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How can I make FLUENT solve 1D problem

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Old   April 11, 2007, 10:51
Default Re: How can I make FLUENT solve 1D problem
  #21
bashu
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Dear Nime,

I posted my previous respond before replying to your part. I agree with you that a two phase flow can not be modeled in 1D unless the densities are so close to each other or the gravity (or other body forces) does not have any effect on the flow for various reasons. The radial segragation is the main reason these flows are difficult CFD cases and so if the effect of 2nd dimension is ignored I am not sure what is left. Now as you may know people are discussing whether the KTGF is the cause or effect of the radial segragation in vertical flows.

All said I still think if Saleem wants to try a 1D case he should go ahead and do it. The results should be studied very carefully since it may be too simplistic.

I ran a 1D fluent model but the flow was superimposed and all I cared about the model was to compare the kinetics that I had used in the UDF and verify the correctness of the equations with a 1D kinetic model.
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Old   April 13, 2007, 09:48
Default Re: How can I make FLUENT solve 1D problem
  #22
Danny
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Dear all,

In my test of 1D two-phase simulation, I found the solid mass fluxes of the inlet and outlet are not same under steady-state condition although the convergence criteria is satisfied. Now my questions are:

(1)what could be the possible reason for this problem? and what action should be taken for dealing with this?

(2)In addition, what kind of monitoring varibles are suited to judge whether the final results are convergent or not? In my simulation I used the area-integral gas/solid mass flux at different axial sampling section-area. Do you have other recommendation?

Please give your ideas.

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Old   April 16, 2007, 08:20
Default Re: How can I make FLUENT solve 1D problem
  #23
bashu
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Another example of 2-phase 1D run. Could you tell us more about phase properties?

In many two-phase cases the flow behavior is of oscillatory nature as the gravity and drag are acting against each other. There are other cases that you can reach a steady solution.

Check the mass balance over a period of time (3-5 times the period) and once the time average mass balance is zero, you have a quasi steady solution.

How does the mass flux that you are monitoring look like with time?
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Old   April 16, 2007, 15:17
Default Re: How can I make FLUENT solve 1D problem
  #24
Danny
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The gas-solid CFB sytem is air & FCC_particle. Their densities are 1.225 kg/m3 and 1700 kg/m3,respectively.

I do not try the time-averaged solution because it takes long time. So, I attacked directly for the steady-state solution. The monitored mass fluxes become level-off after a number of iterations. Ny the way,the viscous model in my simulation is laminar flow. The intial field is zero for all variables. That is all the details.

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Old   April 17, 2007, 08:20
Default Re: How can I make FLUENT solve 1D problem
  #25
bashu
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Unfortunately I don't have any explanation for the difference of mass flow rates in outlet and inlet if the monitor mass flux at different elevations are level and their values are equal and what you expect to get.

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Old   April 30, 2007, 09:43
Default sloshing
  #26
sudhir
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hey im doing sloshing project.anyone know abt sloshing. i need some guidelines
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Old   May 2, 2007, 07:52
Default Re: sloshing
  #27
Phil
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what do you mean?

If the liquid is sloshing in a tank that also contains air or any other gas then it is a free surface flow and you need to use the multi-phase tools.

As you want to see how the fluid changes with time you need the unsteady solver.

Phil
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Old   May 3, 2007, 03:24
Default Re: sloshing
  #28
sudhir
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hi, we can use FLUENT for sloshing.im working in it.do you know more abt sloshing. i just started my work.sudhir86@gmail.com is my id. plz contact me in that id.
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Old   May 3, 2007, 04:15
Default Re: sloshing
  #29
Phil
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i haven't worked directly on this but have you done all the multi-phase tutorials?
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Old   May 4, 2007, 02:48
Default Re: sloshing
  #30
sudhir
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no. just learning basics in FLUENT.
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Old   May 4, 2007, 09:00
Default Re: sloshing
  #31
Phil
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doing the multiphase or VOF (I think) tutorials wouldn't take long and would give you these guidelines. Look into these methods in the user guide and see which is best suited.

WHY DON'T PEOPLE JUST DO THE TUTORIALS OR REFER TO THE USER GUIDE INSTEAD OF SAYING "DO MY WORK AND GIVE ME THE ANSWER ASAP! NO PLEASE OR THANKS".
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Old   May 6, 2007, 07:49
Default Re: sloshing
  #32
Phil
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One of my colleagues does free surface flows for his PhD so I would be best to forward your question to him. I'll get him to post a response on this thread in the next few days.

Phil
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Old   January 17, 2014, 07:04
Default Problem with 1D problem
  #33
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Hi everyone!!!

I am trying to simulate a 1d heat transfer in a medium confined between two large walls (top and bottom wall). I created a 2d rectangle in icem cfd. For top and bottom lines I have given the boundary conditions as walls. But I am not clear what boundary condition I should use for left and right lines which are not supposed to be present. (I created them only for meshing)..


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