intro story Coast / Estuary

Coast / Estuary

Coastal systems are among the most dynamic physical systems on earth and are subject to a large variety of forces. The morphodynamic changes occurring to coastlines worldwide are of great interest and importance. These changes occur as a result of the erosion of sediments, its subsequent transport as bed load or suspended load, and eventual deposition. 
 
Estuaries are partly enclosed water bodies that have an open connection to the coast. Estuaries generally have one or more branching channels, intertidal mudflats and/or salt marshes. Intertidal areas are of high ecological importance and trap sediments (sands, silts, clays and organic matter).
Within the Delft3D modelling package a large variation of coastal and estuarine physical and chemical processes can be simulated. These include waves, tidal propagation, wind- or wave-induced water level setup, flow induced by salinity or temperature gradients, sand and mud transport, water quality and changing bathymetry (morphology). Delft3D can also be used operationally e.g. storm, surge and algal bloom forecasting. 
 
On this discussion page you can post questions, research discussions or just share your experience about modelling coastal and/or estuarine systems with Delft3D FM. 
 

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Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

 

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DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw file

U
Anonymous Anonymous, modified 7 Years ago.

DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw file

I'm probably being an idiot but would appreciate enlightenment ...

I'm trying to impose a time-varying wave boundary condition in a WAVE only model using the .bcw file approach. However, it appears that the information entered in the .bcw file is not being used - rather the information contained in the .mdw file appears to be taking precedent. My understanding is that by including the keyword "TSeriesFile" in the .mdw file, information contained in the .bcw [e.g. Hs, Tp, theta & spread at each time step] supercedes any information in the .mdw file.

Let me try to explain by way of example. In the following instances the model executes without error, just the results are not what I expect & I can't understand why this should be the case.

The domain is a simple rectangular one with wave boundary conditions specified on the single offshore boundary [no conditions imposed on the lateral boundaries]. The .bcw file contains the following [I've included only three times steps for simplicity].

location 'NW Boundary (Seaward)'
time-function 'non-equidistant'
reference-time 20120301
time-unit 'minutes'
interpolation 'linear'
parameter 'time' unit '[min]'
parameter 'WaveHeight' unit '[m]'
parameter 'Period' unit '[ s ]'
parameter 'Direction' unit '[N^o]'
parameter 'DirSpreading' unit '[^o]'
0.000000 1.0 5.0 270.0 30.0
30.000000 3.0 9.0 315.0 20.0
60.000000 5.0 13.0 360.0 10.0

Following the guidance in section A2.8.2 of the manual [v3.05.26485], the .mdw file includes:
  • the keyword 'TSeriesFile = filename.bcw' in the General group;
  • multiple Timepoint groups listing the three Time & WaterLevel/XVeloc/YVeloc values for each time step in the .bcw file; and,
  • a single Boundary group described below.


When the Boundary group makes no reference to parameters WaveHeight, Period, Direction & DirSpreading, as in the examples on page 157 of the manual, e.g.
[Boundary]
Name = NW Boundary (Seaward)
Definition = orientation
Orientation = northwest
SpectrumSpec = parametric
SpShapeType = pierson-moskowitz
PeriodType = peak
DirSpreadType = degrees
PeakEnhanceFac = 3.3000000e+000
GaussSpread = 9.9999998e-003

the output peak direction appears to differ radically to that stated in the .bcw file (from the north-east rather than a little north of west - see ScreenShot016.jpg).

When the parameters are included and assigned notional values, i.e. adding the following to the Boundary group above,
WaveHeight = 1.0000000e+000
Period = 6.0000000e+000
Direction = 3.1500000e+002
DirSpreading = 5.0000000e+000
it is these values that are replicated in the output at each time step rather than the conditions in the .bcw file (see ScreenShot017.jpg.)

Does anyone have an idea what I am doing wrong?

Thanks
Ruairi
U
Arnold van Rooijen, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Hi Ruairi,

I am not sure why your model is not working, but did you also try the wavecon-approach (that's what I usually use)? If you add a file with the name "wavecon.RUNID" to your simulation directory, the model should use that information instead of the prescribed conditions in the mdw.

Example of the layout of a wavecon-file:

* Itdate Hs Tp Dir ms wl windspeed wind dir
BL01
52352 8 * nr of rows, nr of columns
5.256000e+05 0.76 8.60 275 4 0 0 0
5.256100e+05 0.70 8.60 277 4 0 0 0
5.256200e+05 0.69 8.60 275 4 0 0 0
...

