Dear all, We have now fixed one of the bugs which prevented the Floquet stability analysis part of Nektar++ from working correctly. The updates to the code are currently in the fix/floquet branch in the code repository. This will most likely be merged into the main codebase in the near future. We have tested the HalfMode variation of the code with a cylinder testcase and this accurately reproduces results from Barkley & Henderson (1996). I have attached example files for reproducing the critical case at Re=188.5/beta=1.585, which you should be able to run directly as follows. 1. Generate the time-periodic 2D base flow. IncNavierStokesSolver m32_base.xml This will also extract the field variables at a few history points which can be used to calculate the base flow frequency parameter "Freq", required for the following steps. Note that this simulation runs for 2000 time units, necessary to ensure the flow reaches a truly periodic state. 2. Generate the 2D base-flow slices for stability analysis IncNavierStokesSolver m32_slices.xml This will evolve the base flow for one period and create 32 slices (33 files, numbered 0 to 32) as checkpoint files which will be Fourier-interpolated to provide the base flow. 3. Run the 3D stability analysis. IncNavierStokesSolver m32.xml Note the specification of the base flow now uses the C-style printf format for specifying the baseflow slices. It should converge in around 20-30 iterations and the leading eigenvalue should be very close to 1.0. The "Re" (and therefore the "Freq") and "beta" parameters can be adjusted to compute the other Floquet multipliers from the paper. Note: there is still a bug with the SingleMode and MultipleModes mode types. We will update you when these are also fixed. Please let us know if you encounter any further bugs while using the HalfMode setting. Cheers, Chris -- Chris Cantwell Imperial College London South Kensington Campus London SW7 2AZ Email: c.cantwell@imperial.ac.uk www.imperial.ac.uk/people/c.cantwell