New Functionality
- The definition of material properties has been reworked and extended, both for frequency and time domains.
- Thin interior walls—hard, with acceleration, impedance or perforations—can now be defined directly as boundary conditions. No modification to the geometry is necessary.
- The Scattered field formulation no longer makes any assumptions about the incident field. This makes it easier to model complicated situations with both fluid-fluid and fluid-solid interfaces.
Backward Compatibility
All backward compatibility issues are planned to be solved for version 4.0a unless explicitly stated.
Transient Aeroacoustics
Transient Aeroacoustics with Flow is not available in version 4.0.
Ultraweak Formulation
The ultraweak formulation is not implemented in version 4.0 and is not planned for re-implementation in its previous form. The reason is that this formulation is very difficult to use without basis element order adaptivity (p-adaptivity).
Pair Boundary Conditions
Only the Continuity pair boundary condition is available in version 4.0.
All previous pair boundary conditions can be implemented manually using the src2dst_<pair name> and dst2src_<pair name> operators.
Weak Constrains
Weak constraints are not available in the acoustics physics interfaces in version 4.0. These can be entered manually using the equation view.
Cylindrical PMLS
Cylindrical PMLs in 3D are not available in version 4.0.
Far-Field Postprocessing
Far fields are not automatically read from 3.5a models into 4.0. You can add a Far Field Calculation node and manually specify this functionality.
Compressible Potential Flow
The Compressible Potential Flow physics interface in version 4.0 is not yet backward compatible with the corresponding application mode in version 3.5a.
Boundary Mode Aeroacoustics
The Boundary Mode Aeroacoustics physics interface in version 4.0 is not yet backward compatible with the corresponding application mode in version 3.5a.

