Is there anyway to simulate the open channel flow without using the multiphase model??

- October 15, 2018 at 4:13 pm
  
  Rana Nasser
  Subscriber
  
  Hi everyone!
  
  My model is a regulator (water structure constructed on a canal ( open channel)) - the structure is shown in the attached image - subjected to a a seismic excitation (inputted as acceleration time history using an APDL command), so I'm using transient analysis. To take the effect of the water motion due to the seismic excitation on the structural elements of the regulator, I'm trying to use system coupling with a fluent analysis which is used to simulate the water flow in the canal.
  
  Is there anyway to do this without using the multiphase model in fluent for simulating the water flow in the canal? or can one use one phase only with free surface boundary condition ( I don't want to model the air domain because the structure is too big and the model is taking a long time to run the analysis and I'm a biggener in ansys fluent too)
  
  The flow in the canal is a subcritical and the water velocity is low and there is no large waves, so I'm only interested in the effect of response of the water on the regulator's elements due to the earthquake. ( I'm doing this simulation to make a stresses analysis to the structural elements after the earthquake exitation).
- October 16, 2018 at 5:53 am
  
  Keyur Kanade
  Ansys Employee
  
  Hello,
  
  You will have to use multiphase model for this as water and air will be involved.
  
  If you dont want to use multiphase model then please reduce your problem so that you have only water in the fluid domain and no air. Then you can go ahead with single phase.
  
  Regards,
  
  Keyur
  
  FSI help
  
  https://www.youtube.com/watch?v=9aHWSZghFn8&t=5s
- October 16, 2018 at 6:57 am
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  Exactly what kknade suggested: You can handle it with a single phase flow and assume a free slip boundary /symmetry boundary at the free surface. This would however smooth out the turbulence effects and does not account the motion of the free surface but the approach is mostly used.
- October 18, 2018 at 12:34 pm
  
  Rana Nasser
  Subscriber
  
  I've tried to use the suggested approach on a simple wall model to test the steps and the errors which I may face in my model, so I tried to do the same steps of the tutorial in the Keyur comment with changing the boundary conditions of some faces ( wall side 1 become inlet, wall side become outlet, wall top become symmetry 3) then I have run the model and I faced this error:
  
  *** FATAL ***                           CP =       0.312   TIME= 14:43:14
  MAPDL is unable to connect to the system coupling service on
  vortex.data.microsoft.com through port 50319. Please check ANSYS
  execution options -schost and -scport for a System Coupling analysis
  and ensure that the host name and the port number are correct.
  
  *** FATAL ***
  Random read error on unit=     16 possible corrupt or missing file.
  I/O status error=      0
  
  ************************************************************************
  The above error is non-recoverable by ANSYS
  ANSYS run terminated by the indicated error
  
  *** FATAL ***                           CP =       0.312   TIME= 14:43:14
  MAPDL is unable to connect to the system coupling service on
  vortex.data.microsoft.com through port 50319. Please check ANSYS
  execution options -schost and -scport for a System Coupling analysis
  and ensure that the host name and the port number are correct.
  
  *** FATAL ***
  Random read error on unit=     16 possible corrupt or missing file.
  I/O status error=      0
  
  ************************************************************************
  The above error is non-recoverable by ANSYS
  ANSYS run terminated by the indicated error
  
  ************************************************************************
  
  How can I fix this?
  
  The archive file of the project is attached below, Thanks so much!!
- October 18, 2018 at 12:56 pm
  
  Karthik Remella
  Administrator
  
  Hello,
  
  It looks to me like the crash occurred with the mechanical tool. Does this happen at the beginning of your mechanical simulation? Or in the middle as the simulation is running?
  
  You might want to start a new thread under 'Structural Mechanics' and post this question. Please reference this current thread in the new question you are going to create. Please post as many screenshots as possible and provide the necessary details. As ANSYS employees, we will not be able to download any attachments. We answer questions using the information you provide in your post.
  
  I hope this helps.
  
  Thank you.
  
  Best Regards,
  
  Karthik
- October 18, 2018 at 12:57 pm
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  Does it mean that your questions were related to structural?
- October 19, 2018 at 1:00 pm
  
  Rana Nasser
  Subscriber
  
  I'm not sure is it a structural or license issue!
  
  I found this conversation while I was searching for a method to handle this error:
  
  where they are saying that this error is because of the licence shearing!!
  
  https://www.cfd-online.com/Forums/fluent/134554-fsi-problem-system-coupling-fail-couple-fluent.html
- October 19, 2018 at 1:08 pm
  
  Keyur Kanade
  Ansys Employee
  
  Can you please first test if you can run fluids and mech simulations independently.
  
  Also please check if you have everything on same machine.
  
  Please check Systesm Coupling Uers Guide.
  
  Regards,
  
  Keyur
- October 19, 2018 at 1:56 pm
  
  Karthik Remella
  Administrator
  
  Hello
  Just to add to Keyur’s comment above, could you please try and running a simple test case to Debug the issue you might be having?
  
  Also one small note - we, as Ansys employees, will not be able to comment on discussions occurring in public forums such as CFD-online. This is just a FYI.
  
  Please let us know your findings.
  
  Thank you.
  
  Best Karthik