# Population Balance Modeling (PBM) - Ansys Fluent

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March 15, 2016, 11:41
#41
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Muhammad Furqan Ali
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Quote:
 Originally Posted by chittipo Dear Members, If you have any specific questions on PBM implementation please post here. I will try to answer them, as I gained some experience in it. on - Existing module (or) - Implementation through UDF
Respected experts,

When applying Discrete*Population Balance Model in ANSYS Fluent we have to put predefine boundary conditions values. For Example,

phase.. Air.. Bins...7 Ratio Exponent...1.7 Minimum Dia...0.05cm then in boundary conditions... Velocity Inlet...Boundary Values*for setting*are..

Bin-0-fraction________ * Constant

Bin-1-fraction_________ Constant

Bin-2-fraction_________Constant

Bin-3-fraction_________Constant

Bin-4-fraction_________Constant

Bin-5-fraction_________Constant

Bin-6-fraction_________Constant

How to set these values to get appropriate gas distribution ?

How to set boundary condition values in Fluent Population Balance model ? - ResearchGate. Available from: https://www.researchgate.net/post/Ho..._Balance_model [accessed Mar 15, 2016].

March 15, 2016, 11:48
#42
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Muhammad Furqan Ali
Join Date: Oct 2014
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Quote:
 Originally Posted by chittipo Dear Members, If you have any specific questions on PBM implementation please post here. I will try to answer them, as I gained some experience in it. on - Existing module (or) - Implementation through UDF
Respected experts,

When applying Discrete*Population Balance Model in ANSYS Fluent we have to put predefine boundary conditions values. For Example,

phase.. Air.. Bins...7 Ratio Exponent...1.7 Minimum Dia...0.05cm then in boundary conditions... Velocity Inlet...Boundary Values*for setting*are..

Bin-0-fraction________ * Constant

Bin-1-fraction_________ Constant

Bin-2-fraction_________Constant

Bin-3-fraction_________Constant

Bin-4-fraction_________Constant

Bin-5-fraction_________Constant

Bin-6-fraction_________Constant

How to set these values to get appropriate gas distribution ?

How to set boundary condition values in Fluent Population Balance model ? - ResearchGate. Available from: https://www.researchgate.net/post/Ho..._Balance_model [accessed Mar 15, 2016].

March 15, 2016, 11:57
#43
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Muhammad Furqan Ali
Join Date: Oct 2014
Location: beijing
Posts: 53
Rep Power: 5
Quote:
 Originally Posted by chittipo Could you clarify more on your problem. 1) What method you are using to solve the PBE ?
Respected experts,

When applying Discrete*Population Balance Model in ANSYS Fluent we have to put predefine boundary conditions values. For Example,

phase.. Air.. Bins...7 Ratio Exponent...1.7 Minimum Dia...0.05cm then in boundary conditions... Velocity Inlet...Boundary Values*for setting*are..

Bin-0-fraction________ * Constant

Bin-1-fraction_________ Constant

Bin-2-fraction_________Constant

Bin-3-fraction_________Constant

Bin-4-fraction_________Constant

Bin-5-fraction_________Constant

Bin-6-fraction_________Constant

How to set these values to get appropriate gas distribution ?

How to set boundary condition values in Fluent Population Balance model ? - ResearchGate. Available from: https://www.researchgate.net/post/Ho..._Balance_model [accessed Mar 16, 2016].

April 6, 2016, 04:06
#44
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Muhammad Furqan Ali
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Quote:
 Originally Posted by chittipo Dear Members, If you have any specific questions on PBM implementation please post here. I will try to answer them, as I gained some experience in it. on - Existing module (or) - Implementation through UDF
Hi experts..

In a bubble column reactor two fluid air/ water is used. From the experiments and literature survey we*came to know the Mean Diameter is 4mm. Almost all previous researchers set 4mm air bubble diameter at INLET of bubble column. Here, We are using PBM too. For CFD-PBM coupling we have 10 classes of different size distributions. We applied Eu-Eu two phase models. Any guidances would be highly appreciated to tell how to set 4mm air bubble dia at INLET ?

Regards

How to set 4mm Initial Diameter of air bubble in Ansys Fluent ? - ResearchGate. Available from: https://www.researchgate.net/post/Ho...n_Ansys_Fluent [accessed Apr 6, 2016].

