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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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Sub groups
D-Flow Flexible Mesh
DELWAQ

Cohesive sediments & muddy systems

 


Message Boards

Reimann Boundary Conditios

LD
Leonardo de Jesus, modified 7 Years ago.

Reimann Boundary Conditios

Youngling Posts: 5 Join Date: 1/23/12 Recent Posts
Hi,

i'm trying to implement the Reimann BC into a 3D z-coordinate model and i've read that the formulae to calculate it is Re = velocity +/- eta*sqrt(g/h), but taking a look into the matlab routine nesthd2.m of the open earth tools I found a acor factor (defined as -dps/depth) that multiplies Re. So I want to know what is this acor factor and if a need to include it when my BC is only Reimann ('cause in the Riemann + tangential BC I don't have to multiplicate Re by the acor factor).

Thanks,
Leonardo.
Qinghua Ye, modified 7 Years ago.

RE: Reimann Boundary Conditios

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

You are right, the acor is a calibration factor, which is not shown in the formula. You can choose to use it or not. But we use it to smooth out neighouring points.

Would you update us as well after you finished your Riemann + tangential BC case?

Thanks,

Qinghua
LD
Leonardo de Jesus, modified 7 Years ago.

RE: Reimann Boundary Conditios

Youngling Posts: 5 Join Date: 1/23/12 Recent Posts
Hi Qinghua,

yes, I'm performing some simulations testing the Reimann and tangential boundary conditions. But I'm still in doubt of this smoothing (acor) and how use it. What's the criteria to smooth the Riemann BC and how to calculate it? And more, why I don't have to smooth the Riemann BC when I use the tangential BC?

By now, I implemented a 3D z-coordinate model based on Hycom-ncoda's solution for the boundary (for while, just for elevation and velocities) for a meso-scale grid (15°x20°). I'm using the same horizontal and vertical grid of the Hycom-ncoda model to avoid interpolation. The results looks fine for the velocities (for Ri and Ri+Tg BC) and the qualitative pattern for elevation looks good too, but the delft model overestimate the elevation and so comes another question that may be the cause of this error: how I define the signal into the calculation of the Riemann BC, I mean this depends on the signal of the normal velocity that cross the BC or it is defined as we find into the nesthd2.m routine (north and east BC the signal is + and it is + for the south and west BC).

I don't take a closer look into the results, comparing the Riemann BC and Ri+tg BC, but when I got it I'll reply here my findings.

Best regards and thanks for the answer,
Leonardo.
FM
florian MONETTI, modified 7 Years ago.

RE: Reimann Boundary Conditios

Youngling Posts: 21 Join Date: 3/12/13 Recent Posts
Hi Leonardo,

I also work on that but with ROMS output for generate boundary conditions.
I created my own matlab toolbox but I have the same question for the north east SOuth West signal).

I dont know if the positive magnitude was for inward current and negative for outward current or juste positve for eastward- northward and negative for westward and southward.
If someone has the answer...

Regards

Florian
Fernando Barreto, modified 7 Years ago.

RE: Reimann Boundary Conditios

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
Florian or Leonardo, did you have any advance? I'm facing the same doubt.

Thanks.