Hi all,

For a bacteria that travels through my domain in which a UV lamp is present, I want to calculate the ammount of UV radiation it collects (CFX 5.6). I can do this with an additional variable that integrates the collected radiation, but this variable mixes up in the turbulent field leading to averaged values. I am not interested in the worst averaged value, I absolutely need the worst value.

Thus, what I am looking for is a modified variable, that is not subject to mixing. Anyone?

I have been trying to plot streamlines in Post and exporting the integrated radiation over these streamlines but that does not work for individual streamlines. Particle tracking?

Kinds regards, Pascale.

Pascal,

Typically these "bacteria" are very dilute and don't really diffuse as a chemical species would. They behave more like particles caught in the streamlines of the flow field. For this reason, I've used non-diffusive additional variables (set under variable type). Also, you'll want to minimize any numerical diffusion (use high order differencing in both space and time and as fine a grid as you can stand).

Jeff

Hi Jeff,

If have been using this and results are acceptable but I would like to improve things. Thus I curious whether someone knows how to use particle tracking to integrate the radiation. Integration over streamlines would also be fine. However, in Post nor Fieldview it is possible to integrate over individual streamlines.

Cheers, Pascale

Pascale,

You can do a length integral on a streamline or particle track in Post.

-Robin

Check out the work done at the University of Nottingham with CFX-5 on this topic. It was published, among other things, in CFX-Update.

Hi Pascale,

If you want to solve a pure tranport equation, don't define the kinematic diffusivity at all (leave it unchecked). The solver will then leave out both the kinematic and turbulent diffusion terms.

Regards, Robin

Robin,

I can do that but not on individual tracks. I will try other optioned mentioned in this thread.

Pascale.

You could always seed individual tracks from single point objects.

-Robin