[NTNHAN]

Dear Professor Hans Bihs, Arun Kamath, Team REEF3D and all members,

I have a problem when I try to simulate the scour around piles following the paper: "Three-dimensional numerical modelling of wave-induced scour around piles in a side-by-side arrangement"
Link: https://www.sciencedirect.com/scienc...78383917305604

The problem comes from section 3.4 Partial decoupling (page number 142 of the paper), I attached the figure below for convenience.

Hope to receive your help.

Thank you.

[valgrinda]

Hi,

what is the problem excactly?

[NTNHAN]

Hello Professor

This is my problem:
1. I do not know how to define the values for the number of waves (N) and decoupling factor (DF) in your paper.

2. I want to define some parameters in REEF3D.
2.1 Number of waves (N) (I think: S 44 30, with N=30)
2.2 The morphological run for a duration of t=3600s (I think: S 19 3600)
2.3 The flow simulation time between the transport calculation is Δt/T=1/150 (I think: S 46 1/150 OR S 46 T/150 OR S 48 1/150).
2.4 Do we need to declare DF, Δt, Δts in REEF3D?

3. I attach control.txt and ctrl.txt files following parameters from your paper. Please help me check (if possible).

Please give me your recommendation.

Respect thank Professor.

[Ronja]

Hi,


- The number of waves is basically defined via the stopping criteria time (how long you will run the simulation for), e.g. S19 for the morphological time or N 41 for the hydrodynamic time
-> let's say you choose S 19 3600 sec as your stopping criteria, then the morphological time is your scale


- flow simulation time between the transport calculation 'dt_hyd_sedcalc': S 42 3 (-> t/T) AND S 48 1/150 [for further context: you can also use other scales for this time span which would be S 42 1 (-> nr of iterations, e.g. S 44 10) OR S 42 2 (-> hydrodynamic time, e.g. S 46 0.02 sec)]



- DF is defined as the ratio between the morphological time step and the hydrodynamic time in between the sediment calculations. Hence, if DF = 2, the morphological time advances twice as fast as the hydrodynamic time.


- you can define the morphological time step 'dt_sed' with S 15 2 (fixed instead of adaptive) AND S 13 'your desired dt_sed according to your chosen DF'


Example:
T = 4.5sec -> flow simulation time between the sed transport calc dt_hyd_sedcalc= 4.5/150 = 0.03sec, usually 3600 sec are equal to 3600/4.5sec = 800 waves.

If you choose your morphological time step with a DF = 2: dt_sed = 2 x dt_hyd_sedcalc:
-> t_sed_total = 3600, defined by S 19
-> but t_hydr_total = 3600/2 = 1800 -> 400 waves
The higher the factor DF, the less waves are imposed since the total morphological time is the stopping criterion and it advances faster than the hydrodynamic time with a higher DF. As a logical step: also, the higher the decoupling, the faster your computational time will become.



An extended explanation, hope that helps.

[NTNHAN]

Hello Ronja.

Thank you for your response.

Your answer is very clear.

One more issue is about Wave Generation and Beach parameter (B96).
For reduced-length NWT using the AWA method related to the above paper.
I guess B 96 0 0 (is it right?).
The Flow simulation time before sediment transport starts is t=25s, I guess S 45 25 (is it right?)

Best regards.