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Hello,

I've got a question concerning the tracer configuration.

I have a mesh on which I define 2 boundaries, the one downstream with prescribed elevation and the upstream boundary with prescribed flowrate (done with time curves in Fudaa).

To set the tracer, I first do right-click in the 2-view, add a tracer and give it a name (16 units for the name itself and then the units). As initial value, I set 0.
In keywords, I give the tracer a prescribed value (PRESCRIBED TRACER VALUES) for the boundaries. Back in the 2d view, I select the defined tracer at the inflow boundary, and chose it as variable in time (as I define it with a function (time curve).
At the outflow boundary, I set the tracer as constant with the value 0 (= PRESCRIBED TRACER VALUES on boundary 2).

However, when I analyse the results after computation, the tracer value is equal to 0 (min 0, max 0).

I attach the other modified keywords and the cas file.

Thanks!

Hello

I can not check the problem only with these two files. With the whole model, it could be easier.
Meanwhile, verify that in the boundary condition file you have set 5 in the column dedicated to the tracer input and 4 at the outlet (which is much more convenient for you case).

I hope that this helps
with ly kind regards

Riadh ATA

Thanks for your answer riadh,

the tracer works. But: I notice that the tracer decomposes itself... so is it by default a decaying tracer? How can I change that (in the means of keywords?), so that it becomes a non-decaying tracer? Do I have to modify the diffusion or advection terms?

Hello

This is not a matter of advection neither diffusion, the decaying is linked to source terms.
To change the law you can play with the keyword LAW OF TRACERS DEGRADATION which is 0 by default for conservative tracers. If you set 1 for this keyword, the exponential decaying law is activated.
If you need other laws, you can edit subroutine prosou.f

with my kind regards

Riadh