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intro story 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.




Sub groups
D-Flow Flexible Mesh

Cohesive sediments & muddy systems


Message Boards

Grid orientation problem (D3D-FLOW)

Yahia Kala, modified 1 Year ago.

Grid orientation problem (D3D-FLOW)

Youngling Posts: 12 Join Date: 7/11/13 Recent Posts

Hi All, I have a grid that I have converted from a structured finite element model. The grid covers a river and a floodplain. The gridlines meander quite a bit but are pretty smooth but have some areas with bad orthogonality. The node numbering is proving to be quite problematic when I try to run the model.


I get the following error:


*** ERROR Grid orientation incorrect: Delft3D requires (M,N) to form a counter-clockwise coordinate system.


I noticed that this check was a recently added feature in this release notes page:



I can't really get around this issue by rotating the grid administration. My geometry and gridlines are such that the numbering can never be counter-clockwise in every part of the domain.


Why is this constraint in the model and what can I do about it?


Yahia Kala, modified 1 Year ago.

RE: Grid orientation problem (D3D-FLOW)

Youngling Posts: 12 Join Date: 7/11/13 Recent Posts

I solved my own issue: I simply reversed the row coordinate arrays I was using to generate the grid. Now the numbering is 'counter-clockwise', as in, when you move along increasing m-values, the n-values are increasing to the left.