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Old   August 17, 2007, 03:26
Default About bubble diameter setting in multiphase flow
  #1
tchllc
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Hi,everyone,I simulate multiphase flow with eular-eular model.water is continous phase and air is dispersed phase .For the dsepersed phase property,i want to set the bubble diameter is 5mm in inlet zone and 2mm in other zone,the follows is my UDF program,but the simulate result shows that the bubble diameter is 2mm and not 5mm,could anyone be kind to check my program to find where is wrong or give me some good adivses? DEFINE_PROPERTY(bubble_diameter,f,t) {

real d;

begin_f_loop(f,t)

{

if(THREAD_ID(t)==4)/*inlet ID=4*/

d=C_PHASE_DIAMETER(f,t)=0.005;

else

d=C_PHASE_DIAMETER(f,t)=0.002;

}

end_f_loop(f,t)

return d; }
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Old   August 17, 2007, 03:29
Default Re: About bubble diameter setting in multiphase fl
  #2
tchllc
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bubble diameter is 2mm and not 5mm in inlet zone....
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Old   August 17, 2007, 03:56
Default Re: About bubble diameter setting in multiphase fl
  #3
Jack Martinez
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Hi

I am not sure, if you forgot to include it in your UDF mentioned above but you also need to define face, thread and domain pointer in your UDF

so it should be like

DEFINE_PROPERTY(bubble_diameter,f,t)

{

face_t f;

Thread *t;

real dia=0;

Domain *d;

d=Get_Domain(1);

thread_loop_f(t,d)

{

if(THREAD_ID(t)==4)/*inlet ID=4*/

{

begin_f_loop(f,t)

{

dia=C_PHASE_DIAMETER(f,t)=0.005;

}

end_f_loop(f,t) }

else

dia=C_PHASE_DIAMETER(f,4)=0.002;

}

return dia; }

I am too busy to check it myself, moreover, I found your post not properly explained. So check it and if still some problem, feel free to write me a email.

Jack.
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Old   August 17, 2007, 04:48
Default Re: About bubble diameter setting in multiphase fl
  #4
tchllc
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Hi,Jack martinez,

Thank you for your attention of my problem,I just compile your UDF program,but when i set'initialize',The simulation give the erro message as: Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()

Could you check the program to find where is wrong for me? ps:For the gas phase ID is 3,i have change the d=Get_Domain(3)in your program
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Old   August 17, 2007, 08:12
Default Re: About bubble diameter setting in multiphase fl
  #5
tchllc
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Jack Martinez,

I have revised the UDF program as follows, DEFINE_PROPERTY(bubble_diameter,f,t)

{

face_t f;

Thread *t;

real dia=0;

Domain *d;

d=Get_Domain(3);

thread_loop_f(t,d)

{ if(THREAD_ID(t) == 4)/*inlet zone ID=4 */

{

begin_f_loop(f,t)

{ dia=0.005; }

end_f_loop(f,t) }

else

dia=0.002;

}

return dia; } Now,the fluent can simulate,but the result is also bubble diameter as 2mm in inlet zone.
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Old   August 22, 2007, 09:47
Default Re: About bubble diameter setting in multiphase fl
  #6
bashu
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I guess the bubble diameter does not have any meaning on face, try defining it for cells attached to the inlet.
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