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Old   April 3, 2013, 18:03
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I am modeling 2D airflow passing an aerofoil inside the wind tunnel in the Fluent and Gambit.

The geometry is, the wind tunnel is as a rectangle.

However, when I see the animation, the flow of the wind is like the flowing inside a closed area and trapped.

It flows rotating around inside the rectangle.

What happened?

How to solve it?

Change the type of the boundary?

I also read "reversed flow in outlet"

Thank you
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Old   April 3, 2013, 23:12
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some pics please ...
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Old   April 4, 2013, 00:52
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Quote:
Originally Posted by Far View Post
some pics please ...
This is the picture.

Unfortunately, I can not watch the animation anymore because the display window is becoming blank and black when the iteration process is running.

The problem occurs too when I playback the animation.

Only if I know how to fix the blank-and-black screen problem, I will attached the animation file as a movie instead of a picture.
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File Type: jpg flow over cylinder, laminar, steady.jpg (36.8 KB, 27 views)
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Old   April 4, 2013, 01:14
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specify symmetry condition on side, top and bottom walls.

The model in test section is airfoil or cylinder?
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Old   April 4, 2013, 01:43
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Quote:
Originally Posted by Far View Post
specify symmetry condition on side, top and bottom walls.
Which side I should specify as a symmetry?

Right side, left side, or both?

This is the image of the contour of the vorticity magnitude when I change the boundary conditions of the top edge and the bottom edge from velocity inlet to symmetry and keeping the left edge as a velocity inlet and the right edge as the pressure outlet.

Still have the "reverse flow in the outlet" message.

I still can't upload the movie because of the blank-and-black screen problem.

Quote:
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The model in test section is airfoil or cylinder?
Actually it's a cylinder.
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File Type: jpg new boundary conditions.jpg (35.7 KB, 7 views)
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Old   April 4, 2013, 01:47
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Both sides and also top and bottom wall be specified as symmetry.
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Old   April 4, 2013, 01:59
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This is the display of the contour of the velocity magnitude when the boundary conditions of the all edges of the rectangle were changed to the symmetry.
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File Type: jpg all edges of the rectangle are symmetry.jpg (27.3 KB, 14 views)
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Old   April 4, 2013, 02:09
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All BC changed to Sym I hope you are not talking about inlet and outlet.

The results in contour plot are from fully converged solution? If not run it for longer duration.
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Old   April 4, 2013, 02:37
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Quote:
Originally Posted by Far View Post
All BC changed to Sym I hope you are not talking about inlet and outlet.
Yes. All BCs were changed to sym.

The original BCs before they were changed are:

left edge: velocity inlet
right edge: pressure outlet
top edge: velocity inlet
bottom edge: velocity inlet

I compute it from the left edge to the right edge.

The wind is flowing from the left side to the right side.

The left edge should be as the inlet and the right side as the outlet.

Quote:
Originally Posted by Far View Post
The results in contour plot are from fully converged solution? If not run it for longer duration.
No.

The contour is displayed before the iteration process.

As I was already told you, I have a problem and the problem is the display become blank-and-black when the iteration is processing.

This is the reason why I can't upload picture or animation after fully converged.
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Old   April 4, 2013, 02:43
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From left to right flow this should be the BC:

left edge: velocity inlet
right edge: pressure outlet
top edge: symmetry
bottom: symmetry

Quote:
Originally Posted by spincfd View Post
As I was already told you, I have a problem and the problem is the blank-and-black display.
Are you saving frames to do an animation? Are they still blank?
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Old   April 4, 2013, 02:49
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Quote:
Originally Posted by Bollonga View Post
Are you saving frames to do an animation
No but once it works.

However, now isn't working anymore.

Quote:
Originally Posted by Bollonga View Post
Are they still blank?
Yes.
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Old   April 4, 2013, 02:56
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The display window of the animation is blank-and-black too when I playback the animation after fully converged.
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Old   April 4, 2013, 03:11
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Are you running a steady or a transient case?

Are you following the steps at calculation activities/solution animation tab and selecting the contour you want with the frequence you want?

I think you should get the simulation right first, and once it's okay set an animation in the calculation activities/solution animation tab.
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Old   April 4, 2013, 03:32
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Quote:
Originally Posted by Bollonga View Post
Are you running a steady or a transient case?
Well, I check the steady option under define > models > solver.

Quote:
Originally Posted by Bollonga View Post
Are you following the steps at calculation activities/solution animation tab and selecting the contour you want with the frequence you want?
I think you should see one of the image I already uploaded in this thread.

Clear it says Fluent 6.2.16.

Calculation activities is available in ANSYS 12, am I right?

Quote:
Originally Posted by Bollonga View Post
I think you should get the simulation right first, and once it's okay set an animation in the calculation activities/solution animation tab.
I think you should read the entire posts inside this thread before posting your message.

