## Fluids

#### Specifying boundary condition for a fluid zone

• Ramesh Chandra Mishra
Subscriber

Hi

I am trying to simulate dispersion of pollutants from fluid zones which are created in ANSYS using cell registers. I want to specify mass flow rate of pollutants from these zones. But after creating zones, they are automatically assisned as internal where I cannot assign the mass flow rate. I am attaching my geometry and a glimpse of my setup for reference. Four green lines in between the two blocks are the fluid zones which I am considering as pollutant source.

Any help is highly appreciated.

• Rob
Ansys Employee

Have a look at SOURCE terms in the fluid cell zones.

• Ramesh Chandra Mishra
Subscriber

Hi Rob

Thankyou for your time.

I have specified the same in source terms. But there are two doubts I have:

a) I have a flow rate of 10g/s for a mixture of sulphur hexafluoride and air. Even if i specify in source term, unit is kg/cubic m.s. So should I divide the flow rate by volime of the zone to obtain the value in kg/cubic m.s.

b) For a mixture of SF6 and air, I get to enter the value only for SF6. Is it okay to not specify the value of flow rate of air?

• Rob
Ansys Employee

Sources are in ?? /m3/s so it's normal to divide the source by the cell zone volume to get the correct amount.

Species modelling needs a little care, and reading of the manuals & tutorials (Help in Fluent will get you to both). In Fluent we solve for n-1 species, so in your case we'll solve where the SF6 goes and assume anything else is air in the species equations. So, you need to add a mass (total of air+CF6) to the cell zone, and a mass of SF6 (species section).

• namrata mishra
Subscriber

Hi

I am using species transport model to see dispersion of species from a source. I need to obtain mass concentration of species on a specific surface in the geometry in excel format. Can someone please help me with this?

• Rob
Ansys Employee

Probably, but posting into a new thread would help.

• namrata mishra
Subscriber

Sure

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