Creating an expression for droplet generation frequency

- December 5, 2019 at 10:09 pm
  
  Strong1375
  Subscriber
  
  Hi all,
  
  I am simulating droplet formation process in a 3-D microfluidic flow focusing device. I want to monitor the droplet generation frequency in each of my parametric study, so I need to create an expression for this purpose in order to have it as my output parameter. Unfortunately, I do not really know how to do it. Can anyone help me with this issue? I really need it.
- December 6, 2019 at 8:54 am
  
  Rob
  Ansys Employee
  
  If you look at the results what changes in the model to show a droplet has been formed? Note, you may need to compare monitor graphs rather than a single number.
- December 6, 2019 at 2:44 pm
  
  Strong1375
  Subscriber
  
  Thank you for your reply. I just have done some simulations where I am sure that droplet will be formed by the settings that I have applied to the system. I just want to create an 'expression' for droplet generation frequency in order to find droplets diameter with the f=Q/V formula. Could you please tell me how to define it in cfd-post, if you know?
- December 6, 2019 at 7:31 pm
  
  DrAmine
  Ansys Employee
  
  Add details about the models you are using.
- December 6, 2019 at 7:31 pm
  
  DrAmine
  Ansys Employee
  
  And how the droplets are created in the system : ,by which process.
- December 7, 2019 at 11:35 am
  
  Strong1375
  Subscriber
  
  Thank you for your reply. My system is a simple cross-junction microchannel with 200 um*200 um channel size. My numerical method is Multiphase - VOF, and the droplets are formed by the shear force and drag force applied by the continuous phase on the dispersed phase.
  
  Best,
  
  Hadi
- December 7, 2019 at 12:52 pm
  
  DrAmine
  Ansys Employee
  
  So you want to track the number of droplet?
- December 7, 2019 at 1:07 pm
  
  Strong1375
  Subscriber
  
  Thank you for your reply. Not exactly the number of droplets, I want to know at what frequency the droplets will be formed. I know that I can introduce a point in main channel and sketch the dispersed phase Volume fraction Vs. time and then, use FFT (fast Fourier transform) to find the frequency, but I want to use this frequency for another purpose, such as finding the droplets diameter.
- December 9, 2019 at 6:19 am
  
  DrAmine
  Ansys Employee
  
  Ok. To provide an answer to your question will require more efforts of of the scope of this community.
  You might use the coffee to dpm algorithm to detect lumps without converting them into droplets. Check that.

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