Pterasoftware

This release fixes the bug described in 12, which caused some users to experience zero division errors due to Numba's `fastmath` option.

Release Notes

I’m excited to announce the release of Ptera Software 2.0.0! In addition to improving our tool’s core mission of making flapping-wing flight research fast, easy, and open-source, this new version of Ptera Software incorporates several exciting new features!

Change List

Multiple-Airplane Simulations

Users can now simulate the unsteady aerodynamics of groups of flapping-wing vehicles. This feature has fascinating potential to further the study of avian formation flight! One side effect of this feature is that all solvers require users to input a list of Airplane objects, and unsteady solvers require a list of Movement objects. For simulations with only a single airplane, input lists with only one Airplane/Movement. Check out the unsteady_ring_vortex_lattice_method_solver_variable_formation.py example file for more details.

Performance Improvement

By refining Ptera Software’s use of JIT compilation, this version can complete our unsteady benchmark 1.29 times faster than the previous release!

Animate Method Uses WebP instead of GIF

To mitigate issues with large file sizes and low numbers of possible colors, this version has switched to using WebP file formats instead of GIF for the animate function. The PyPI WebP package was added as a dependency to provide this feature. As an added bonus, the animate feature now produces animations that play at a framerate corresponding to the real frequencies of the motion. Please read through the output script’s animate function for more details.

Force Coefficients instead of Pressures

Previously, the animate and draw functions allowed users to visualize the normal pressure on each wing panel. Unfortunately, this has led to some confusion regarding which direction is defined as normal on a moving wing. Furthermore, the pressures were defined in the geometry frame, which is generally a less revealing choice of axes when interested in forces and moments. To fix this, we’ve switched to allowing users to plot either the lift, drag or side force coefficients on each panel, all of which are defined in the wind frame. Please see the new parameter options for the animate and draw methods for more information.

Major Bug Fixes

Velocity due to Flapping

A significant bug in the unsteady solver’s flapping velocity methods has been corrected. The bug was a sign flip for calculating the apparent wind due to the aircraft’s motion and often caused pressures and forces opposite what was expected for moving geometry. Therefore, all users are recommended to update to this version to analyze moving geometry.

This release implements a hotfix to the bug in issue 9 . I also tested it beforehand, and it seems to resolve the problem.

This hotfix is an attempt at fixing the bug described in Issue 9. However, it is difficult to test this without publishing a release. Therefore, if this doesn't work, there will be a new hotfix soon to try again.

This release implements the following new features:

Features:
- I added a model for the evolving wake vortex core radii. This feature eliminates issues due to wake body interactions and is a significant step towards modeling hovering flight.

Performance:
- I optimized the aerodynamics functions use of Numba.
- I eliminated slow object copying by preallocating arrays to hold information about each time step's wake.
- I eliminated slow calls to numpy.vstack and numpy.hstack through preallocated arrays.
- With these changes, my laptop can now run a typical use case in 21 seconds!

Output:
- I overhauled the aesthetic of the animations, drawings, and result plots.
- The animation and drawing methods now automatically detect if a diverging or linear colormap should be used.
- The result plots now include markers, which things clearer when two lines are on top of each other.

Refactoring:
- I consolidated several similar methods to reduce code duplication.
- I split up several overly complicated methods.

Maintenance:
- I updated a significant number of the project's docstrings.
- I updated the readme to reflect the project's evolving goals.

Debugging:
- I fixed a major bug where symmetric wings weren't aligning at the root.
- Note: Finding and fixing this bug has significantly improved the stability of free-wake simulations. However, there seem to be a few more bugs that are causing issues. I intend to address this in future releases.

This hotfix fixed some formatting errors that led to a problematic README file and issue templates that GitHub couldn't read.