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Old   June 17, 2017, 12:30
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  #81
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Masoud Ravan
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Quote:
Originally Posted by furqanrk View Post
Have you implemented PBM model with command
> /define/models/addon-module ?
If Yes... There is manual in fluent, very easy and useful !

Good Luck
Thanks for respond,

Actually no, I didn't use PBM yet. I want to learn the concept of this model
I appreciate if anyone knows a reference.
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Old   July 13, 2017, 10:47
Lightbulb invalid data on PBM
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Hi
I am modeling two phase(water-in-oil) multiphase in a tank with Rushton impeller and I face a problem in aggregation and breakage system of my PBM. the problem is that I use discrete method for population balance and I have 7 bins. the bin fractions are not correct. (bin0=.99 and other bins are totally 0.01) I should mention that bin0 is the bin with largest droplet diameter. it seems that breakage doesn't happen in my tank. even I just use breakage without coalescence I saw no change in droplet diameter.
any help will be appreciated
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Old   July 13, 2017, 13:51
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Quote:
Originally Posted by sepehrkhn View Post
Hi
I am modeling two phase(water-in-oil) multiphase in a tank with Rushton impeller and I face a problem in aggregation and breakage system of my PBM. the problem is that I use discrete method for population balance and I have 7 bins. the bin fractions are not correct. (bin0=.99 and other bins are totally 0.01) I should mention that bin0 is the bin with largest droplet diameter. it seems that breakage doesn't happen in my tank. even I just use breakage without coalescence I saw no change in droplet diameter.
any help will be appreciated
Which Kernels are you using for water-in-oil breakup and coalescence?
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Old   July 13, 2017, 14:46
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Quote:
Originally Posted by BlnPhoenix View Post
Which Kernels are you using for water-in-oil breakup and coalescence?
I use Luo model for both with surface tension of 0.02
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Old   July 13, 2017, 23:45
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Quote:
Originally Posted by sepehrkhn View Post
Hi
I am modeling two phase(water-in-oil) multiphase in a tank with Rushton impeller and I face a problem in aggregation and breakage system of my PBM. the problem is that I use discrete method for population balance and I have 7 bins. the bin fractions are not correct. (bin0=.99 and other bins are totally 0.01) I should mention that bin0 is the bin with largest droplet diameter. it seems that breakage doesn't happen in my tank. even I just use breakage without coalescence I saw no change in droplet diameter.
any help will be appreciated
Can you try to use 'LOG NORMAL' values to set your bins value from velocity boundary condition window ?
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Old   July 14, 2017, 12:03
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Quote:
Originally Posted by furqanrk View Post
Can you try to use 'LOG NORMAL' values to set your bins value from velocity boundary condition window ?
I dont have inlet. I just patch a volume of the tank as a secondary phase ant start calculation after. but after the bin0 fraction which is the largest bin starts increasing to 0.99 .
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Old   July 15, 2017, 09:09
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Quote:
Originally Posted by sepehrkhn View Post
Hi
I am modeling two phase(water-in-oil) multiphase in a tank with Rushton impeller and I face a problem in aggregation and breakage system of my PBM. the problem is that I use discrete method for population balance and I have 7 bins. the bin fractions are not correct. (bin0=.99 and other bins are totally 0.01) I should mention that bin0 is the bin with largest droplet diameter. it seems that breakage doesn't happen in my tank. even I just use breakage without coalescence I saw no change in droplet diameter.
any help will be appreciated
How did you set Bins fraction in fluent ? How do you know that one bin should 0.99 and other total is 0.01 to make it equal to 1. Do you have any experimental data ? Or do you have Mean you particle size ? Let assume mean particle size is 0.25 cm and your desire to solve it around 7 bins. so, my suggestion is :

Bins 7
Ratio 1.3
Let asume Min size 0.1 cm ( better to use experimental value )
then set like this:
Fraction
Bin-0 0
Bin-1 0
Bin-2 0
Bin-3 1 ( The mean particle size 0.25cm will the middle one )
Bin-4 0
Bin-5 0
Bin-6 0

Good Luck
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Old   July 15, 2017, 09:45
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Quote:
Originally Posted by furqanrk View Post
How did you set Bins fraction in fluent ? How do you know that one bin should 0.99 and other total is 0.01 to make it equal to 1. Do you have any experimental data ? Or do you have Mean you particle size ? Let assume mean particle size is 0.25 cm and your desire to solve it around 7 bins. so, my suggestion is :