Hope this helps.

Cheers,
Arnold
U
Anonymous Anonymous, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Hi Arnold,

Thanks for your response.

I've used the wavecon file approach previously [succesfully]. However, it is not appropriate for my present situation. My understanding is the wavecon file approach applies the conditions specified in the wavecon file for each time step to all the boundaries specified in the model. My present situation requires the conditions at a particular time step to vary spatially on the model boundaries and this requires the .bcw file approach.

Still pondering the peculiarity, so if anyone else can shed some light on it I'd be grateful.

Cheers
Ruairi
Qinghua Ye, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f (Answer)

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Ruairi,

As I wrote in the email, the name of boundary exceed the array length. Thus the boundary you specified in the BCW is not used by the model. If the name of the bc shortened a bit, the bcw type boundary gives the same result with wavecon, or other types of wave boundary conditions.

Regards,

Qinghua
U
Anonymous Anonymous, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Hi Qinghua,

Many thanks for resolving this.

It seems my initial sentence was accurate - I was being an idiot. I'd checked the boundary name was repeated accurately but hadn't considered the character string length. One to remember in the future - keep keywords simple and short.

One question, if the model didn't recognize the bcw file and the mdw file didn't provide any wave parameters, from where did the model get its wave conditions shown in the figures? Are there any default settings?

Once again many thanks
Ruairi
Qinghua Ye, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Dear Ruairi,

Yes, there is a certain priority for the model to choose wave BCs. If wavecon presents, the model will take the wavecon as the first priority. BCW should be specified if you want to use it. In your case, I guess the wave model take the default values, which might be 0, or -999.000 as input and leads to garbage out.

Regards,

Qinghua
MR
mohammad rahmanian, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Youngling Posts: 6 Join Date: 5/27/12 Recent Posts
Hello Dear.Qinghua Ye

I would be appreciated if you could tel me How I can define wavecon.rid file for multi wave boundary condition?

I have defined time varying wave parameters (wavecon.rid) stationary mode for ONE OPEN BOUNDARY (BL01), But I dont know how can define it , in case that we have more than one time varying wave boundary condition? (for example we have two boundary west and east and also we have time series wave condition for each one)

Regards

Mohamad
Qinghua Ye, modified 7 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Mohamad,

We cannot use wavecon.rid for multiple boundaries. You have to choose other options, refer to Delft3D-WAVE manual, A.2.8.2, A.2.8.3 and A.2.8.4.

Happy 2014!

Qinghua
AM
Abdulla Mohamed, modified 6 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Youngling Posts: 16 Join Date: 6/12/13 Recent Posts
Hi Everyone,

Some good information in this thread and this had really helped me getting started with the my wave model boundary conditions.

I am having a few problems tying to understand the boundary conditions definition for the wave model.

1. I was wondering if the best way to apply a time varying but spatially constant wind boundary condition would be to use a wavecon file? Is this also true to apply a time varying wave height/period/direction on one of the boundaries of the model, i.e. Using a wavecon file? Is the wavecon the only way of applying a time varying waveheight/period/direction boundary together with a time varying wind boundary condition?

The second question I have is in regards to running a nested wave model.
I would like to run the wave model with a fine grid nested inside the coarse grid
In regards to this I was wondering:
2. I have com file outputs from the hydrodynamics run for both the coarse and fine grids. When nesting these two grids in the wave model, do I have to use both com files from the coarse and fine grids hydo runs. It seems like there is the option to use only one hydro com file in the wave model run.

Any input regarding this will be much appreciated.

Thanks a lot,
Abdulla
RC
Rodrigo Carballo, modified 6 Years ago.

RE: DELFT3D-WAVE: Imposing time-varying wave boundary conditions via .bcw f

Youngling Posts: 19 Join Date: 5/27/11 Recent Posts
Hi Qinghua:

I am experiencing the same problem as Ruairi. I have tried to shorten the names of the boundaries but still doesn't work. I have created the files following the instrucions of the manual but the model ignores the .bcw file and the wave model takes the default value -999.000 as input and leads to wrong results. If I try to run the model in the standalone mode with the same conditions the model works properly, therefore, for some reason the model is not reading the the .bcw file and I don't know why.

P.S.- I attach the model.