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

Delft-WAQ in parallel version

Ashok Khadka, modified 7 Years ago.

Delft-WAQ in parallel version

Youngling Posts: 3 Join Date: 6/19/13 Recent Posts
Can we compile and run the Delft-WAQ in parallel version ??
Michel Jeuken, modified 7 Years ago.

RE: Delft-WAQ in parallel version

Jedi Knight Posts: 154 Join Date: 1/21/13 Recent Posts
Yes, you can compile and run the Delft-WAQ in parallel version:

The multiprocessing is quite a new development which is generally
switched 'off', and can't be turned on using the GUI. You will
have to make an edit to the inp file used by the delwaq engine.
Please be aware that the GUI doesn't read the inp file, and
overwrites changes if you save from the GUI again.

A description of the inp-file can be found in
(http://oss.deltares.nl/web/delft3d/manuals). There you will find
that you have to add an extra line to block 7 of the input
(before #7, but after #6), to specify the maximum number of
processors to be used. From the manual:

/Parallel computing

D-Water Quality supports parallel computing on multi core PCs.
This feature is generally switched ’off’. If you are confident
with your model, you may switch it ’on’ by giving:

CONSTANTS nothreads DATA 0.0 ; OMP-parallelism ’on’

With a value of 0.0 D-Water Quality will itself determine how
many threads can be used. With a positive value you determine the
number of threads. The default is -1.0 which means ’off’.
Implicit solvers need a Krilov space for each thread. This can
become large
for e.g. 6 core PCs with hyper-threading featuring 12 threads.
Then you better use a smaller positive number for the number of
threads than the allowed number of 12 that you will get with a
value of zero.

So use it, but with care,

Ashok Khadka, modified 7 Years ago.

RE: Delft-WAQ in parallel version

Youngling Posts: 3 Join Date: 6/19/13 Recent Posts
Thank you Michel !!