[ajayjatoliya]

Hello REEF3D Team

I am working on sediment transport problem for monopile, In many papers i have seen the word decoupling factor (DF).

Could you please tell me how is provide DF in ctrl file ? Is it through S 13 or S 14 ?

[harenaobsidet]

Hello Ajay,
yes, kind of. Due to the usually very different time scales for sediment and hydrodynamic they are often separated.
That is also done in REEF3D. However REEF3D does not have a fixed factor. The sediment time step is controlled using S 13, 14 & 15. Choosing S 15 0 follows S 13 + S 14 and the Courant number for the sediment while the hydrodynamic time step is also controlled by the Courant number. These Courant numbers are however not necessarily the same.
If you are not Courant limited with the max time steps you chose for both hydrodynamics (Courant dependent N 47) and sediment, you can achieve a theoretically constant decoupling factor.