[oball]

Hello, i am using FLUENT DPM to do particle tracking. And for my case, particles need to be considered as trapped when certain conditions satisfied, without ever hit the boundaries. I am now using a UDF to check whether the conditions are satisfied after each DPM time step, but don't know how to tell FLUENT that the particles need to be considered as "trapped" and stop the tracking for that particles. Can anyone know the macro or variables in DPM that i can access in UDF to do this job? Thank you so much!

[upeksa]

It's easy:

DEFINE_DPM_BC(name,p,t,f,f_normal,dim)
{

/*if reflected*/
return PATH_ACTIVE;
/*if trapped*/
return PATH_ABORT;
/*if escaped*/
return PATH_END;

}

You have some examples in your UDF Guide, check it for further information.

Cheers

[oball]

Hi, upeksa,

Thank you for the reply! My problem is the DEFINE_DPM_BC macro will only be executed when the particle center hit the wall boundaries. While for my case, I need to stop the particles before that (when the particle surface hit the wall). I am now using DEFINE_DPM_SCALAR_UPDATE macro to make the judgement (when the particle should be stopped), but do you think we can force FLUENT to execute DEFINE_DPM_BC at a user defined condition? Thank you!!

oball

[upeksa]

I am not sure, I have never used DPM macros that way.

Try something like:

DEFINE_DPM_SCALAR_UPDATE(arguments)
{
/*if I want the particle to stop*/
for (i=0;i<dim;i++)
P_VEL0[i]=0.0;

}

Let me know if it worked.

Cheers

[gearboy]

Originally Posted by oball

Hello, i am using FLUENT DPM to do particle tracking. And for my case, particles need to be considered as trapped when certain conditions satisfied, without ever hit the boundaries. I am now using a UDF to check whether the conditions are satisfied after each DPM time step, but don't know how to tell FLUENT that the particles need to be considered as "trapped" and stop the tracking for that particles. Can anyone know the macro or variables in DPM that i can access in UDF to do this job? Thank you so much!

p->stream_index = -1;

[oball]

Just heard from ANSYS tech service, MARK_PARTICLE(p, P_FL_REMOVED) will work. It will stop the trajectory tracking for that particle and count it as trapped.

[Ebrahim]

Originally Posted by oball

Just heard from ANSYS tech service, MARK_PARTICLE(p, P_FL_REMOVED) will work. It will stop the trajectory tracking for that particle and count it as trapped.

Hello Oball,
Does the above macro work for you? I used it with FLUENT 6.3 but faced with this error:
"error C2065: 'P_FL_REMOVED' : undeclared identifier"
Is it only usable in ANSYS_FLUENT or can be used in FLUENT 6.3 as well?

Thanks

[rdfing]

Originally Posted by oball

Just heard from ANSYS tech service, MARK_PARTICLE(p, P_FL_REMOVED) will work. It will stop the trajectory tracking for that particle and count it as trapped.

I don't see how MARK_PARTICLE(p, P_FL_REMOVED) would be different from p->stream_index = -1

[pakk]

It would be in possible future versions of Fluent where they change the structure of the data, such that p->stream_index is no longer the working.

Even if now "MARK_PARTICLE(p, P_FL_REMOVED)" is a macro that becomes "p->stream_index = -1", it does not have to stay this way. If you want to have more certainty that your code will run in future versions of Fluent, use the interface that the developers give you.