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incoming flow : zero concentration gradient of incoming flow.

hani ramadhan, modified 1 Year ago.

incoming flow : zero concentration gradient of incoming flow.

Youngling Posts: 6 Join Date: 3/31/13 Recent Posts

Dear all,

Is that possible to define zero gradient of concentration at open boundary so that the concentration of active substances will have the same number with ambient concentration? I need this because I don't have data about incoming flow concentration for some active substances. I really need advice about this.

Thanks and best regards

Hani Ramadhan

AM
Arjen Markus, modified 1 Year ago.

RE: incoming flow : zero concentration gradient of incoming flow.

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

Unfortunately, no, that is not possible (a limitation of the implementation, not of the mathematics, although I can see some peculiarities in that respect ...). There are two ways I can see you can solve this:

* Do a calculation with the boundary concentrations set to zero and see what "overall" concentrations develop for these substances (that will work only if you have processes that form them or waste loads that introduced them, of course. Otherwise the concentrations will remain zero).

* Use the characteristics of these substances and measurements from similar water bodies to estimate the concentrations on the boundaries.

 

Note: even if a zero-gradient boundary condition would have been possible, it would only have worked if the conditions for the first solution are fulfilled.