[LMD]

Hi, Reef3d Team

I’m trying to generate cnoidal waves in FNPF（h=0.5, H=0.21, L=4, according to example in SFLOW）but encountered some problems.

First, I used B 98 2 & B 99 1 but the amplitude is much smaller than theory. Then I tried B 98 3 & B 99 3 and made some options based on it, such as:

• modified dx (0.04 -> 0.02 -> 0.01 -> 0.005)
• modified cfl (0.2 -> 0.1)
• increasing cell number in z-direction（10, 20, 30）

However, the result is still not ideal enough.

I don’t know where the problem is, so I hope to get some help.
Thank you very much.

[valgrinda]

Hi Xu Hui,

- as we don't have the potential formulation for cnoidal waves, you need to use either B 98 3 or B 98 4 (velocity based using potential gradients).

- for DIVEMesh, you could increase the stretching factor B 113 (more cells towards the fsf), e.g. 3.5

- another thing: you are prescribing quite steep waves, sure that the theory still covers that? For cnoidal waves, your waves are relatively short. I.e. do you still expect a complete match between the theory and the numerical, which includes all wave-wave-interactions and non-linearities? Have you checked that you use the correct wave theory? Have a look at SSGW (B 92 70 + relaxation wavegen), that could be a better match for your desired waves.