Which method does gyGeo uses to create final geometry

[Mohsin-Bashir]

Hi i was doing Multidisciplinary Design Optimization using Dafoam https://dafoam.github.io/mydoc_get_started_faq.html#can-i-get-the-optimized-geometry-in-a-cad-format. After we have obtained optimized mesh, how does pyGeo use FFD volume with initial geometry to create final optimized CAD geometry.
After studying the https://github.com/mdolab/pygeo/blob/main/pygeo/pyGeo.py and dvgeo.py files, what i understand is dvgeometry maps the ffd design variables information to initial geometry and then uses the same relationship to find the final geometry given the ffd design variables. Am i right? please guide me, if anyone have information about it.

[hntter]

hi, have you solved your problem?

[Mohsin-Bashir]

no

[lamkina]

Two main things I want to clarify:

1. pyGeo doesn't inherently store CAD geometry. Discrete mesh points are projected to a B-spline volume to invert the discrete cartesian coordinates to parametric coordinates of the volume.
2. As the B-spline volume (FFD) is deformed, we query the parametric coordinates to get the new discrete mesh coordinates.

In that sense, only two things are stored in pyGeo:

1. The surface mesh coordinates
2. The design variables that map to movement of the B-spline volume control points

If you want to get the optimal surface mesh, you supply the optimal design variables to DVGeometry and access the surface mesh coordinates or write them to a Tecplot file. You can also access the underlying deformed BSpline volume that is stored in DVGeometry as a pySpline object.

The lack of underlying CAD is a feature of pyGeo because most times we only work with discrete mesh representations of the geometry.