Understanding multiphase modeling (VOF) - Part 1

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  • Опубліковано 7 лис 2024

КОМЕНТАРІ • 138

  • @andremartins8384
    @andremartins8384 4 роки тому +1

    Dear József, sincere thanks for sharing this video with us! I'm very excited about learning OpenFoam and your videos are awesome, best regards from Brazil!

  • @edwardvasquezmorales2028
    @edwardvasquezmorales2028 7 років тому +6

    Bien Jozsef, felicitaciones y gracias. Un saludo desde Perú.

  • @nikhilbhamare6761
    @nikhilbhamare6761 4 роки тому

    Yes sir yes. Magical water column.
    I really like your videos. 👌🏻👍🏻😄

  • @gordonfreeman7775
    @gordonfreeman7775 3 місяці тому

    Thank you very much for the amazing tutorial videos!!
    I just wanted to know how do we interpret the alpha values between 0 and 1. If the alpha value is say 0.05 at a location, does it mean that there is mist present there? As in is the simulation predicting there are small liquid droplets in the vapor at that location? Or do we interpret it as approximately 0 hence fully vapor?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  3 місяці тому

      It is a numerical value. Has nothing to do with reality. This is why the number of these cells should be kept to a minimum.

    • @gordonfreeman7775
      @gordonfreeman7775 3 місяці тому

      @@OpenFOAMJozsefNagy Thank you for your response!! Which method would you recommend if one is interested in knowing how much liquid is carried over/entrained in the gas phase in form of mist or droplets?

  • @jayangasamarasinghe4053
    @jayangasamarasinghe4053 2 роки тому

    Thank you very much for the descriptive tutorial. Could you please let us know how to change/ generate Alpha.water file.

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  2 роки тому

      I don't understand. Do you mean in which editor? In which way?

  • @shehabsalem-ho3bx
    @shehabsalem-ho3bx Рік тому

    Thank you very much for the descriptive tutorial. Could you please let us know how to change from Newtonian to non-Newtonian?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  Рік тому

      Change the entry from Newtonian to e.g. powerLaw and specify the coefficients.

  • @MedoZamalek1911
    @MedoZamalek1911 5 років тому +1

    thank you sir for this very useful tutorial .. i faced a problem that i couldnt get the different density of the water column and it is zero over the entire domain and i executed setFields line!!

  • @damonlee8135
    @damonlee8135 9 років тому

    Thank you very much for such a detailed tutorial!

  • @yusufpolat13
    @yusufpolat13 2 роки тому

    Good work Man...

  • @letstravelsomewhere
    @letstravelsomewhere 5 років тому +1

    I need to design Pipeline inspection Gauge for my final year - am i in the right track ?

  • @zengchensun2628
    @zengchensun2628 3 роки тому +1

    Hi sir. What is the 2S means in momentum equation?

  • @pacoespi
    @pacoespi 4 роки тому

    Hi. Thanks for your video. It is very useful. Just one question: Can you please explain the difference between p and p_rgh, and how are both related and calculated?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  4 роки тому +1

      p is the sum of p_rgh and the rho*g*h. So p_rgh is only the dynamic part of the pressure.

    • @pacoespi
      @pacoespi 4 роки тому

      @@OpenFOAMJozsefNagy Hi. Thanks. So I should be able to obtain the pressure as P = rho * (g*h + 0.5*u^2) ? I ask since I tried this already with post-processed data and the results were not the same.

  • @drjuanenrique
    @drjuanenrique 10 років тому

    József, thank you very much too...

  • @balapesar
    @balapesar 9 років тому

    Dear Jozsef
    Greetings,
    Thanks for your interesting videos.
    I need to model a collision between a solid particle and a falling droplet. Based on existing experimental results after collision, particle start penetrating into droplet and create a very thin liquid film in shape of a hallow truncated cone around particle which is called lamella (whole the collision and lamella formation happens very fast ~ 1 ms)
    My alternative softwares for simulation are Fluent, OpenFoam, Comsol and Gerris. I'd like to get a piece of advice from you to know which of these softwares is more suitable for simulating this phenomenon (i.e. is able to predict lamella formation and its geometry more accurately)
    Here is some complementary information:
    - Droplet diameter is 2.8 mm and particle diameter is 2.0 mm
    - Droplet is falling by gravity and its velocity at collision is 0.8 m/s
    - Particle is moving horizontally with 8.0 m/s
    - Drop is water and particle density is 1050 kg/m3
    I'm looking forward to hearing your helpful comments.
    Many thanks,

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      Sayed Hossein Banitabaei I have no experience whatsoever with Comsol or Gerris. I guess OpenFOAM and Fluent are rather similar, you will need VOF for your case. You will need a dynamic mesh refinement (available in OpenFOAM). Just try the damn break tutorial with mesh refinement and modify it to your needs. I guess your simulation will run for a while.

