DELWAQ

DELWAQ is the engine of the D-Water Quality and D-Ecology programmes of the Delft3D suite. It is based on a rich library from which relevant substances and processes can be selected to quickly put water and sediment quality models together.

The processes library covers many aspects of water quality and ecology, from basic tracers, dissolved oxygen, nutrients, organic matter, inorganic suspended matter, heavy metals, bacteria and organic micro-pollutants, to complex algae and macrophyte dynamics. High performance solvers enable the simulation of long periods, often required to capture the full cycles of the processes being modelled.

The finite volume approach underlying DELWAQ allows it to be coupled to both the structured grid hydrodynamics of the current Delft3D-FLOW engine and the upcoming D-Flow Flexible Mesh engine (1D-2D-3D) of the Delft3D Flexible Mesh Suite (or even other models such as TELEMAC).

'DELWAQ in open source' is our invitation to all leading experts to collaborate in further development and research in the field of water quality, ecology and morphology using Delft3D. Feel free to post your DELWAQ related questions or comments in this dedicated forum space. If you are new to DELWAQ, the tutorial (in the user manual) is a good place to start. A list of DELWAQ related publications is available here.

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D-Flow Flexible Mesh
DELWAQ

Cohesive sediments & muddy systems

 


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Problem with coupling a ddb file

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Problem with coupling a ddb file
ddcouple delwaq
Answer (Unmark)
3/15/17 3:08 PM
Hi

I have a problem with coupling a ddb file. when I open ddb file stop time and time step are different from the related files. stop time is shorter and step time is 4 hrs however in 3 related hyd file they are 2s. Anyway I coupled that ddb file but when I opened that file in the Define input-Hydrodynamics it says there is a problem with discharge. what should I do? do you have any idea what is the problem?

Best Regards,
Fateme
RE: Problem with coupling a ddb file
Answer (Unmark)
3/23/17 5:00 PMas a reply to fateme Mahyari.
Hi Fateme,

Your description is quite general. Is this a 'classic' dd calculation with separate grids? Then it might be that the WAQ output period and intervals might be set differently across the domains. These settings must be the same for all domains. With 'parrallel' dd running (only one grid) it should be the same for all grids automatically

greetings,
Michel
RE: Problem with coupling a ddb file
coupling ddcouple delwaq ddcouple
Answer (Unmark)
3/28/17 4:58 PMas a reply to Michelle Jeuken.
Hi Dear Michel
Thanks for your respond. My model has 3 grid parts. All of three parts have the same time step, start and stop. but in ddb file stop and step time changes. as you can see in the attached file. Ignoring all of those issues I tried to couple hyd file which I saved with that ddb file but it ended with error which I attached it as well. The output in flow module works very good, but I do not know what is the problem. do you have any Idea what should be wrong?
Thanks
Regards,
Fateme
Attachment

Attachment

Attachments: Problem.png (32.1k), after starting.png (25.5k)
RE: Problem with coupling a ddb file
Answer (Unmark)
3/31/17 10:58 AMas a reply to fateme Mahyari.
Hi Fateme,

Hm, that looks a bit strange. The ddb file does not contain any information on the time step, so it shouldn't come from there. Could you post your ddb-file and hyd-file?

I also must say that the communication time step of 2 seconds is quite small for water quality.

regards,
Michel
RE: Problem with coupling a ddb file
coupling ddb ddcouple delwaq
Answer (Unmark)
3/31/17 5:03 PMas a reply to Michelle Jeuken.
Hi Michel

Thanks for your reply. I attached my ddb and hyd file. what is your suggestion about time step?
Attachments: G7_DD_run2_RSTRT.ddb (0.2k), G7_DD_run2_RSTRT.hyd (2.8k)
RE: Problem with coupling a ddb file
Answer (Unmark)
4/3/17 10:35 AMas a reply to fateme Mahyari.
Another issue I could think of is that you might be using WAVE? This will affect the com-*.dat files in such a way that coupling with WAQ is not possible any more. To solve this, you should switch on Export WAQ Input to produce direct input for Delwaq (see screenshot below). You should then run ddcouple using the ddb-file as it is produced by FLOW. You don't need to create a hyd file with the coupling user interface.

And the best time step for communication with WAQ depends on the study area. On the one hand, the time step you choose is the biggest time step that you can use in the WAQ model. In tidal and dynamic systems it would be wise to be in the range of 5-30 minutes. Otherwise I usually see time steps of 1-3 hours.
Attachment

Attachments: Switch on WAQ output Delft3D 4.png (57.5k)
RE: Problem with coupling a ddb file
Answer (Unmark)
4/3/17 8:00 PMas a reply to Michelle Jeuken.
Hi,

I can jump in since I'm working with Fateme on this project, and I'm the one that made the hydrodynamic model at issue here.

A couple points of clarification:
1) We're not using WAVE, and are currently exporting the WAQ inputs from the control dialog box
2) The very short time step is required for the FLOW grid, since we're working on a very small area at high resolution (~400m long by 150m wide pond, with cells getting down to 1m2). I've tried running WAQ at a different time step, but hit an error saying it's not being scaled by an integer value (even if it is). Because of this, the WAQ time step is kept the same as FLOW.
3) This is a classic DD implementation, with three separate. non-nested grids. We implemented it this way in order to better handle some complicated geometry that occurs because of a baffle in the pond.
4) The time steps (and all other FLOW parameters) should be the same for all grids.

Really appreciate your help here- it's a cool project, but the shape of the system really need the DD in place, and it's creating a ton of hiccups trying to couple it.

Thanks,
Alexander
RE: Problem with coupling a ddb file
Answer (Unmark)
4/13/17 11:26 AMas a reply to Alexander Rey.
Hi,

Well, you should be able to set the output for WAQ at a higher interval than the FLOW calculation time step to reduce the size of the communication files for WAQ. Then you should be able to use a bigger time step in WAQ. What program complains about the time step, FLOW of WAQ itself?

It is a bit difficult to guess what goes wrong here. I think it helps if you post the three mdf files, and the three hyd files of the last run you tried.

You seem to be using an older (> 2 years old) version of the FLOW kernel, since the hyd file posted above doesn't contain a header.