CFD Utilities Files

SORT_SURFACE_SLICE Description:

This utility reads a dataset resulting from Tecplot's option to slice a
surface dataset defined by a plane.  The dataset has been saved as a single
zone of nodes and 2-point line segment pointers.  Plotting the points as
symbols may not be appropriate: a continuous curve is commonly desired, and
sorting by x, y, or z may be all that is needed.  Plotting against arc
length along the curve may also be desirable, so the option to add
cumulative arc length as an additional variable is also provided.

Originally, the program just treated the common case where sorting the
nodes in x, y, or z suffices to produce a single meaningful continuous
curve.  This version retains that option but can also allow for more than
one contiguous curve in the slice, as in the case of a cut through a
fuselage that also encounters the outboard portion of a swept wing.  Each
such segment appears as a distinct zone in the output file and may have
arc lengths added.  This option makes use of the 2-point line segment
pointers accompanying the slice coordinates.

Further, a specialized option is provided for the common requirement of
plotting surface quantities versus run length from the stagnation point of
a hypersonic flow solution (capsule centerline, or possibly near the wing
leading edge of a wing section slice).  If a single contiguous curve is
found, and a flow variable name starts with p or P, and insertion of arc
lengths has been requested, then the peak pressure point along the curve is
taken to be the stag. pt., and arc lengths are adjusted to increase in both
directions away from it.  This form is appended as a second output zone,
preserving the initial ordered slice zone in case the stag. pt. option is
not intended, since no extra prompts have been added.

Sample input dataset (POINT order, single zone, 1 variable name per line):

   TITLE     = "A"
   VARIABLES = "x [m]"
   "y [m]"
   "z [m]"
   "pw [Pa]"
   "qw [W/m^2]"
   ZONE T="Slc: Z=0"
    STRANDID=0, SOLUTIONTIME=0
    Nodes=118, Elements=109, ZONETYPE=FELineSeg
    DATAPACKING=POINT
    DT=(DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE )
    1.584258E-02 3.505522E-01 0.000000E+00 1.358903E+03 1.643338E+05
    1.646541E-02 3.586402E-01 1.969463E-19 1.358848E+03 1.643071E+05
     :            :            :            :            :
    1.250000E+01 1.000000E+01 4.147692E-18 1.009208E+03 4.999492E+04
    2 1
    2 3
    3 4
    6 5
    : :
    117 118

Corresponding output (single segment case with arc lengths inserted):

   TITLE     = "A"
   VARIABLES = "x [m]"
   "y [m]"
   "z [m]"
   "pw [Pa]"
   "qw [W/m^2]"
   "s [m]"
   ZONE T="Slc: Z=0"
    STRANDID=0, SOLUTIONTIME=0
    I=118, J=1, K=1, ZONETYPE=Ordered
    DATAPACKING=POINT
    DT=(DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE )
    1.58425E-02 3.50552E-01 0.00000E+00 1.35890E+03 1.64333E+05 0.0000E+00
    1.64654E-02 3.58640E-01 1.96946E-19 1.35884E+03 1.64307E+05 1.2345E-02
     :           :           :           :           :           :

   [ZONE T="Slc: Z=0, Stag. Pt. Run Length"
    STRANDID=0, SOLUTIONTIME=0
    I=118, J=1, K=1, ZONETYPE=Ordered
    DATAPACKING=POINT
    DT=(DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE )
    1.64654E-02 3.58640E-01 1.96946E-19 1.35884E+03 1.64307E+04 1.2345E+00
    1.58425E-02 3.50552E-01 0.00000E+00 1.35890E+03 1.64333E+04 1.2340E+00
     :           :           :           :           :           :
    1.58425E-02 3.50552E-01 0.00000E+00 7.65432E+03 1.64333E+05 0.0000E+00
     :           :           :           :           :           :
    1.58425E-02 3.50552E-01 0.00000E+00 1.35890E+03 1.64333E+04 1.2340E+00
    1.64654E-02 3.58640E-01 1.96946E-19 1.35884E+03 1.64307E+04 1.2345E+00]

I/O Strategy:

   Keep the parsing that would elsewhere be de rigeur to a minimum.
   This is a file written consistently by Tecplot, after all.
   Scan the header lines as strings until a purely numeric string is found.
   Rewind and reread the header lines as an array. Find the line containing
   NODES (after upcasing) and adjust as shown in the sample if simple sort-
   ing is specified.  If arc length is to be appended as an extra column,
   insert its name appropriately during writing of the output header lines.
   Read the indicated number of points, sort them as specified, and write
   them in the desired order, possibly appending an arc length to each
   line.  If the 2-point line segments are to be pieced together as one or
   more contiguous curves, a more awkward output strategy is required, but
   existing utility CUTORDER does the hard part after extension to one or
   more functions.

History:

   07/30/10  D.A.S.  Initial implementation of useful functionality
                     prompted by John Theisinger's axisymmetric/3-D
                     aero-heating correlation study.  Sorting should
                     suffice for simple geometries, but the 2-point
                     line segments should be pieced together properly
                     for general cases where multiple curve segments
                     should be written as separate zones.
   08/13/10    "     Completed it with the option to process the
                     2-point line segment information properly.
   08/19/10    "     Data lines from BLAYER exceed 512 characters,
                     so the apparent number of variables was wrong.
   08/20/10    "     Plotting versus run length from stagnation point
                     is desirable enough that it has been added as a
                     somewhat specialized option for cases that find
                     one contiguous curve and have a flow variable
                     starting with p or P (since peak pressure is
                     taken to be at the stag. pt.).
   08/23/10    "     A slice that happens to be a closed curve and
                     can start/end anywhere needs special treatment
                     for the stag. pt. run-length option.  We assume
                     that the stag. pt. is on y = 0, locate the
                     aft-most point with y closest to 0, and shift
                     the data circularly to make that point index 1,
                     then proceed as for an open single curve.  Also,
                     blunt bodies don't suit positive arc lengths on
                     the lee side, so make those negative, and allow
                     for the common case of an upside-down capsule
                     by making the shorter of the two run lengths use
                     negative arc lengths if aspect ratio < 1.5.
   09/28/10    "     Slices from layouts with text boxes turn out to
                     include the text boxes before the zone info., so
                     inserting the arc length variable name had to be
                     done more carefully.
   10/06/10    "     Last_var_line wasn't being set if a pressure
                     variable was not present.
Author:

   David Saunders, ELORET Corporation/NASA Ames Research Center, CA