cpslicer

# Cp Slicer

Included with the release of OpenVSP 3.13.0, the CpSlicer generates the 2D Cp distribution at a specified planar cut defined parallel to the XY, YZ, or XZ plane. The CpSlicer uses the binary *.adb file generated by running VSPAERO to calculate the Cp distribution at each cut specified in the *.cuts file. Below is a basic *.cuts file, where 3 cuts or slices have been defined perpendicular to the Y axis.

3
y 1.960784
y 3.921569
y 7.843137


The CpSlicer will generate results and output them to a *.slc file for each specified cut and flow condition case. An example of a *.slc file can be seen below. If VSPAERO is run using the vortex lattice method, the forth column of the *.slc will list dCp. If the panel method is used, Cp will be listed.

BLOCK Cut_1_at_Y:_1.960784
Case: 1 ... Mach: 0.300000 ... Alpha: 1.000000 ... Beta: 0.000000 ...     Case: 1 ...
x          y          z         dCp
4.4785     1.9608     0.0000    -0.0018
4.4737     1.9608     0.0000    -0.0019
4.4146     1.9608     0.0000    -0.0034
4.4077     1.9608     0.0000    -0.0036
4.3227     1.9608     0.0000    -0.0059
4.3131     1.9608     0.0000    -0.0061
4.1935     1.9608     0.0000    -0.0081
4.1802     1.9608     0.0000    -0.0083
4.0167     1.9608     0.0000    -0.0104
3.9993     1.9608     0.0000    -0.0106
3.7844     1.9608     0.0000    -0.0130
3.7627     1.9608     0.0000    -0.0133
3.4946     1.9608     0.0000    -0.0161
3.4693     1.9608     0.0000    -0.0164
3.1556     1.9608     0.0000    -0.0198
3.1281     1.9608     0.0000    -0.0202
2.7876     1.9608     0.0000    -0.0243
2.7600     1.9608     0.0000    -0.0249
2.4192     1.9608     0.0000    -0.0300
2.3937     1.9608     0.0000    -0.0307
2.0792     1.9608     0.0000    -0.0374
2.0574     1.9608     0.0000    -0.0384
1.7883     1.9608     0.0000    -0.0474
1.7710     1.9608     0.0000    -0.0488
1.5557     1.9608     0.0000    -0.0619
1.5425     1.9608     0.0000    -0.0643
1.3797     1.9608     0.0000    -0.0867
1.3703     1.9608     0.0000    -0.0920
1.2533     1.9608     0.0000    -0.1419
1.2470     1.9608     0.0000    -0.1518
1.1687     1.9608     0.0000    -0.2511
1.1660     1.9608     0.0000    -0.2601
1.1321     1.9608     0.0000    -0.3968


## Command Line and API

To run the vspslicer application through the command line, VSPAERO must first be run to generate a *.adb file. For information regarding how to run VSPAERO through the command line, see VSPAERO from Command Prompt Window. Note, a DegenGeom and *.vspaero Setup file must be created before running VSPAERO. After VSPAERO has been run, a *.adb file will be available for the CpSlicer. The only additional file needed is the *.cuts file, which must be named with the following convention: “'ModelName'_DegenGeom.cuts”. With the command prompt directory set to the directory containing all required files with the vspslicer executable, simply enter “vspslicer 'ModelName'_DegenGeom” to generate a *.slc file. An example command line output can be seen below.

C:\Users\JustinG\Desktop\OpenVSP-3.13.3-win32>vspslicer Unnamed_DegenGeom
NumberOfNodes:  204
NumberOfTris:   320
Sref:           45.000000
Cref:           2.500000
Bref:           18.000000
Xcg:            2.937580
Ycg:            0.000000
Zcg:            0.000000
Wing: 1 ... WingGeom
Wing: 2 ... WingGeom
Xmin, Xmax: 0.000000, 6.196152
Ymin, Ymax: -9.000000, 9.000000
Zmin, Zmax: 0.000000, 0.000000
NumberOfPropulsionElements: 0
NumberOfMeshLevels: 2
Number of course nodes for level: 1 is: 204
Number of course edges for level: 1 is: 372
NumberOfControlSurfaces: 0
Finding tri edges...
Number of nodes: 204
Number of tris: 320
Number of edges is: 522
Note... mesh may not be closed!
CutType: y ... Value: 1.960784
CutType: y ... Value: 3.921569
CutType: y ... Value: 7.843137


To run the CpSlicer through the OpenVSP API or AngelScript interface, the CpSlicer analysis is available. For an example of this, see CpSlicer.vspscript in the scripts folder.

## VSPAERO GUI

The CpSlicer was incorporated into the VSPAERO GUI in OpenVSP v3.14.0 on the Advanced tab under “Cp Slicer”. Initially, the Activate Cp Slicer toggle will be disabled, but can be selected once slices have been defined. This is done by simply selecting Add Slice and modifying the slice type and position. The Show Cut toggle can be used to verify that the slice intersects the geometry as desired. The Activate Cp Slicer toggle can then be selected to automatically create a *.cuts file and generate CpSlicer results once VSPAERO is run by clicking Launch Solver. If VSPAERO has already been run, the Slice Latest *.adb File button will execute the CpSlicer for the latest run case.

### Results Manager

Results from the CpSlicer can be viewed on the Cp Slice tab of the VSPAERO Results Manager. The top left browser under “Slice” lists each item in the *.cuts file. Under “X-Axis Plotting”, the coordinate axis to plot for each slice type can be specified. The Cp Slice graph will display dCp or Cp vs. axis position (x, y, z, or multiple). The VSPAERO flow conditions are identified as unique run cases under “Flow Condition”. The legend lists each plotted cut and case. The “Actions” section is available to set the axis limits, invert the Y axis (multiplies dCp/Cp by -1), or disable plotting of lines.

This page was created and edited by: — Justin Gravett 2017/12/12 10:00