    • @balapesar
      @balapesar 9 років тому

      Dear József,
      Thanks for your reply.
      Since I do not have any experience for using
      "dynamic mesh refinement", would you please let me know at least one tutorial in each of the following subjects that can help me more in modeling droplet-particle collision:
      - VOF
      - Dynamic mesh refinement
      Your advice is really helpful and appreciated. My email address is: h.banitabaei@gmail.com
      in case you can send any helpful document.

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      Sayed Hossein Banitabaei Check out the tutorials in OpenFOAM/OpenFOAM-2.3.0/tutorials/multiphase/interDyMFoam. If you are using another version than your path will be of course different to the tutorials. Take a look at constant/dynamicMeshDict within the cases. The magic happens there.

  • @sandipgewali641
    @sandipgewali641 2 роки тому

    After running the setFields utility, nano/gedit can't open the 0/alpha.water file. Despite that, I can see the water column in paraview. Still, why can not the nano/gedit read the 0/alpha.water file ?? It can't display the list of values of alphas for various cells. Instead the list seems cryptic with just "@" signs over there. The rest of the boundary conditions stay the same.

  • @sumitzanje5207
    @sumitzanje5207 5 років тому

    Hi I'm trying to solve two phase flow case.
    Case description: A horizontal pipe filled with water. From upstream end of the pipe say at a certain distance there is air tank supplying air into the horizontal pipe. I want to introduce the air with specific constant pressure and some desired volume. I want to push all the air from my tank into the horizontal pipe so that I can later quantify my results accurately (knowing exact volume used in different case files). The problem is to simulate this case i was trying to introduce a tank geometry on above horizontal pipe which was connected to air tank with one small vertical pipe. But as air has low density all air is not entering into the horizontal pipe (some on the top portion on tank, though air pressure is high initially). So Later I changed ma geometry and made tank below horizontal pipe. This allows complete air to get into the horizontal channel but now water is entering into the air tank and hence I'm not utilizing initial water volume used in the simulatiopn which is later very important for quantification of results.
    Is there any boundary condition I can use which just allow specific volume of air (time controlled air inlet) so that after certain volume or time that boundary not supplying any air into the horizontal pipe, something like this?
    Please let me know whats are the possible solutions.

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  5 років тому

      Did you try the uniformFixedValue BC? There you can specify a csv file with time dependent data.

  • @joshmccraney4020
    @joshmccraney4020 2 роки тому +1

    Kind of a general question here, but is there a way to run interFoam until it reaches steady state and then run setFields again? I'll happily donate if you have a technique (I have before and will again).

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  2 роки тому +1

      Dear Josh, do you mean automatically or manually? Manually you can use a function object, which monitors the mean value of alpha in the volume and once you see, that the value is constant, you can stop the simulation and execute setFields. For the automatic version some kind of script or app could do the same, but this wold have to be set up.

    • @joshmccraney4020
      @joshmccraney4020 2 роки тому

      @@OpenFOAMJozsefNagy This is what I tried but no luck. My controlDict specifies to startFrom latestTime. Then my setFieldsDict only specifies regions, which I make a different phase and a given value. So I begin the simulation as normal, stop it at some time, execute setFields with a different value than what was initialized, then execute interFoam. The simulation continues from the previous time but no change is made to the liquid/gas field. I'm using OF6

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  2 роки тому +1

      @@joshmccraney4020 I think possibly if you start a new case with 0 then it should work.

    • @joshmccraney4020
      @joshmccraney4020 2 роки тому

      @@OpenFOAMJozsefNagy A new case with 0? You mean recomposePar and then rename the latest time folder 0? I did get it working with funkySetFields tho, which is nice!

  • @saketh79
    @saketh79 6 років тому +1

    I have a problem in loading alpha.water values in paraview. I am seeing only 0 assigned to all points(including the box). But inside the file i see that 1 being assigned to points in the box and 0 to remaining points outside the box. I tried twice with setfields but it didnt work. Am I doing something wrong?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому +3

      Paraview is confused by your orig file. Move it out of 0 and you will see alpha.

