[tchavdarov]

It looks like the CFX Monte Carlo Radiation can do the job but I am not sure - a very little is written about all the capability of this method in CFX (unlike the very detailed description of each method used b Fluent ). If you have not used it but are familiar with the details of the implementation for the method such as yes/no on: multi-band radiation, fluid absorption, wall reflection, transparent media refraction. scattering, Lagrangian particle irradiance parameter available, etc., please let me know.

[Martin_Sz]

So monte carlo method ussually is used to glass emissivity
for fluid usually I use discrete transfer
Best regards

[evcelica]

Discrete Transfer doesn't involve absorption by the fluid, it's only surface to surface. UV Water treatment would involve the fluid of course, so the Monte Carlo sounds like a way to properly model it.

[Opaque]

As a clarification, all the thermal radiation models in ANSYS CFX are for participating media including P1, Discrete Transfer and Monte Carlo. However, there is a possibility to also run Discrete Transfer and Monte Carlo for transparent media (also known as Surface to Surface).

Of all the provided models, only Monte Carlo can accurately predict radiative transfer through materials of different refractive indexes, or highly collimated radiation such solar irradiation and lens applications such as headlamps, or thermal focusing.

For highly collimated radiation, Monte Carlo is more efficient than a Finite Volume Radiation/Discrete Ordinates for the same accuracy.

For your application, what kind of radiation distribution do you have at the source: isotropic or collimated ? You should probably contact ANSYS CFX support about your application since someone else may have already done similar calculations. For non-gray modeling, have you looked at the templates under the install_directory/etc/model-templates ?

[tchavdarov]

Hi Oaque, Thank for the answers and the comments . The radiation is isotropic coming from cylindrical lamps. I did not know that CFX has DO Radiation model ( I have not used for many years). I was the first to use Fluent DO Radiation for UV water treatment more than 10 years ago but I hear for the first time that CFX has the same model. I will check on it. Why do you believe that DO radiation can not handle well radiation through a transparent material and fluid (medias with different refractive indexes)?

[Opaque]

ANSYS CFX does NOT have DO, but Discrete Transfer (or DTRM in Fluent speak). My apologies if my previous comment somehow implied that.

The only products with DO (as in Discrete Ordinates using Finite Volume Radiation method) in the market are Fluent and the old CFX-TASCflow.

If your model include materials with different refractive indexes, you have no other choice but MonteCarlo in the ANSYS CFX product.

[tchavdarov]

Thank you again. I was thinking the same way however, my search did not find a single ANSYS-CFX User that is using Monte Carlo Radiation method for UV Water Treatment (ANSYS Support did not provide any benchmark study on the same, too). The ANSYS-CFX Users (that include myself some years ago) use the flow solver + third party radiation software, primarily UVCalc of Jim's Bolton Photo Science. Most probably Monte Carlo Radiation method is too computational expensive for isotropic radiation that radiate light in all direction in the entire flow domain. For that reason perhaps no one is use it for UV Water Treatment.

[Opaque]

If your concern is the usage of multiband non-gray model, have you looked at


http://www.cfd-online.com/Forums/cfx...ost496981.html

That should be sufficient to get you started with a multiband calculation with DTM, or MC.