Vaggelis Papoutsis authored Jul 19, 2023 and Andrew Heather committed Dec 18, 2023

- advectionDiffusion is frequently used within optimisation loops since
  it is differentiable. In shape optimisation, the re-computation of
  mesh distances is performed at the very beginning of a new
  optimisation cycle, due to inheriting from MeshObject. If the mesh
  quality is poor enough, the advectionDiffusion PDE might diverge and
  crash the run, before the problematic mesh is written to files for
  inspection. The default behaviour now is to check the mesh before
  solving the advectionDiffusion PDE and write the mesh points if some
  mesh check fails.
- fvOptions can now be included in advectionDiffusion (necessary for
  topology optimisation of turbulent flows for models that include the
  distance field)
- Minor changes in the numerical treatment of the diffusion term, to
  enhance stability