Today we are glad to present you Enhancing active wave absorption in RANS models, our new preprint, soon to be published:
In this work we review the most common methods for absorbing waves in Reynolds-Averaged Navier-Stokes (RANS) models. The limitations of active wave absorption, originating from its initial assumption of linear wave theory in shallow waters are overcome and the range of applicability is extended to any relative water depth conditions by re-deriving the formulation. The new Extended Range Active Wave Absorption (ER-AWA) overperforms the traditional implementation in all the tests performed, which comprise solitary waves and regular waves from shallow to deep waters. Moreover, the combined use of a relaxation zone and ER-AWA is tested to further reduce wave reflections. This is most often achieved for a given set of parameters, although some case by case tuning of the relaxation zone parameters would be needed to obtain the best overall performance.
As mentioned in the abstract, the significance of this paper lies in re-developing the simple active wave absorption theory presented in Schaffer (2000) to extend its range of applicability to any relative water depths.
The benefits of the new absorption are easily noticeable, as presented in the video above. As you can see, the reflections in deep waters have been greatly reduced with respect to the former implementation.
The new implementation for ER-AWA will be made available soon in olaFlow's GitHub site.