Tutorial
A complete sample script to generate a grid is given below. This particular example is available under examples/BWB/runBWB.py.
# rst import (start)
import os
from pyhyp import pyHyp
# rst import (end)
baseDir = os.path.dirname(os.path.abspath(__file__))
surfaceFile = os.path.join(baseDir, "bwb.fmt")
volumeFile = os.path.join(baseDir, "bwb.cgns")
options = {
# ---------------------------
# Input Parameters
# ---------------------------
"inputFile": surfaceFile,
"unattachedEdgesAreSymmetry": True,
"outerFaceBC": "farfield",
"autoConnect": True,
"BC": {},
"families": "wall",
# ---------------------------
# Grid Parameters
# ---------------------------
"N": 81,
"s0": 4e-6,
"marchDist": 1100.0,
# ---------------------------
# Pseudo Grid Parameters
# ---------------------------
"ps0": -1.0,
"pGridRatio": -1.0,
"cMax": 2.5,
# ---------------------------
# Smoothing parameters
# ---------------------------
"epsE": 1.0,
"epsI": 2.0,
"theta": 3.0,
"volCoef": 0.25,
"volBlend": 0.0002,
"volSmoothIter": 150,
}
# rst object
hyp = pyHyp(options=options)
# rst run
hyp.run()
hyp.writeCGNS(volumeFile)
Each section of the example is now described.
import os
from pyhyp import pyHyp
This is the preferred way of importing the pyHyp module into python.
The options dictionary is used to provide all run-time options to pyHyp to control the generation of the grid. A description of each option and its general effect on the grid generation process is explained in Options.
The next line of code
hyp = pyHyp(options=options)
generates the pyHyp object.
Note
When exporting a surface mesh from ICEMCFD in plot3d format use the following options:
Formatted
Whole
Double
No IBLANK Array
Warning
It is essential that the normals of each of the surface patches point in the OUTWARD direction, i.e. the marching direction.
The next two lines perform the actual generation and write the resulting grid to a cgns file:
hyp.run()
hyp.writeCGNS(volumeFile)
The output of the run should look similar to the following:
#--------------------#
Total Nodes: 14105
Unique Nodes: 13457
Total Faces: 13376
#--------------------#
Normal orientation check ...
Normals are consistent!
Determining topology ...
Topology complete.
#--------------------#
Grid Ratio: 1.2532
#--------------------#
#-------------------------------------------------------------------------------------------------------------------#
# Grid | CPU | Sub | KSP | nAvg | Sl | Sensor | Sensor | Min | Min | deltaS | March | cMax | Ratio |
# Lvl | Time | Its | Its | | | Max | Min | Quality | Volume | | Distance | | kMax |
#-------------------------------------------------------------------------------------------------------------------#
2 0.1 2 11 0 0.055 1.00006 0.98387 0.38387 0.359E-10 0.314E-05 0.451E-05 0.0011 0.0000
3 0.2 2 11 0 0.064 1.00010 0.96703 0.35947 0.657E-10 0.493E-05 0.116E-04 0.0018 1.9184
4 0.3 1 11 0 0.067 1.00012 0.96111 0.35650 0.103E-09 0.618E-05 0.165E-04 0.0022 1.5882
5 0.4 2 11 0 0.074 1.00024 0.90864 0.35575 0.174E-09 0.787E-05 0.305E-04 0.0035 1.7282
6 0.4 1 11 0 0.076 1.00031 0.89199 0.35610 0.237E-09 0.987E-05 0.383E-04 0.0035 1.3561
7 0.5 1 11 0 0.079 1.00037 0.87508 0.35613 0.371E-09 0.124E-04 0.482E-04 0.0044 1.5634
8 0.5 2 11 0 0.084 1.00083 0.78268 0.35729 0.548E-09 0.155E-04 0.761E-04 0.0069 1.4708
9 0.6 1 11 0 0.087 1.00108 0.75129 0.36201 0.717E-09 0.194E-04 0.916E-04 0.0069 1.3003
10 0.6 1 11 0 0.089 1.00124 0.74002 0.36599 0.104E-08 0.243E-04 0.111E-03 0.0086 1.4222
< iterations skipped for brevity >
78 33.9 22 29 0 0.904 0.98475 0.97354 0.32556 0.347E+04 0.730E+01 0.562E+03 2.5000 1.2603
79 36.1 22 29 0 0.936 0.98435 0.97427 0.32565 0.688E+04 0.930E+01 0.708E+03 2.5000 1.2570
80 38.0 21 29 0 0.968 0.98388 0.97469 0.32573 0.138E+05 0.119E+02 0.885E+03 2.5000 1.2551
81 39.9 20 29 0 1.000 0.98341 0.97476 0.32579 0.276E+05 0.152E+02 0.110E+04 2.5000 1.2540
Several important parameters are displayed to inform the user of the solution progress. The most of important of which is the Min Quality column. This column displays the minimum quality of all the cells in the most recently computed layer of cells. For a valid mesh, these must be all greater than zero.