v2.0.0

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.