It's clearly written:

"I can not make the animation/simulation because the display window is become blank and black (or I would just say become blank without black because the background color can be changed from black to white), nothing is displayed in this display window, when the iteration is start processing."
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File Type: jpg blank display.jpg (17.2 KB, 4 views)
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Old   April 4, 2013, 03:47
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Quote:
Originally Posted by spincfd View Post
I think you should read the entire posts inside this thread before posting your message.
I've read your post completely before posting. But I don't know how you are defining your animation step by step.
When I do a simulation, normaly a time-dependent case, I wait until the case is converged and then I record the animation.
I was suggesting you put BC right, let the case run, and then set the animation.

Quote:
Originally Posted by spincfd View Post
Well, I check the steady option under define > models > solver.
From this I guess you want a convergence animation rather than a time animation, right?
Quote:
Originally Posted by spincfd View Post
I think you should see of the image I already uploaded.

Clear it says Fluent 6.2.16.

Calculation activities is available in ANSYS 12, am I right?
I'm not sure about that, but in Fluent 6.2 there should be an option Solve/animate/define or something similar to select the frames and frequency.

Remember I'm just trying to help you. Good luck.
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Old   April 4, 2013, 03:58
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Quote:
Originally Posted by Bollonga View Post
From this I guess you want a convergence animation rather than a time animation, right?
Well, any of them is fine.

Quote:
Originally Posted by Bollonga View Post
I'm not sure about that, but in Fluent 6.2 there should be an option Solve/animate/define or something similar to select the frames and frequency.
Yes.

I set the animation in the Solution Animation window (Solve > Animate > Define).

But I am not sure of the frames and frequency you're talking about.

Maybe in the Solve > Animate > Playback.

Frames is the start frame, increment, and end frame.

Frequency is the replay speed such as within the slow to fast range.

Is it correct?
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Old   April 4, 2013, 04:30
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Quote:
Originally Posted by spincfd View Post
Well, any of them is fine.
If you want to the see the flow time evolution it must be a transient case.
If you want to animate how aproximate solutions are getting to the converged one, it should be a steady case.

First, in a menu like the one in picture 1 you should select how often you want to save a frames, every X iterations or timesteps (in the transient case). In define you go to menu in picture 2. You select what exactly want to be recorded. Specify a name and a folder and save.

Then the simulation is run and you'll get a frame recorded in the specified folder every X iterations/timesteps. Do you have this files in your case?

Once it's finished you can play it in the menu like the one in picture 3.

I don't know if you have followed all this setps and the problems persists.

In fluent users guide (ansys 12) all this is explained in 26.16 Animating the solution.

You may find some usefull tutorials here:
https://confluence.cornell.edu/displ...arning+Modules
Attached Images
File Type: png 2013-04-04_1012.png (18.0 KB, 7 views)
File Type: png 2013-04-04_1012_001.png (18.6 KB, 6 views)
File Type: png 2013-04-04_1013.png (19.3 KB, 5 views)
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Old   April 4, 2013, 08:02
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Quote:
Originally Posted by Bollonga View Post
If you want to the see the flow time evolution it must be a transient case.
If you want to animate how aproximate solutions are getting to the converged one, it should be a steady case.

First, in a menu like the one in picture 1 you should select how often you want to save a frames, every X iterations or timesteps (in the transient case). In define you go to menu in picture 2. You select what exactly want to be recorded. Specify a name and a folder and save.

Then the simulation is run and you'll get a frame recorded in the specified folder every X iterations/timesteps. Do you have this files in your case?

Once it's finished you can play it in the menu like the one in picture 3.

I don't know if you have followed all this setps and the problems persists.

In fluent users guide (ansys 12) all this is explained in 26.16 Animating the solution.

You may find some usefull tutorials here:
https://confluence.cornell.edu/displ...arning+Modules
I know there are two options in the When drop-down menu, time step and iteration, in the Solution Animation window.

But why there is only available iterate option under the Iterate window, and it's different as the second image.
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File Type: png iterate window, no time step option.PNG (7.6 KB, 6 views)
File Type: png iterate window, time step option.PNG (12.6 KB, 5 views)
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Old   April 4, 2013, 08:45
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Quote:
Originally Posted by spincfd View Post
But why there is only available iterate option under the Iterate window, and it's different as the second image.
These pictures are from the run calculation menu?

The first one looks like the steady simulation iterations panel, no timesteps in a steady simulation.
The sencond one is to set up the transient simulation iterations. You can choose how many iterations per timestep, how many timesteps and the size of the timesteps.

This is to set the iterations of the solver, nothing to do with animation.
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Old   April 4, 2013, 10:14
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