CFD Utilities Files

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   program redistribute_xy

!  Purpose:
!
!     Read an (x,y) line segment (2 columns, 2 or more points), assumed to be
!     geometric, and impose a specified number of points redistributed in terms
!     of arc length with specified first and last spacings. One-sided stretching
!     is also an option (spacing specified at one end or the other only).
!     Curvature-based redistribution is also an option now.
!
!  Motivation:
!
!     A capsule defined by a generatrix with corners that need to be captured
!     as well as possible needs those vertices well defined enough for splines
!     not to misbehave there.  Simply adding lots of points either side of a
!     vertex on its own may also misbehave because the curvature-based redis-
!     tribution in terms of arc length has more trouble converging as the number
!     of data points goes up.  This utility is intended to enable clustering of
!     the defining point towards a vertex with more moderate numbers of points.
!     A thruster nozzle profile prompted the curvature-based option.
!
!  Method:
!
!     Read the line segment and calculate its arc lengths.  Prompt for first
!     [and last?] desired arc lengths along with the output number of points.
!     A call to the expdis5 or vinokur utility gives the 1-sided or 2-sided
!     redistributed arc lengths from which the redistributed (x,y)s are
!     interpolated via local spline interpolation.  In the case of curvature-
!     based redistribution, curvdis2 performs that on [normalized] arc lengths
!     before doing the same sort of spline interpolation of x and y vs. s.
!
!  History:
!
!     02/03/2021  D.A.Saunders  Initial implementation to help CAPSULE_GRID
!                               (2-sided stretching only).
!     02/10/2021    "      "    Added the 1-sided stretching option that
!                               should have been there from the start.
!     03/03/2021    "      "    Added curvature-based redistribution option.
!     03/-5/2021    "      "    Arranged for suppressing or logging the
!                               (voluminous) diagnostic output from curvdis.
!     06/14/2021    "      "    If 1-sided clustering is at the last point,
!                               we want the output to be in the same order.
!     01/20/2022    "      "    Display the first and last arc length intervals.
!
!  Author:  David Saunders, AMA, Inc. at NASA Ames Research Center, CA.
!
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