Particle momentum source
 

Hi, I am trying to use user function to calculate different forces acting on particles while using lagrangian simulation. As a first step I started by making the example of fortran code routine used to calculate a Schiller-Naumann drag force.

When it calls the subroutine, the following is written:

CALL USER_MOMENTUM_SOURCE (RET(1,1),RET(1,4),RET(1,5), & ARG(1,1),ARG(1,2),ARG(1,5),ARG(1,6), & ARG(1,7),ARG(1,8)) END

SUBROUTINE USER_MOMENTUM_SOURCE (SOURCE,COEF_PT,COEF_FL, & DIAM_PT,VEL_PT,RE_PT,SLPVEL_PT, & DENSITY_FL,VEL_FL)

My first doubt is, does the order of the variables have to match in the statement CALL and the statement SOUBROUTINE? For example, of the 3 return variables in the CALL statement, the source which has 3 components seems to be the second entry while in the SUBROUTINE it seems to be the first entry.

Now on the CFX PRE when it comes to definig the User Defined Function, when I am prompted to introduce the units of the arguments and results, I am not sure if for example the 3 velocity components are to be used I have to write 3 times [m/s].

Finally, according to the example the user created function should be available on the Fluid Pairs form in the Mass and Momentum frame, from the drop-down list. However it wasn´t when I try. Is any step missing?

Thanks,

Alvio