Length of Wave Simulation When using Jonswap Piston
Hello,
I'm wondering if anyone has any advice on my issue.
I'm using a piston wavemaker with irregular waves in a nuumerical flume. From some literature reviews I've found that the length of a numerical simulation with a jonswap spectrum should be your peak period, Tp*150, and that the dt or "time out" should be your Tp/800, in order to properly capture a full jonswap spectrum. I'm running cases with a Tp between 3 and 7 seconds. This is creating some very long simulations even with a dpi of say .02m. Its also taking up a ton of space on my hard-drive to run these. Does anyone have any different guidance on this that could lessen my computational time? I haven't been able to find an SPH-specific paper that talks about simulation length for irregular waves.
Thanks,
Liam
Comments
Hello!
From a practical perspective you could look into how long it takes for your simulation to produce a stable signal. If your simulation produces stability after 0.5T, why let it finish to T, even if litterature requests it?
Also what litterate recommends it? Perhaps they use/work with different methods, where it is more feasible.
It could also be that what they require is correct but that the hardware you are using insufficient.
Personally I think that practically it is always a trade-off between simulation length, convergence and stability.
Kind regards
Hi,
The theoretical surface elevation is created in the WavePaddle_mkxxxx.csv file when you begin running a DualSPhysics simulation.
Hi,
I would recommend to create a domain that is long at least as 1 wavelength (in deep water, this corresponds to 1.56Tp^2).
About the output time, there is no rule, since your calculation timestep has nothing to do with that. I would use 20Hz, should be already enough to measure water surface elevation and reconstruct your spectrum.
Regards