April 6, 2016, 04:32
#45
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Quote:
 Originally Posted by furqanrk Hi experts.. In a bubble column reactor two fluid air/ water is used. From the experiments and literature survey we*came to know the Mean Diameter is 4mm. Almost all previous researchers set 4mm air bubble diameter at INLET of bubble column. Here, We are using PBM too. For CFD-PBM coupling we have 10 classes of different size distributions. We applied Eu-Eu two phase models. Any guidances would be highly appreciated to tell how to set 4mm air bubble dia at INLET ? Regards How to set 4mm Initial Diameter of air bubble in Ansys Fluent ? - ResearchGate. Available from: https://www.researchgate.net/post/Ho...n_Ansys_Fluent [accessed Apr 6, 2016].
I think, based on your Classes [10], 4 mm falls under which bin (class)? let us assume it is 4th bin. then in 0-9 bins, Bin-3-fraction is 1 at inlet and remaining 0. (I left working with PBM 3 years ago, there might have been number of changes in Fluent by now. please note my answer is based on my understanding of Fluent 3 years ago.)

April 6, 2016, 04:57
#46
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Muhammad Furqan Ali
Join Date: Oct 2014
Location: beijing
Posts: 53
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Quote:
 Originally Posted by chittipo Dear Members, If you have any specific questions on PBM implementation please post here. I will try to answer them, as I gained some experience in it. on - Existing module (or) - Implementation through UDF
Quote:
 Originally Posted by chittipo I think, based on your Classes [10], 4 mm falls under which bin (class)? let us assume it is 4th bin. then in 0-9 bins, Bin-3-fraction is 1 at inlet and remaining 0. (I left working with PBM 3 years ago, there might have been number of changes in Fluent by now. please note my answer is based on my understanding of Fluent 3 years ago.)
ohh thank you sir, as your assumption 4th bin is for 4mm. So, 4th Bin would be ( Bin-4-fraction ) zero. NOT Bin-3-fraction. ( May be there is typing error ). Do you know.. I was following the same procedure, Because from one manual I got the same hint. but unfortunately, Whenever I put Bin-4-fraction value 1 and all other remain zero. there would be a floating point exception error. Although, I also mark a region same as Inlet and Patch Bin-4-fraction value 1. But same floating point exception error because of all bins are zero except Bin-4-fraction.
Error is :
Divergence detected in AMG solver: bin-2-fraction
Divergence detected in AMG solver: bin-3-fraction
Divergence detected in AMG solver: bin-4-fraction
Divergence detected in AMG solver: bin-5-fraction
Divergence detected in AMG solver: bin-6-fraction
Divergence detected in AMG solver: bin-7-fraction
Divergence detected in AMG solver: bin-8-fraction
Divergence detected in AMG solver: bin-9-fraction
Divergence detected in AMG solver: bin-2-fraction
Divergence detected in AMG solver: bin-3-fraction
Divergence detected in AMG solver: bin-4-fraction
Divergence detected in AMG solver: bin-5-fraction
Divergence detected in AMG solver: bin-6-fraction
Divergence detected in AMG solver: bin-7-fraction
Divergence detected in AMG solver: bin-8-fraction
Divergence detected in AMG solver: bin-9-fraction
Divergence detected in AMG solver: bin-2-fraction
Divergence detected in AMG solver: bin-3-fraction
Divergence detected in AMG solver: bin-4-fraction
Divergence detected in AMG solver: bin-5-fraction
Divergence detected in AMG solver: bin-6-fraction
Divergence detected in AMG solver: bin-7-fraction
Divergence detected in AMG solver: bin-8-fraction
Divergence detected in AMG solver: bin-9-fraction
turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 10690 cells

Error at Node 0: floating point exception

Error at Node 2: floating point exception

April 6, 2016, 05:02
#47
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Quote:
 Originally Posted by furqanrk ohh thank you sir, as your assumption 4th bin is for 4mm. So, 4th Bin would be ( Bin-4-fraction ) zero. NOT Bin-3-fraction. ( May be there is typing error ). Do you know.. I was following the same procedure, Because from one manual I got the same hint. but unfortunately, Whenever I put Bin-4-fraction value 1 and all other remain zero. there would be a floating point exception error. Although, I also mark a region same as Inlet and Patch Bin-4-fraction value 1. But same floating point exception error because of all bins are zero except Bin-4-fraction. Error is : Divergence detected in AMG solver: bin-2-fraction Divergence detected in AMG solver: bin-3-fraction Divergence detected in AMG solver: bin-4-fraction Divergence detected in AMG solver: bin-5-fraction Divergence detected in AMG solver: bin-6-fraction Divergence detected in AMG solver: bin-7-fraction Divergence detected in AMG solver: bin-8-fraction Divergence detected in AMG solver: bin-9-fraction Divergence detected in AMG solver: bin-2-fraction Divergence detected in AMG solver: bin-3-fraction Divergence detected in AMG solver: bin-4-fraction Divergence detected in AMG solver: bin-5-fraction Divergence detected in AMG solver: bin-6-fraction Divergence detected in AMG solver: bin-7-fraction Divergence detected in AMG solver: bin-8-fraction Divergence detected in AMG solver: bin-9-fraction Divergence detected in AMG solver: bin-2-fraction Divergence detected in AMG solver: bin-3-fraction Divergence detected in AMG solver: bin-4-fraction Divergence detected in AMG solver: bin-5-fraction Divergence detected in AMG solver: bin-6-fraction Divergence detected in AMG solver: bin-7-fraction Divergence detected in AMG solver: bin-8-fraction Divergence detected in AMG solver: bin-9-fraction turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 10690 cells Error at Node 0: floating point exception Error at Node 2: floating point exception
No, it is not the assumption. based on your min/max diameter and the geometric ratio. 4 mm falls on which bin? you should adjust min/max in such a way that there is 4 mm Class in 10 classes.

