[Kaushik15]

Hi,
I am trying to validate the results obtained through REEF3D with the experimental results for monopile scouring. I am able to compare the final S/D value obtained at equilibrium. However, I am having trouble getting the correct scouring vs. time graph.

I have observed that the morphological solver is decoupled and by default runs at a maximum timestep of 10 seconds for every 10 iterations of the hydrodynamic solver. How do I get a time-accurate representation of scouring (scouring vs. time) since direct coupling with the hydrodynamic solver is not possible?

[harenaobsidet]

Hi Kaushik,
The sediment time is decoupled from the hydrodynamic time as the sediment time scale is usually a lot larger than the hydrodynamic time scale and running the sediment algorithms would slow down the simulation significantly.
You can force both cycles to run at the same time if you want by using S 42 1 and S 44 1.
However, we usually don't print out results every step so as long as a sediment calculation is performed in between each print out it should not change anything.
And for a scour vs time graph you can use ParaView to create a graph from the output files.

[Kaushik15]

Thanks for the answer.

However, the morphological solver time step with respect to the hydrodynamic solver is actually affecting the amount of scouring that is occuring. Is that supposed to happen? Also, I thought scouring could be directly plotted from the SedimentMax.dat output file?

Is there any other less computationally expensive way to get a proper scouring vs. time plot?

[harenaobsidet]

The time step ratio should not influence the results, but I don't know if the dynamic behaviour is identical which different ratios. You could take a look into: Ahmad N. (2018) High-Resolution CFD Modelling of Scour in the Marine Environment, Doctoral Theses at NTNU Trondheim.

Yes, for a S or S/D over time plot SedimentMax is enough. The print-out there is also related to the sediment time step.

If you need higher temporal resolution, there is no way to avoid reducing the sediment time step.

[Kaushik15]

Thank you for answering.