  • @sumitzanje5207
    @sumitzanje5207 5 років тому

    How to calculate the void fraction for a pipe flow over time? Basically I want to plot "Time Vs. Void fraction" for a pipe carrying bubbly flow. I'm focusing on one particular section and want to determine void fraction in that section and how it changes over the time as bubbly flow is passing through it.

  • @DpointW
    @DpointW 5 років тому

    Hi,
    I have a short and probably quite simple question about the presentation of the results of interFoam in Paraview.
    So there are two phases, air and water. To view only the water in Paraview, I use the clip function in conjunction with scalar and set the alpha value to 0.5. What I haven't quite understood yet is what this value stands for? Does this mean that all cells containing at least 50% water are displayed?
    In simulations with a finer grid, areas were also displayed in which there was no water according to the coarser grid.
    Or is this a clear indication that my grid is too coarse?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  5 років тому +1

      This is a drawback of the VOF method. Your questions are valid and usually there should be only one cell with 0.5 representing the surface, however due to numerics it is possible to have a smeared out surface. This is unphysical of course. You really have to make a compromise between resolution and run-time. This is also true for all commercial codes, this is not an OpenFOAM specific problem.

  • @samahbendada6
    @samahbendada6 5 років тому +1

    Hello.
    I am new at Open Foam.
    I tried to run this system and i did all of your steps, but I dont know why the alpha is zero at all time steps.
    I would appreciate your help in this problem.

  • @007aha1
    @007aha1 4 роки тому +2

    to summarize this tutorial: "we dont talk about this"

  • @DaylightDigital
    @DaylightDigital 9 років тому +2

    In the final VOF equation, what is u_r? What velocity is being referenced here?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому +4

      This is the velocity, which is used for interface compression. Details can be found in the phd thesis of Henrik Rusche.

    • @ntm90
      @ntm90 9 років тому +6

      u_r is the relative velocity betwen the two phases.
      u_r = u_liquid - u_gas

  • @prakashachandrasahoo4618
    @prakashachandrasahoo4618 3 роки тому

    Dear sir, how to calculate impact velocity of water droplet impacting on solid surface in Ansys fluent and what is range value of that droplet velocity?

  • @avinashkumarverma7675
    @avinashkumarverma7675 3 роки тому

    after executing setFields command it is showing FOAM warning and no list of alpha values is appearing as you have shown in this video. What might the problem? Can you please explain? I have followed this tutorial of yours step by step.

  • @ValenciaaaaaT
    @ValenciaaaaaT 4 роки тому

    Hi Jozsef, great video! I encountered a problem when executing setFields: it says that 'Field alpha.water is not found.' but i followed the steps correctly. Could i get some help?

  • @ΝάσοςΜπαλαχτσής
    @ΝάσοςΜπαλαχτσής 3 роки тому

    Hello! Nice video! I have completed a simulation where i get alpha vs time. How can I get volume vs time?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  3 роки тому

      Use the integrate variables filter.

    • @ΝάσοςΜπαλαχτσής
      @ΝάσοςΜπαλαχτσής 3 роки тому

      @@OpenFOAMJozsefNagy Thanks a lot! One more question. Can you explain the reason why the integration of alpha gives the volume?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  3 роки тому

      @@ΝάσοςΜπαλαχτσής Because the function calculates the volume integral of the cells filled by alpha.

  • @prakashachandrasahoo4618
    @prakashachandrasahoo4618 3 роки тому

    What is the procedure to calculate that impact velocity of droplet in numerical method?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  3 роки тому

      You can start with the velocity field and the alpha field.

  • @school771
    @school771 9 років тому

    Hello I am tried to simulate two phase stratified (air-water) flow using VOF model with ANSYS FLUENT are you familiar with VOF model in ANSYS FLUENT code?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      No, I'm sorry, I am not familiar. I guess it will be simliar to that of OpneFOAM, but I cannot guarantee it.

  • @haivandang4831
    @haivandang4831 5 років тому

    I can do most of the video. but in final stage, after coding foam.foam. I cannot open foam.foam in paraview. Please let me know. Thank you for your support

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  5 років тому

      It is just a simple text file with the ending ".foam" . Nothing special.

