UDF for particle interception with pt_termination fortran routine
 

Hey,

i try to simulate a Filter with a complex geometry. For that I need the Interception of particles. The particles must have a Volume for that (not only being a mass point). The Particle meets the filter a radius before it's mass (middlepoint).This means, that particles get stuck on the filter wall, if they come closer than their radius. I hope you know what I mean.

I think I can realize that with the user fortran routine pt_termination from the Ansys fortran examples.
I first tried it on a sphere (based on a udf here from the forum): thats possible. Here I have die coordinates of the sphere. But for my real geometry I have no coordinates/ can't give it a radius.
Now I had the Idea: can I refer it to the boundary condition of my geometry, The wall of the filter???

For the sphere the code looks:

...
Particle fate : RET(1,1)
C
C Argument variables
C -------------------
C
C Particle mean diameter : ARG(1,1)
C Particle position : ARG(1,2:4)
C Sphere x-position : ARG(1,5)
C Sphere y-position : ARG(1,6)
C Sphere z-position : ARG(1,7)
C
C We know that NLOC is 1 for the particle user source routines!!!!
C================================================= ======================
C
C-----------------------------------------------------------------------
C Calculate the return variables
C-----------------------------------------------------------------------
C
CALL USER_FATE (RET(1,1),ARG(1,1),ARG(1,2),ARG(1,5),ARG(1,6),ARG( 1,7))
C
END

SUBROUTINE USER_FATE (FATE,DIA,PPOS,CPOSX,CPOSY,CPOSZ)
C
C ---------------------------
C Preprocessor includes
C ---------------------------
C
#include "cfd_sysdep.h"
#include "cfd_constants.h"
C
C ------------------------------
C Argument list
C ------------------------------
C
REAL FATE, DIA, PPOS(3), CPOSX, CPOSY, CPOSZ
REAL sphereRAD, PRAD
REAL CONTACT
C
C ------------------------------
C Local variables
C ------------------------------
C
REAL DEAD, ALIVE
C ------------------------------
C Executable statements
C ------------------------------
C
DEAD = 0.
ALIVE = 1.
C
sphereRAD = 0.001
C
C---- Particle starts as alive
C
FATE = ALIVE
C
C---- Calc particle radius
PRAD = ((CPOSX-PPOS(1))**2 + (CPOSY-PPOS(2))**2 + (CPOSZ-PPOS(3))**2)**0.5
CONTACT = sphereRAD - (PRAD - DIA/2.0)
C
C---- Check if user defined criterion was exceeded, stop particle
C --> Set particle mode to __dead__
C
IF (CONTACT.GT.0.0) THEN
FATE = DEAD
ENDIF
C
END





But can I really refer it to the boundary condition. I always get an error. Here is the changed code (the changes are bold):





...
INTEGER NARG, NRET, NLOC
C
CHARACTER*(4) CRESLT
C
REAL ARG(NLOC,NARG), RET(NLOC,NRET)
C
INTEGER IZ(*)
CHARACTER CZ(*)*(1)
DOUBLE PRECISION DZ(*)
LOGICAL LZ(*)
REAL RZ(*)
C
C================================================= ======================
C
C ---------------------------
C Executable Statements
C ---------------------------
C
C================================================= ======================
C
C Return variables:
C -----------------
C
C Particle fate : RET(1,1)
C
C Argument variables
C -------------------
C
C Particle mean diameter : ARG(1,1)
C Particle position : ARG(1,2:4)
C USERREG x-position : ARG(1,5)
C USERREG y-position : ARG(1,6)
C USERREG z-position : ARG(1,7)
C
C We know that NLOC is 1 for the particle user source routines!!!!
C================================================= ======================
C
C-----------------------------------------------------------------------
C Calculate the return variables
C-----------------------------------------------------------------------
C
CALL USER_FATE (RET(1,1),ARG(1,1),ARG(1,2),ARG(1,5),ARG(1,6),ARG( 1,7))
C
END

SUBROUTINE USER_FATE (FATE,DIA,PPOS,CPOSX,CPOSY,CPOSZ)
C
C ---------------------------
C Preprocessor includes
C ---------------------------
C
#include "cfd_sysdep.h"
#include "cfd_constants.h"
C
C ------------------------------
C Argument list
C ------------------------------
C
REAL FATE, DIA, PPOS(3), CPOSX, CPOSY, CPOSZ
REAL USERREG, PRAD
REAL CONTACT
C
C ------------------------------
C Local variables
C ------------------------------
C
REAL DEAD, ALIVE
C ------------------------------
C Executable statements
C ------------------------------
C
DEAD = 0.
ALIVE = 1.

C USERREG = area@Wall
C---- Particle starts as alive
C
FATE = ALIVE
C
C---- Calc particle radius
PRAD = ((CPOSX-PPOS(1))**2 + (CPOSY-PPOS(2))**2 + (CPOSZ-PPOS(3))**2)**0.5
CONTACT = USERREG-(PRAD-DIA/2.0)
C
C---- Check if user defined criterion was exceeded, stop particle
C --> Set particle mode to __dead__
C
IF (CONTACT.GT.0.0) THEN
FATE = DEAD
ENDIF
C
END



Do you know where my mistake is, if it would be possible?

Thank you very much for your help.

USERREG is unset, i.e. it is not initialized or evaluated anywhere in the shown code.

Is that not enough? "USERREG = area@Wall"

What and where would you write? And do you think its possible to refer it to the wall?

The line is commented out, and the syntax is invalid anyways.

Oh yes, you're right. Thank you very much.

hm...how else can I write it? Only 'Wall'...areaAve()@Wall...!?!
I have to say 'wall' is my boundary called in the setup.

I'm Sorry, but I didn't find the solution yet.
How can I write instead of sphereRad (see the part of the user Fortran)

C
DEAD = 0.
ALIVE = 1.
C
sphereRAD = 0.001
C
C---- Particle starts as alive
C
FATE = ALIVE
C
C---- Calc particle radius
PRAD = ((CPOSX-PPOS(1))**2 + (CPOSY-PPOS(2))**2 + (CPOSZ-PPOS(3))**2)**0.5
CONTACT = sphereRAD - (PRAD - DIA/2.0)
C


The Problem is, I have no Geometry like a cylinder, thats why I have no Radius. Is it possible to refer it to the boundary condition, the wall of the Filter? What is a valid syntax for that?
Thank you for your help!

hey,
did you have a udf for interception part?