This will copy all of the files into a newly created work/ folder. Follow
the instructions below by entering that work/ folder; the purpose is that
you can easily delete the work/ folder and restart the tutorial at any
time.
The geometry used for this shape is a capped cylinder with four fins and 9216
faces and seven components. The surface triangulation, arrow.tri`, is
shown below.
Figure 5.1 Simple bullet shape triangulation with four fins¶
The files in this folder are listed below with a short description. In this
case, the run matrix is defined within the pyFun.json file.
arrow-far.xml: (Not used) XML files used to define larger components
To get started, make sure that the $PYCART/bin folder is part of your
path and $PYCART is listed in the environment variable PYTHONPATH. It is
a good idea to put these in your startup file or create a module. For a BASH
environment, the following commands set up the environment for using pyCart
assuming that $HOME/pycart is where pyCart was installed.
Assuming the present working directory is in this demo folder, i.e.
$PYCART/examples/pycart/01_bullet, a good first test command is the
following, which checks the status of each case in the matrix.
Here pyFun has read the default master file name, pyFun.json and determined
that this is a setup with four cases. The run matrix has at least three input
variables, which are Mach number, angle of attack, and sideslip, although the
user can’t tell yet whether or not there are more input variables that don’t
affect the parametric folder names.
As it turns out, this is a viscous example, so we should expect Reynolds number
per inch and freestream static temperature to be inputs. It is permitted in
pyFun not to specify these inputs and just keep a constant value inherited from
the fun3d.nml namelist, but it would be unusual to have varying Mach
numbers and a constant freestream state. If we look at the final section in
pyFun.json, we see that Reynolds number and temperature are indeed
variables.
// Run matrix description"RunMatrix":{// File and variable list"File":"","Keys":["mach","alpha","beta","Re","T","config","Label"],// Modify one definition"Definitions":{"mach":{"Format":"%.2f"}},// Group settings"GroupMesh":false,// Label universal"Label":"","config":"arrow",// Local values"mach":[0.8,0.8,0.84,1.2],"alpha":[0.0,2.0,0.0,0.0],"beta":[0.0,0.0,0.0,0.0],"Re":[1e3,1e3,1e4,1e4],"T":[478,478,478,478]}
The second line, Keys, lists the five input variables we have discussed above
and two additional input variables used for bookkeeping. Each of these
variables has a standard name, so pyFun provides a default definition and
interpretation. However, it is possible to modify any aspect of a variable’s
behavior in the Definitions section.
Here we have modified the mach definition so that pyFun explicitly includes
exactly two digits after the decimal place in the folder name (otherwise we may
have difficulty with the Mach 0.84 case). There are many more capabilities of
this Definitions section. Some of them are discussed in other examples, and
the complete guide can be found in the “RunMatrix” section of the JSON
guide.
In this case, we have decided to specify the values of the variables within the
JSON file. We can specify a list with one value for each case, as in "mach":[0.8,0.8,0.84,1.2] or a constant value that applies to all cases as in
"config":"arrow".
To actually run a case, specifically the first case, run the following command.
It will show some status updates as it runs, but this may take a respectable
amount of time (about 7.5 CPU hours) to demonstrate a semi-realistic case. It
can be aborted with a Ctrl-C command if desired.
The arrow/m0.80a0.0b0.0 folder itself contains the hallmark files of a
FUN3D run with a project prefix of arrow (which is set within
pyFun.json or fun3d.nml) with a few additional files used by pyFun to
keep track of status.