  • @blind-tr1my
    @blind-tr1my 6 років тому

    Awesome videoes sir.....!!.
    Can u also do particle tracking in OpenFOAM?
    thanks

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому +1

      That is unfortunately one of the few topics I am not so familiar with. Sorry.

  • @sushmajyothirmai2586
    @sushmajyothirmai2586 3 роки тому

    sir , can we use this model to simulate gas-solid flow (two phase)??

  • @raulgrunewald4055
    @raulgrunewald4055 6 років тому

    where did you collect the interFoam information that you show here from? I mean, is there an article or some official paper that explains in detail how interFoam works? or maybe some description of OpenFOAM about interFoam?

  • @manas8603
    @manas8603 3 роки тому

    what's the difference between 0.orig and 0 , thanks

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  3 роки тому

      .orig is just a backup folder and is igrnored by the solver.

  • @DrMikeFoster
    @DrMikeFoster 9 років тому

    Thank you for your work on this...very helpful. When I try to view the scalar contour, it only shows values of 0. I finally figured out that Paraview was reading alpha.water .org instead of alpha.water. As a fix, I just put the .org file somewhere else. Is there a way to tell Paraview to just use the non-.org file in the future?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      If I understand your question correctly, paraview automatically selects alpha.water.org and you delete it, so it selects alpha.water instead. If you click Contour in Paraview, you will find under Properties "Contour By" and there you can select all your scalarFields.

    • @DrMikeFoster
      @DrMikeFoster 9 років тому

      Yes, once alpha.water.org is removed from the 0 folder, Paraview picks up alpha.water just fine. It seemed like when you went through, both alpha.water and alpha.water.org were both in the 0 folder, and Paraview picked up alpha.water instead of alpha.water.org. Do you know why it did that in your case?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      Mike Foster
      As I mentioned, did you try and select alpha.water?

    • @DrMikeFoster
      @DrMikeFoster 9 років тому

      József Nagy If alpha.water and alpha.water.org are in the 0 folder, when I open foam.foam in Paraview all I see are values of 0 for the domain. If I then click on Contour, see that Contour By: alpha.water (and the Value Range shows only 0), and then click on Apply, the domain disappears from the graphics window. If I click on the eye icon next to foam.foam in the tree, the domain shows again. When I then click on Contour1 underneath it, I don't see any changes.

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      Mike Foster
      Well that's odd. I'm sorry, but It's difficult to solve the problem over youtube. Send me a screenshot to the mail adress, that you find in my about section!

  • @ChaitanyaArige
    @ChaitanyaArige 8 років тому

    Thank you very much Sir.

  • @rawaahazim8782
    @rawaahazim8782 4 роки тому

    what is the Governing Equations of VOF model?

  • @ابوعائشة-ج2م
    @ابوعائشة-ج2م 5 років тому +1

    Can you help me please to simulate bubble column?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  5 років тому

      Did you check out my multiphase simulation project playlist?

  • @markcsete1570
    @markcsete1570 4 роки тому

    Dear József, I just followed every step of your video, and now at opening paraview the "Cell Arrays" are empty. It means, that the before given settings (0, constant etc.) are not used, right? What did I do wrong? - I cannot change the parameters on the top -

    • @markcsete1570
      @markcsete1570 4 роки тому +1

      Ok everybody, please make sure to run the solver properly before asking! I did not run the solver and I paniced.. It is working now properly, making the 3rd denser mesh. Thank you József!

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  4 роки тому +1

      @@markcsete1570 I am glad it works!

  • @aurelianfurcoiu2262
    @aurelianfurcoiu2262 6 років тому

    Jozsef, how do you simmulate a wind tunnel?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому +1

      I have never done it before. I would look for the geometry, mesh it, start with a steady state simulation and if transient effects are needed, use those results as iitial condition for the transient simulations.

    • @aurelianfurcoiu2262
      @aurelianfurcoiu2262 6 років тому

      Yes I would need a multiphase simulation as I want to determine the amount of condensation in the model test area

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому +1

      Wow, that is even more challenging. Start simple by replacing my stl files with yours and progress from there.

  • @divyajyotibasu3001
    @divyajyotibasu3001 3 роки тому

    Hi Jozsef, amazing tutorial! Request you to create one on cavitation in a submerged bluff body in openFOAM. Regards!