April 6, 2016, 05:04
#48
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Muhammad Furqan Ali
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Quote:
 Originally Posted by chittipo No, it is not the assumption. based on your min/max diameter and the geometric ratio. 4 mm falls on which bin? you should adjust min/max in such a way that there is 4 mm Class in 10 classes.
Respected Sir, That BIN is 2nd bin., 4mm falls in 2nd class...

April 6, 2016, 05:17
#49
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Quote:
 Originally Posted by furqanrk Respected Sir, That BIN is 2nd bin., 4mm falls in 2nd class...
There could be several reasons for Divergence.

1. Check all BCs
2. Check initial condition
3. Check time step

4. Lean down the model. for e.g. do not activate nucleation, growth, agg, coalescence etc. just run the case from inlet conditions. Finally u should see no change in bubble size but 4 mm is spread in your domain based on flow. you can also reduce the classes to 5 may be first. no to turbulence. no to any complex process. just check the flow.

4. Step by step activate each phenomena

5. Check solver settings URF etc...

it is important to run the model step by step and go forward to complete the model.

April 6, 2016, 05:27
#50
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Muhammad Furqan Ali
Join Date: Oct 2014
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Quote:
 Originally Posted by chittipo There could be several reasons for Divergence. 1. Check all BCs 2. Check initial condition 3. Check time step 4. Lean down the model. for e.g. do not activate nucleation, growth, agg, coalescence etc. just run the case from inlet conditions. Finally u should see no change in bubble size but 4 mm is spread in your domain based on flow. you can also reduce the classes to 5 may be first. no to turbulence. no to any complex process. just check the flow. 4. Step by step activate each phenomena 5. Check solver settings URF etc... it is important to run the model step by step and go forward to complete the model.
Thank you very much sir..

 May 29, 2016, 06:18 #51 New Member   rahgoshafan Join Date: Jul 2009 Posts: 9 Rep Power: 10 Hello All I need simulation PBM in vessel mixture but i don't define PBM please help me with example file

May 30, 2016, 02:02
#52
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Muhammad Furqan Ali
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Quote:
 Originally Posted by rahgoshafan Hello All I need simulation PBM in vessel mixture but i don't define PBM please help me with example file
hi , rahgoshafan,
What do you mean define ?

 May 30, 2016, 09:10 hi every body #53 New Member   fati Join Date: May 2016 Posts: 3 Rep Power: 3 in my simulation, I should calculated the electric field intensity and so computing aggregation rate with writing udf in pbm model, becouse the electric field causes agregation. can I compute the electric field intensity with mhd model? and in writing udf,I do not need to calculate the field through the writing udf? thanks

 May 31, 2016, 11:36 #54 New Member   fati Join Date: May 2016 Posts: 3 Rep Power: 3 hi friends I'm elementry in writing udf. can anyone help me to writing udf for aggregation rate, couse the electric field with AC flow in population balance model ? the equations for Ac field are available. thank Last edited by fatia; June 1, 2016 at 06:27.

 June 2, 2016, 09:44 #55 New Member   rahgoshafan Join Date: Jul 2009 Posts: 9 Rep Power: 10 Hi furqanrk I need help for define udf code for any model i need see sample file in fluent. i read any time PBM manual but don't learn how make pbm model

June 3, 2016, 11:45
#56
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Muhammad Furqan Ali
Join Date: Oct 2014
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Quote:
 Originally Posted by rahgoshafan Hi furqanrk I need help for define udf code for any model i need see sample file in fluent. i read any time PBM manual but don't learn how make pbm model
sorry, I do not have any idea about it.

