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-   -   How do I set scalar boundary condition? (https://www.cfd-online.com/Forums/siemens/55702-how-do-i-set-scalar-boundary-condition.html)

 D.K lLee November 22, 2006 22:47

How do I set scalar boundary condition?

Hi, everyone..

I have something make me confusing.

I am trying to analyze SI engine(of course, with octane)

I am using Weller-1 model with conditional enthalpy model.

Then, I got 6 scalars (C8H18, N2, O2, CO2, H2O, RVB).

I don't know the meaning of RVB but it's not a problem.

I have set initial mass fraction of initially charged AIR of scalars like below.

(C8H18:0.0637, N2: 0.7183, O2: 0.218, RVB: 1)

I've referenced theoretical fuel equivalence ratio of octane and RVB fraction as weller model tutorial.

Now, I have a question. When I set boundary scalar mass fraction of the inlet, what value I have to use for RVB?

Same as initial field? Anyway, I temporarily setted the inlet RVB mass fraction as 1 and found that combustion was successfully have occured. But I want to get a more precise information about setting RVB mass fraction.

Thank you~

 Robert_B December 5, 2012 14:24

RVB is regress variable b. It's a non-dimensional scalar variable, which has value 1 in the unburned state and 0 in the fully burned state. It is defined in the StarCD methodology volume.

Presumably your inlet stream is a mixture of fuel, oxygen and nitrogen? Assuming that the stream is completely unburned where it enters the domain, you should set the stream's value of RVB to be 1.

Robert

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