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Wang Xin May 8, 2003 01:24

Beginner---Value of mass flow rate

I met a problem in Large Space stimulation,I simulate the indoor airflow in Large Space .Can you give me an explanation of how the nett sources of R1 are calculated in the result file ,and tell me what's the physical meaning of R1. I have stimulated the input library case i202.I'm unsure how to get the value of mass flow rate of the outlet and inlet.And I want to kown whether R1 is related with mass flow rate or not .Can you give me a formula of calculating the value of mass flow rate . Thanks a lot .

John Ludwig, CHAM May 9, 2003 12:20

Re: Beginner---Value of mass flow rate
The R1 source reported in the RESULT file is the mass flow rate, with units of kg/s. Positive means into the domain, negative means out of the domain.

At fixed pressure boundaries (outlet objects), the siurce is calculated from:

m = sum_over_all cells(area_of_cell*COefficient*(Pext - Pcell))

where COefficient and Pext are set in the outlet object attributes dialog. The recent thread on FREE BOUNDARY covers this topic in more detail

Wang Xin May 10, 2003 02:30

Re: Beginner---Value of mass flow rate
Hi ,

Thank you for your help.

And I expect you can tell me how to get velocity of the openings by using R1.

I'm unsure that the velocity can be calculated from
: X velocity=U1/R1;Y velocity=V1/R1; Z velocity=W1/R1

If the formulas above are right,i conclude that : the Value of mass flow rate=X(Y or Z) velocity * area of opening * density.

Am i right?

I 'm looking forward to your reply.

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