   "   Added optional X and F to deal with radiative heating
                  that goes to zero beyond some X for CEV.
   03/15/10   "   Provided for DPLR/Overset-related triangulated input data
                  (type 2, cell-centered Tecplot format).
   08/08/13   "   All ADT variants are in one module now with generic
                  build_adt and search_adt interfaces.
   07/03/14   "   TRI_TO_TRI adapted from TRI_TO_QUAD.
   04/21/17   "   The tri_area(:) array name clashed with a callable utility
                  added subsequently to triangulation_io.f90.  It has been
                  renamed as triang_area(:).
   07/20/18   "   Hemispherical integration of radiance data involves multi-
                  zone triangulations.  Interpolation of such surface data
                  to a different triangulation is now an option following
                  an extension within triangulation_io that concatenates
                  all zones as a single zone within new header fields, for
                  rapid searching via the ADT scheme, which builds all cells
                  of all zones into its search tree rather than treating one
                  zone at a time.
   05/03/22   "   One glitch following triangulation_io extensions.


Author:  David Saunders, ERC, Inc./NASA Ames Research Center, CA
              Later with AMA, Inc. at ARC.