Fluids

Fluids

Fluent error

    • snr1
      Subscriber

      I am modelling the absorption process by using the Eulerian multiphase model with species transport model along wth energy equation. For mass transfer, i.e. interaction between the phases, species mass transfer model has chosen. Timestep value = 1e-6 has chosen then initialization was done and after that simulation was run and it immediately results in the following error:


       


      Divergence detected in AMG solver: vof-1


      Divergence detected in AMG solver: pressure correction


      Divergence detected in AMG solver: solution-species-0


      Divergence detected in AMG solver: apour-species-0


      Divergence detected in AMG solver: vof-1


      Divergence detected in AMG solver: pressure correction


      Divergence detected in AMG solver: solution-species-0


      Divergence detected in AMG solver: apour-species-0


      Divergence detected in AMG solver: vof-1


      Divergence detected in AMG solver: pressure correction


      Divergence detected in AMG solver: solution-species-0


      Divergence detected in AMG solver: apour-species-0


      Divergence detected in AMG solver: vof-1


      Error at host: floating point exception


       


      Error at Node 0: floating point exception


       


      Error at Node 1: floating point exception


       


      Error at Node 2: floating point exception


       


      Error at Node 3: floating point exception


       


      Error: floating point exception


      Error Object: #f


       


      Calculation complete.


       


       


      How to solve this error.


       


      Thanking you


       

    • snr1
      Subscriber

       

    • snr1
      Subscriber

    • snr1
      Subscriber

    • DrAmine
      Ansys Employee

      Can you please add more details about the case: mesh, quality, models, boundary conditions and release version.

    • snr1
      Subscriber

      The geometry is as follows:


      There is a pipe and at the bottom of pipe nozzle is there. Through nozzle gaseous mixture will flow and through the annulus solution mixture will flow. The meshed domain is as shown in below:



       


      Quality:



       


      models:


      1. Multiphase-Eulerian model


      2. Energy


      3. SST k-w turbulence model


      4. Species transport model with species mass transfer in phase interactions.


       


      Boundary conditins:



      1. Nozzle inlet: Mass flow inlet


      2. Solution inlet (Annulus) : Mass flow inlet


      3. Nozzle wall : Adiabatic


      4. Pipe wall : Heat flux (negative)


      5 Outlet : Pressure outlet


       


      Fluent version : 18.1

    • DrAmine
      Ansys Employee

      Try to avoid huge cell volume change at the end of the small pipe nozzle. Please use one of the last releases and try again. We ameliorated several things which you are using now.

    • snr1
      Subscriber

      How i can avoid the huge cell volume change at the end of small pipe sir?


      Can i know which things were amelorated in the latest version? and from which version onwards these are implemented?

    • DrAmine
      Ansys Employee

      Use the latest possible versions. Mass transfer and stability have been enhanced.


      For volume cell change, mark cells with cell volume change larger than 2..5: you need to get ride of them.

    • snr1
      Subscriber

      Thank you sir for you reply. But, i dont know how to mark the cells with cell volume change larger than 2.5? can you please elobrate it how to do this.


       And i am using latest version of 18.1 only sir.


      Thanks

    • DrAmine
      Ansys Employee

      Using Adaption Registers.


      Latest version is 2019R2. After 18.1, we have had 18.2, 19.0, 19.2, 19.2 and 2019R2.

    • snr1
      Subscriber

      Dear sir, after adaption of grid also, still the same error is coming.


      How reslove this issue

    • DrAmine
      Ansys Employee

      I have not said do adaption: I said check the region where the cell volume change is large and remesh accordingly. I also said update to the latest possible release. If then still having issues we can discuss further steps.


       


      What you can do is at first to disable mass transfer and check if it is running through.

    • snr1
      Subscriber

      Currently, my institute doesnt have the recent release fluent version license.


      I have done the remesh where the volume has exceeded the 2.5 by using adapt volume.


      With out mass transfer the case is working fine.

    • DrAmine
      Ansys Employee

      And the mass transfer is via? Please screenshots of all interaction panels.

    • snr1
      Subscriber








    • DrAmine
      Ansys Employee
      Henry's law us for modelling adsorption or dissolution of gas in a ideal solution. Try changing from to phase and use latest release.
    • snr1
      Subscriber

      1. Dear sir, according to the theory guide henry law is used for the non-ideal solutions. Here, my application is absorption of gas bubbles in the liquid solution which non-ideal.


      2. I didn't get what do you mean changing from to phase?


      3. Regarding the latest release, my institute currently having 18.1 only.


      4. Will it be possible to model the gas absorption in a liquid solution by using Fluent? If so, which version will be helpful and which models?

    • DrAmine
      Ansys Employee

      1/Check the graph of Henry and Raoult and you will see that is not good for non-ideal solution only when the component mass fraction is small: dilute conditions


      2/You change the phase order in the species mass transfer panel


      3/okay. not good


      4/Yes either with Henry's law or via UDF

    • snr1
      Subscriber

       1. Means in dilute conditions, for non-ideal solutions, Henry's law won't applicable?


      2. In my case, the vapour phase is having a higher mass fraction (0.99), and a solution is having a mass fraction of 0.2 so that the mass will transfer from vapour to solution-phase by species mass transfer.


      3. With henry's law, we have to specify the reference henry constat and temperature dependence, which I don't for my present working pair?. how to calculate that?

    • DrAmine
      Ansys Employee

      1/In dilute conditions Henry law is applicable. 


      2/You need to apply the mass transfer always from liquid to gas: you need just to inverse the order.


      3/That your input: make a literature survey.

    • snr1
      Subscriber

      Dear sir, but in my case, the condensation process is happening. Still, I have to give my transfer from phase as a liquid? But in the actual condensation process, from phase is vapour, so I have given like that. Kindly clarify the doubt.

    • DrAmine
      Ansys Employee

      It does not matter if dissolution or adsoprtion: The mass transfer has to be set so that on left side you liquid and the right side gas.

    • snr1
      Subscriber

      Dear sir, in species mass transfer modelling, whether we have to specify the same species or different species in from and to species?. i.e. whether we have to give from species as water liquid in one phase and to species also as water liquid in another phase or water liquid in one phase and to species as water vapour in another phase?

    • DrAmine
      Ansys Employee

      In the phase interaction panel under Mass. 


       

    • snr1
      Subscriber

      Thats fine sir. But, what my doubt is that,  whether we have to specify the same species or different species in from and to species?. i.e. whether we have to give from species as water liquid in one phase and to species also as water liquid in another phase or water liquid in one phase and to species as water vapour in another phase?

    • Rob
      Ansys Employee

      Depends whether you're transferring between two liquids or liquid to gas? 

    • snr1
      Subscriber

      I am transferring species from gaseous phase to liquid phase, i.e. condensation. My doubt is that, whether I need to specify the same species for species mass transfer or not?

Viewing 27 reply threads
  • You must be logged in to reply to this topic.