Analytical adjoint

Change potential and mesh derivatives to analytical. Also changed the residuals computation of the viscous solver to the analytical expression instead of solving the linear system. This commit reduces the computational cost of the coupled adjoint methodology by a factor 4, at least.

Add adjoint capability

The api features 3 components: The solver, the geometry and the initial mesh. The api is tested in a aerodynamic shape case where the NACA0012 is constrained at 0deg AoA with cl=0.40 and the objective function to minimize is the drag wrt the max camber and the max camber position. The test case ends with a final shape close to the NACA4412 (camber = 35% & max camber pos = 41%)

Friction drag is now part of the implementation. The rhs of the adjoint system is updated and the test uses total drag. The adjoint test now uses the mesh update capability.

New surface mesh is imposed in the viscous solver in 2D and stagnation point is recomputed at the first coupling iteration

Added adjoint for AoA and mesh in 2D. Nodes indices are now passed to the BoundaryLayer object

Changes are relative to adjoint and api modifications.

Following commit that removes VII from dartflo

Cp is not written since VTK changed the name of their function. Writting cp slices works with VTK 9.3.0

Increased number of elements in the TE region and updated tests values.

Refactor interface

Adjoint is not working because the delta star box is missing

Boundary layer c++ objects are created in python with swig and are manipulated by the interface. The initial condition of the viscous solver was changed. All test cases have been adapted. A decrease in the number of iterations is globally observed. Results are slightly improved especially for the RAE validation case.

Merged agardTest branch

Validate 2D transonic capabilities.

Driver now computes the average position of the transition

DDicretization now throws a runtime error if the mesh size is < 2 elements.

VTK now supported + pipeline fixed for 3D cases.