golfball is a Projectile Simulation including the "Drag Crisis" with selectable surface feature size. The simulation has its own 1976 Standard Atmosphere model to explore variation in performance with altitude relative to mean sea level.
Full documentation is on the GitHub Pages site for this repository.
To install the golfball model, you'll need a python installation with the PyPA/PyPI pip tool installed, as well as the make command line tool. If you don't want pip to install golfball's dependencies, use your Python package manager of choice (e.g. conda) to automatically install the following dependencies:
- ruamel.yaml
- pytables
- numpy
- scipy
- pandas
To install the golfball model for use in your python system, make sure you have the proper virtualenv or conda env active (if you don't know what those are, don't sweat it), and do the following:
$ git clone https://github.com/esba1ley/golfballor if you have ssh keys set up with GitHub:
$ git clone [email protected]:esba1ley/golfball.gitThen:
$ cd golfball
$ make installPip will automatically install any dependencies from the list above if you don't have them in your environment already.
This package installs two command line tools:
- gball: the simulation itself
- yaml2results: converts the YAML output of the sim into a Dakota results file
You can run gball as follows:
$ gball
and you'll have both the default input file and output file written to the local directory: projectile_inputs.yml and projectile_outputs.yml, respectively. All the parameters you can change for the simulation are specified in the input file, which if you edit that file you can run the sim again, and it will use the local file named 'projectile_inputs.yml'. If you copy and or re-name the input file, you can specify a different input file as follows (where we changed the launch angle to 10.0 degrees):
$ gball -i projectile_inputs_10deg.yml
The '--verbose' or '-v' option shows the configuration and the results in a nice formatted way for the user to see what was run and what the results were:
$ gball -i projectile_inputs_10deg.yml -v
Config Parameters
----------------
-- out_filename : projectile_outputs.yml
-- traj_filename : projectile_trajectory.h5
-- write_traj : False
Time Parameters
----------------
-- dt : 0.01
-- t_init : 0.0
-- t_stop : 20.0
Input Parameters
----------------
-- D : 0.04222
-- eD : 0.0125
-- g_LL : [0.0, 0.0, -9.81]
-- m : 0.0459
-- rho_scale : 1.0
-- wind : [0.0, 0.0, 0.0]
Initial State
----------------
-- angle : 10.0
-- pos_LL : [0.0, 0.0, 0.0]
-- vel_mag : 70.0
Quantities of Interest (QoI):
-----------------------------
-- Distance Travelled: 103.706223 m
-- Max Height: 5.672940 m
-- time @ impact: 2.130000 s
If you ever need help with the command line options, just use the '--help' or '-h' option:
$ gball --help
usage: golfball [-h] [--verbose] [--in_filename [IN_FILENAME]] [--t_init T_INIT]
[--t_stop T_STOP] [--dt DT] [--pos_LL POS_LL POS_LL POS_LL]
[--vel_mag VEL_MAG] [--angle ANGLE] [--m M] [--D D] [--eD ED] [--g_LL G_LL]
[--rho_scale RHO_SCALE] [--wind WIND WIND WIND]
[--out_filename [OUT_FILENAME]] [--write_traj] [--traj_filename TRAJ_FILENAME]
optional arguments:
-h, --help show this help message and exit
--verbose, -v print inputs and outputs to STDOUT
--in_filename [IN_FILENAME], -i [IN_FILENAME]
filename of YAML w/ inputs (default: projectile_inputs.yml)
--t_init T_INIT initial sim time. default: specified by input file)
--t_stop T_STOP simulation max time. default: specified by input file
--dt DT simulation time step. default: specified by input file
--pos_LL POS_LL POS_LL POS_LL
initial position vector in Local Level frame. default: specified by
input file
--vel_mag VEL_MAG initial velocity magnitude. default: specified by input file
--angle ANGLE launch angle above horizontal. default: specified by input file
--m M, -m M golf ball mass. default: specified by input file
--D D, -D D golf ball diameter. default: specified by input file
--eD ED dimple size ratio. default: specified by input file
--g_LL G_LL gravity vector in Local Level frame. default: specified by input file
--rho_scale RHO_SCALE
density scale multiplier. default: specified by input file
--wind WIND WIND WIND
constant wind vector in Local Level. default: specified by input file
--out_filename [OUT_FILENAME], -o [OUT_FILENAME]
name of YAML output file for QoI. default: specified by input file
--write_traj flag to write trajectory file. default: False
--traj_filename TRAJ_FILENAME
trajectory output filename. default: specified by input file
In your Python environment of choice, after installation as described above you can run your first sim very easily via the main function, passing it a list of arguments you'd have used at the command line:
from golfball.sim import Sim
import pprint
pp = pprint.PrettyPrinter(indent=2)
gb_sim = Sim()
pp.pprint(gb_sim.inputs)
gb_sim.run()
pp.pprint(gb_sim.qoi)Should output
{ 'config': { 'out_filename': 'projectile_outputs.yml',
'traj_filename': 'projectile_trajectory.h5',
'write_traj': False},
'params': { 'D': 0.04222,
'eD': 0.0125,
'g_LL': [0.0, 0.0, -9.81],
'm': 0.0459,
'rho_scale': 1.0,
'wind': [0.0, 0.0, 0.0]},
'state': {'angle': 38.0, 'pos_LL': [0.0, 0.0, 0.0], 'vel_mag': 70.0},
'time': {'dt': 0.01, 't_init': 0.0, 't_stop': 20.0}}
{ 'max_height': 50.08844542014751,
'max_range': 185.2417438617364,
'time_of_flight': 6.28}
where the assigned variable output is a dictionary containing the Quantities of Interest (QoI) with the following keys:
{ 'max_height': 50.08844542014751,
'max_range': 185.2417438617364,
'time_of_flight': 6.28}
note that if you don't already have it, this example also writes a default inputs file 'projectile_inputs.yml' and captures the outputs in the default outputs file 'projectile_outputs.yml'. The user can specify these files as command line arguments passed to main(). If no input file is specified, the default parameters will be used to create a new 'projectile_inputs.yml' if one doesn't already exist, or use the existing file of that name if it does.
See documentation for more detailed examples and features.
- Documentation: https://esba1ley.github.io/golfball/_build/html/index.html
- Issues: https://github.com/esba1ley/golfball/issues
Copyright Erik S. Bailey, all rights reserved. See the bundled LICENSE file for more details.