Hi Miguel, there are currently only two types of boundary conditions implemented in the APESolver. Rigid wall and "None". In theory, the latter should be non- reflecting because we only consider the outgoing invariants. However, this can lead to numerical oscillations that, depending on your setup, can be more or less significant. Both BCs are used in the "APE_2DPulseWall_WeakDG_MODIFIED.xml" example. A proper non-reflecting BC is currently not available. Cheers, Kilian Am Freitag, 16. Oktober 2015, 17:08:50 schrieb Sherwin, Spencer J:
Dear Miguel,
Kilian Lackhove (cc’ed above) has been working on this solver most closely so may be in a better position to response. However if you have set up a Riemann type solution at the boundary they should be a reasonable first attempt at non-reflecting boundaries. Can I ask what boundary conditions you are currently setting up?
Cheers, Spencer.
On 16 Oct 2015, at 13:30, Miguel Moratilla-Vega <M.A.Moratilla-vega@lboro.ac.uk<mailto:M.A.Moratilla-vega@lboro.ac.uk>> wrote:
Dear Spencer,
I am trying to solve the simple acoustic wave problem, imposing a Gausian pulse as an initial condition. I am using the APE solver to obtain the acoustic propagation, but at the boundaries of the domain I am having reflections. For that reason I was wondering if there is any method in Nektar implemented to avoid these reflection in the outer boundaries of the domain.
I have tried using the Absorption forcing but it is not giving me any changes in the solution. I have noticed as well that for the Compressible Flow Solver there is a PressureOutletNonReflective boundary condition, so I don’t know if implementing this in the APE solver would solve the problem.
In addition, I have found in a paper of Tam and Webb, that they developed a Radiation Boundary Condition that it has been applied by Groschel, Schroder et al. to minimize the reflection and applied to an APE problem.
Thank you very much and kind regards,
Miguel
--------------------------- Miguel Moratilla-Vega PhD Student Aeronautical and Automotive Engineering Department Stewart Miller Building Loughborough University Leicestershire LE11 3TU
Spencer Sherwin McLaren Racing/Royal Academy of Engineering Research Chair, Professor of Computational Fluid Mechanics, Department of Aeronautics, Imperial College London South Kensington Campus London SW7 2AZ
s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052 -- Kilian Lackhove, M.Sc. Fachgebiet für Energie- und Kraftwerkstechnik L1|08 114 Technische Universität Darmstadt Jovanka-Bontschits-Straße 2 D-64287 Darmstadt Germany
Tel.: +49 6151 16 - 5186 Fax: +49 6151 16 - 6555 e-mail: lackhove@ekt.tu-darmstadt.de