Learning Forum

[Sayantan Biswas]

Dear All,

I'm working on air-water two fluid system using DPM method. The darg force is implinted via UDF. I want to store the DPM drag force magnitude in a UDMI. What modification it required to store 'drag_force' in an UDMI?

Drag UDF as follow:

# include "udf.h"

# include "dpm.h"

DEFINE_DPM_DRAG(particle_drag_force,Re,p)

{

Thread *t= P_CELL_THREAD(p); /*not sure about this line*/

cell_t c= P_CELL(p); /*not sure about this line*/

real dia, etov;

real adrag, bdrag, cdrag, drag_force;

dia=0.005;  /* bubble diameter */

/* to compute Eotvos Number */

etov=9.81*994.38*(dia*dia)/0.072;

/* to compute the drag coefficient */

adrag=24.0*(1+0.15*pow(Re,0.687))/Re;

bdrag=8.0*etov/(3.0*etov+12.0);

if(adrag>bdrag)

{cdrag=adrag;}

else 

{cdrag=bdrag;}

drag_force=(18.0*cdrag*Re)/24.0; /*this term I want to store in a UDMI*/

C_UDMI(c,t,0)=cdrag;

C_UDMI(c,t,1)=drag_force;

return (drag_force);

}

UDMI requires to access cell and thread, how do I define in DPM simulation?

[Rob]

Are you wanting the DPM effect on the fluid, or the fluid effect on the particle? https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v212/en/flu_udf/flu_udf_sec_define_dpm_body_force.html may give you some hints.

[DrAmine]

Just not use hybrid parallel method and it would work (as hybrid might require some more lines to avoid co-current processes writing in the same memory). I have a feeling you are just using the UDF without really understanding the whole issue: is this correct?