 June 21, 2016, 13:50 #57 New Member   rahgoshafan Join Date: Jul 2009 Posts: 9 Rep Power: 10 Hi All I need tutorial for step of config and solve Population Balance Model . Thanks for help email is: rahgoshafan@yahoo.com

 July 18, 2016, 12:18 #58 New Member   n kh Join Date: Jan 2013 Posts: 6 Rep Power: 6 hi every one i am trying to use pbm in fluent, and my fluent version is not licensed unfortunately.... how can i enable pbm in my fluent? thanks

July 19, 2016, 08:18
#59
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Muhammad Furqan Ali
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Quote:
 Originally Posted by hypotalamoos hi every one i am trying to use pbm in fluent, and my fluent version is not licensed unfortunately.... how can i enable pbm in my fluent? thanks
With the reference to PBM Manual( ANSYS User Guide )...
The population balance module is loaded into ANSYS Fluent through the text user interface (TUI). The module can only be loaded when a valid ANSYS Fluent case file has been set or read. The text command to load the module is:

define → models → addon-module

A list of ANSYS Fluent add-on modules is displayed:

> /define/models/addon-module
Fluent Addon Modules:
0. None
1. MHD Model
2. Fiber Model
3. Fuel Cell and Electrolysis Model
4. SOFC Model with Unresolved Electrolyte
5. Population Balance Model
6. Adjoint Solver
7. Single-Potential Battery Model
8. Dual-Potential MSMD Battery Model
Enter Module Number: [0] 5
Select the Population Balance Model by entering the module number 5. During the loading process a scheme library containing the graphical and text user interface, and a UDF library containing a set of user defined functions are loaded into ANSYS Fluent. A message Addon Module: popbal...loaded! is displayed at the end of the loading process.
Best of Luck

July 19, 2016, 08:39
#60
New Member

adnan
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Quote:
 Originally Posted by AlphaKapla You should expect a max diameter in order to have your Particle Size Distribution fully defined in that range. In other words, you have to define a range that even if you make it bigger, the result will not be different. For example, I am actually using this following range : [2.4e-10m;8e-6m], for nucleation/growth/coagulation of carbon particles.
How to write the UDF for DPM drag. I tried to write the UDF for DPM-Gidaspow drag model but it did not work properly. Any one can help me where I am wrong. Any help will be appreciated. Below is my UDF

#include "udf.h"
#include "dpm.h"
#define ZERO 0.0000001

DEFINE_DPM_DRAG(dpm_gidaspow_drag,Re,p)
{
Thread *thread_g, *thread_s, *mix_thread;
real x_vel_g, x_vel_s, y_vel_g, y_vel_s, abs_v, slip_x, slip_y,
rho_g, rho_s, mu_g, dp, reyp, reyp1,void_g, void_s, cd, D;
cell_t cell;
real left_term;
real dragcoefficient;

/*find the cell index and thread of the cell that the particle is currently in*/
cell=P_CELL_THREAD(p);
mix_thread=THREAD_SUB_THREAD(P_CELL_THREAD(p),0);

/* find the threads for the gas (primary) */

thread_g = THREAD_SUB_THREAD(mix_thread,0);/* gas phase thread */
thread_s = THREAD_SUB_THREAD(mix_thread,1);/* solid phase thread */
/* find phase velocities and properties*/

x_vel_g = C_U(cell, thread_g);
y_vel_g = C_V(cell, thread_g);

x_vel_s=P_VEL(p)[0];
y_vel_s=P_VEL(p)[1];

slip_x = x_vel_g - x_vel_s;
slip_y = y_vel_g - y_vel_s;

rho_g = C_R(cell, thread_g); /*density*/
rho_s =P_RHO(p);

mu_g = C_MU_L(cell, thread_g); /*laminar viscosity*/

dp =P_DIAM(p);

/*compute slip*/
abs_v = sqrt(slip_x*slip_x + slip_y*slip_y); /*absolute value of slip velocity*/

void_g = C_VOF(cell, thread_g);/* gas vol frac*/

Message ("Voidage of gas phase %f \n", void_g);

void_s = 1-void_g;/*particle vol frac*/

/*compute reynolds number*/
reyp =rho_g*abs_v*dp/mu_g; /*no volume fraction???*/
reyp1 = void_g*reyp;

if(reyp1<1000)
cd=24/reyp1*(1+0.15*pow(reyp1,0.687));
else
cd = 0.44;
if (void_g <=0.8)
{
/* Ergun Drag Model */
D = 150.0*void_s*void_s*mu_g/void_g/dp/dp+1.75*void_s*rho_g*abs_v/dp;
}
else
{
/* Wen & Yu Model */
D = 0.75*cd*void_g*void_s*rho_g*abs_v/dp/pow(void_g,2.65);
}

left_term=rho_s*pow(dp,2)/mu_g;
dragcoefficient=left_term*D/(abs_v+ZERO);
return dragcoefficient;

}

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