Authors: Stuart E. Rogers, Steven M. Nash, Pieter G. Buning
The MINTERP program interpolates data from single- or multiple-zone PLOT3D grid and solution/function files, or just grid files alone. The interpolation is performed on points defined to be the intersection of a cutting-plane and surface subsets of the input grid(s). If a solution file is provided, the output will be Cp values; if the input is a PLOT3D function file, this function will be interpolated.
The cutting-plane can be specified as either a constant x-, y-, or z-plane, or as an arbitrary plane as defined by 3 specified points.
By default the program uses l=1 grid subsets for the interpolation. The program can be directed to use any j, k, or l=constant surface subset using the -subs argument.
The interpolation is performed using modified version of the PLOT3D routine CON3LB.
The code will prompt for all necessary input, including input grid and solution files, the list of zones to be searched for intersections with the cutting planes. The input grid and solution (function) files must be 3D unformatted PLOT3D files. The following command-line arguments will alter the behavior of the code:
| Argument | Description |
|---|---|
| -j1 | use j=1 grid subsets |
| -jmax | use j=lmax grid subsets |
| -k1 | use k=1 grid subsets |
| -kmax | use k=lmax grid subsets |
| -l1 | use l=1 grid subsets (default) |
| -lmax | use l=lmax grid subsets |
| -nosort | skip the sorting step normally performed at the end |
| -subs | prompt for surface subsets for each zone |
| -output_normals | causes the formatted output file to include the components of the surface-normals. Each output record will contain x,y,z,D,F,xn,yn,zn. |
| -filter ifilter | Enables a filter which can remove certain datapoints based on the sign of the surface-normal component, based on the value of ifilter. For ifilter=1, write data with a positve surface-normal x-component. For ifilter=2, write data with a positve surface-normal y-component. For ifilter=3, write data with a positve surface-normal z-component. For ifilter=-1, write data with a negative surface-normal x-component. For ifilter=-2, write data with a negative surface-normal y-component. For ifilter=-3, write data with a negative surface-normal z-component. |
If the program is run to interpolate data on a grid and solution/function data, the output will be in an ASCII file with separate lines each containing data for x,y,z,D,F. The (x,y,z) coordinates define the intersection points between the cutting plane and the grid lines. F is the value of the interpolant (Cp or other function) at that point. D is the normalized distance from the first point. If desired, the x,y,z dimensions will be normalized by their (MAX-MIN) dimension (e.g. X = (X' - Xmin)/(Xmax - Xmin) ).
If the program is run with only grid data, the output file will be an unformatted PLOT3D grid file, containing the coordinates of the intersection between the cutting plane and the grid lines.
If the sorting is performed, the program will also remove any adjacent coincident points that it finds in the final sorted curve.