[cardioCFD]

Hi,

I am a bit confused about the use of source coefficients in CFX

I am going to define a source (e.g., momentum) like this:

Sx = K*u
Sy = K*v
Sz = K*w

An estimate for the momentum source coefficient would be: C = dS/du = K. Now my question is this: which of the following CFX setups are correct:

1)
Momentum source X = 1 [kg m^-3 s^-1] * u
Momentum source Y = 1 [kg m^-3 s^-1] * v
Momentum source Z = 1 [kg m^-3 s^-1] * w

Momentum source coefficient = K / 1 [kg m^-3 s^-1]

OR

2)
Momentum source X = K * u
Momentum source Y = K * v
Momentum source Z = K * w

Momentum source coefficient = K / 1 [kg m^-3 s^-1]

I would appreciate any comment on this. Many thanks

[ghorrocks]

2 is correct. Your first comments on how to derive C is correct, so why do you think 1 could be valid?

And don't forget: the coefficient just assists convergence. If you get it wrong it probably won't converge. If you get it right it might converge. It should not affect the actual values of a converged solution.

[cardioCFD]

Thanks a lot Glenn.