[Boh]

Hi!
I need to write an UDf for the diffusivity of vapor, I'm writing it using the density of the air and multiplying it with the mass fraction of the vapor to the air [kgmoisture/kgair]. I don't know how to write this term because if I use the C_YI(c,t,i) macro it gives error since I haven't activated the species model (I'm trying to solve the problem using UDS)...any ideas?
Thanks!

[Bruno Machado]

Originally Posted by Boh

Hi!
I need to write an UDf for the diffusivity of vapor, I'm writing it using the density of the air and multiplying it with the mass fraction of the vapor to the air [kgmoisture/kgair]. I don't know how to write this term because if I use the C_YI(c,t,i) macro it gives error since I haven't activated the species model (I'm trying to solve the problem using UDS)...any ideas?
Thanks!

if you are not using species model and using UDS instead, you probably need to save your mass fraction as a UDMI and correct it every iteration.

[Boh]

Thanks for your reply....but I don't understand how I can express the mass fraction in order to save it in UDMI