Bins 7
Ratio 1.3
Let asume Min size 0.1 cm ( better to use experimental value )
then set like this:
Fraction
Bin-0 0
Bin-1 0
Bin-2 0
Bin-3 1 ( The mean particle size 0.25cm will the middle one )
Bin-4 0
Bin-5 0
Bin-6 0

Good Luck

thank dude, I model experimental data from another guy... the particle size varies between 50micrometer to 280 micrometer so I use this size in population balance and ratio equal to one.
I patch the volume fraction and I patch bin fractions as follows:
bin0,1,3,4,5,6=0.1
bin2=0.4 because the sauter mean diameter is in this range.
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Old   August 7, 2017, 08:12
Default please help me
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hello everyone
do any one explain the formation of crystal step by step?
secondary phase is my crystal phase and i put the volume fraction zero in boundary condition.
i dont have any computation for secondary phase so this mean that crystal phase is not formatting.
why crystal phase dont form??
could you please help me?
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Old   October 26, 2017, 08:05
Default using file for size distribution in PBM model
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Hey guys,
Do you know how we could specify size distribution for PBM model by using a file in ANSYS FLUENT?
Thanks in Advance,
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Old   October 26, 2017, 11:37
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Quote:
Originally Posted by masoud.ravan View Post
Hey guys,
Do you know how we could specify size distribution for PBM model by using a file in ANSYS FLUENT?
Thanks in Advance,
Population Balance Model > Definition > File > Load File

You need to assign the number of bins before loading the file. The diameters should be ascending, and only one diameter per line! This is the content of a sample file that I used while ago:
Code:
0.0000015
0.000005
0.000029
0.000075
0.000175
0.000375
0.000750
Having the diameters, you can initialize volume fraction of each at inlet/domain.
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Old   December 5, 2017, 10:59
Default Changing discrete method to inhomogeneous method in PBM model
  #92
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Hi everyone
I'm simulating a rectangular duct with velocity inlet and pressure outlet in order to see how water and air (that had been injected from an inlet with each other) separate from each other. I have used the discrete method with 8 bin fractions for solving the population balance equation.
Now I wanna change my method to inhomogeneous and continue the simulation. After adding another phase and defining bin fractions in the third phase, I encounter an error:
================================================== ============================

Node 0: Process 568: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 1: Process 4360: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 2: Process 1952: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 3: Process 3732: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 4: Process 4904: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 5: Process 1448: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 6: Process 3892: Received signal SIGSEGV.

================================================== ============================
MPI Application rank 0 exited before MPI_Finalize() with status 2

The fl process could not be started.

I would be absolutely grateful for your responses...
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Old   December 8, 2017, 11:49
Default
  #93
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Masoud Ravan
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Quote:
Originally Posted by masoud.ravan View Post
Hi everyone
I'm simulating a rectangular duct with velocity inlet and pressure outlet in order to see how water and air (that had been injected from an inlet with each other) separate from each other. I have used the discrete method with 8 bin fractions for solving the population balance equation.
Now I wanna change my method to inhomogeneous and continue the simulation. After adding another phase and defining bin fractions in the third phase, I encounter an error:
================================================== ============================

Node 0: Process 568: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 1: Process 4360: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 2: Process 1952: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 3: Process 3732: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 4: Process 4904: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 5: Process 1448: Received signal SIGSEGV.

================================================== ============================

================================================== ============================

Node 6: Process 3892: Received signal SIGSEGV.

================================================== ============================
MPI Application rank 0 exited before MPI_Finalize() with status 2

The fl process could not be started.

I would be absolutely grateful for your responses...

And I also encountered another problem with the Inhomogeneous method of PBM in AnsysFLUENT.
Do we need special treatment other than enabling aggregation phenomena to make bubbles in a smaller velocity group to go to a bigger velocity group??
I cannot see a transition between velocity groups in my simulations. For instance, when I inject a swarm of bubbles, their diameter would increase till reaching the maximum diameter of their own velocity group and do not go to a bigger velocity group although I have some bigger velocity groups in my problem.
Does anyone have some advice...?
Thanks in advance
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Old   Yesterday, 14:50
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Masoud Ravan
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Hello All!
I am using the Inhomogeneous discrete method in AnsysFluent PBM model. I have two phases and I want to define just one bin for each phase...after setting this condition, phrase "-1.#IND" will be showed in Ratio Exponent and Max Diameter box (as shown in the picture)
Do you know what it means...and is it an error??

Thanks in Advance...
Attached Images
File Type: png -1.#IND.PNG (49.5 KB, 1 views)
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