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Using DELWAQ with a single-column hydrodynamics time series (U/V/density)

SB
Sebastien Blaise, modified 11 Months ago.

Using DELWAQ with a single-column hydrodynamics time series (U/V/density)

Youngling Posts: 2 Join Date: 1/27/17 Recent Posts

Hi,

 

I have been provided a time series of horizontal velocity and density at a single location along the water column, to be used in a pollutant dispersion study. It is a relatively flat area with little spatial variability of the hydrodynamics. 

 

Can such data be used in a Delwaq simulation? Should I generate a .hyd file from it?

 

Thanks

AM
Arjen Markus, modified 11 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Jedi Knight Posts: 223 Join Date: 1/26/11 Recent Posts

When I first read your message, I thought it was the wrong kind of question, but reading it more carefully, I realise what it is all about. Yes, as a matter of fact, you can use such data to construct a hydrodynamic database of sorts. Depending on what kind of resolution in the horizontal you want it could actually be easy. If you want one column, then the thing to do is: set up a one-column model with Delft3D-FLOW or D-FLOW-FM - use the number of layers you want and the layer thicknesses you want (the latter is not strictly necessary though). Then run it for a short period. This gives you the hyd-file and the grid files you need, as well as several others. You will then need to replace the volumes and the flows files: the volumes file contains the volumes per segment, per time. The flows file contains the flow rate through every exchange area  - flow velocity time surface area for both the horizontal and vertical exchanges.

The actual contents of these file is described in the manuals, but for a simple flow field as you indicate it is not hard to construct a proper set of such files.

SB
Sebastien Blaise, modified 11 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Youngling Posts: 2 Join Date: 1/27/17 Recent Posts

Thanks. It seems like a very pragmatic and efficient solution.

 

A follow-up question (I am a new user, still waiting for the GUI): can we model in DELWAQ a buoyant tracer that will sink/rise according to its density and concentration, despite the fact there is no feedback from the tracer distribution to the hydrodynamics? In other works: can DELWAQ include buoyancy effects due to a different effluent density compared to the ambient waters? 

AM
Arjen Markus, modified 11 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Jedi Knight Posts: 223 Join Date: 1/26/11 Recent Posts

Well, inorganic matter (IM1, IM2, IM3) are the substances we use to model suspended solids, but there is no reason why the settling velocity should be positive only. In fact I have used a _negative_ settling velocity to model microplastics lighter than water. Consult the manual to see if the current implementation wrt the settling velocity as function of salinity and the concentration suits your requirements. Otherwise it is possible to define your own processes vai "Open PLCT".