  • @SalaiSargunanSParamanantham
    @SalaiSargunanSParamanantham 8 років тому

    thank you very for uploading this video. Can you upload pool boiling model video with three phase because i was struggle with last 3 months plz help

  • @TheSouresh
    @TheSouresh 9 років тому +1

    Hello, I would like to learn more about multi phase simulation in oopenFoam and about heat transfer simulations.Can you please help me.Any type of help will be appreciated.Thank You
    P.S. your tutorials are awesome.I learnt the basics of OpenFoam from your tutorials :)

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому

      Souresh Pal I am not sure how I can help. Watch the tutorials and modify them to your actual case. Otherwise you can google it. CFD Online is also a good starting point.

    • @TheSouresh
      @TheSouresh 9 років тому

      ok Thank You..By the way is it essential that my C++ knowledge should be very good? I know the basics of C.But it was never my strong point.But the CFD codes of openFOAM I understand them very well the ones you have explained in your tutorials.So please Advise...

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  9 років тому +1

      No it's not essential. Only if you want to modify the models

  • @anirban479
    @anirban479 7 років тому

    hello...please sir discuss about bubble column simulation of multiphase modelling useing openFoam in your next video

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  7 років тому

      I will post a video on more tutorials (also on updates of my tutorials) in the next couple of weeks, please stay tuned!

  • @bansishah2091
    @bansishah2091 3 роки тому

    the command "nano blockMeshDict" isn't working for me !

  • @ing.nicola1706
    @ing.nicola1706 5 років тому

    why alpha.water and not alpha.air ? what changes in fvsolution if i call it oil instead of water ?

    • @ing.nicola1706
      @ing.nicola1706 5 років тому

      the answer is exactly in ua-cam.com/video/7w2kdxFAq7k/v-deo.html&list=PLcOe4WUSsMkF93STOampeX-U8hhgbFRbm&index=4 ...

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  5 років тому +1

      You define it in constant/transportProperties. The first entry counts. You can change it though. YOu have to be consistent.

  • @mayankbhuwal810
    @mayankbhuwal810 8 років тому

    Hello Sir :)
    I created the dummy file to open in paraview but unfortunately i am getting error that file cannot be open :(

  • @fitnessmythwalakaka
    @fitnessmythwalakaka 7 років тому

    Hi would it be possible to do this with oil and water? I

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  7 років тому +1

      Sure. Only oil is easy, just change the material properties in transportProperties. However, there is also a solver for multiple fluids in OpenFOAM.

    • @fitnessmythwalakaka
      @fitnessmythwalakaka 7 років тому

      József Nagy Thank you for getting back to me! Have a good day :)

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  7 років тому

      I am glad to have helped!

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому

      If you know the interfacial tension bewteen oil and water you can give it a go, sure.

  • @christiancosenza4091
    @christiancosenza4091 7 років тому

    How can I do the same with comsol ?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  7 років тому +1

      I have no experience with comsol. But maybe give it a try in OpenFOAM. Here is a video, how to install it in Windows 10 :
      ua-cam.com/video/xj0dB_PsElg/v-deo.html

  • @afauzia1993
    @afauzia1993 6 років тому

    dear Jozsef,
    can you teach me about blockMeshDick position x y z in dambreak case?
    My proffesor give me task for change the dimension of dambreak case, and i dont know about dambreak using scale (convert to meters 0,146). can you make that tutorial video in your youtube? hehehehe,
    Thank you very much!

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому +1

      blockMeshDick? :D Which position do you want to change?

    • @afauzia1993
      @afauzia1993 6 років тому

      what i should say.. hahaha, i'm sorry.
      blockMeshdict..
      That's file give our information about dimension of that case. in this case, we get a square result.
      for instance that position in blockMeshDict give :
      vertices
      (0 0 0)
      (1 0 0)
      (1 1 0)
      ....
      and, my proffesor told me to change that position until look rectangular. do you know about that?
      Thank you Jozsef.

    • @afauzia1993
      @afauzia1993 6 років тому

      i want to change dimension in after water coloumn, because, hopefully, i will get rectangular result..

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому

      You mean the obstacle?

    • @OpenFOAMJozsefNagy
      @OpenFOAMJozsefNagy  6 років тому

      Without the obstacle?

  • @DaylightDigital
    @DaylightDigital 9 років тому

    Here is a movie of this simulation at 1/6th real-time speed on the refined mesh.
    damBreak_refined: ua-cam.com/video/a9lFCGLn4Eg/v-deo.html

  • @susieatim128
    @susieatim128 Рік тому

    Pp