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April 3, 2013, 18:03 |
Wrong Result?
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#1 |
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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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April 4, 2013, 00:52 |
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#3 |
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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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April 4, 2013, 01:43 |
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#5 |
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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. Actually it's a cylinder. |
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April 4, 2013, 01:59 |
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#7 |
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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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April 4, 2013, 02:37 |
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#9 | ||
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Quote:
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:
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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April 4, 2013, 02:43 |
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#10 |
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Francisco
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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 Are you saving frames to do an animation? Are they still blank? |
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April 4, 2013, 02:49 |
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#11 |
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April 4, 2013, 02:56 |
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#12 |
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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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April 4, 2013, 03:11 |
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#13 |
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Francisco
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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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April 4, 2013, 03:32 |
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#14 | ||
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Well, I check the steady option under define > models > solver.
Quote:
Clear it says Fluent 6.2.16. Calculation activities is available in ANSYS 12, am I right? Quote:
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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April 4, 2013, 03:47 |
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#15 | ||
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Francisco
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Quote:
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. From this I guess you want a convergence animation rather than a time animation, right? Quote:
Remember I'm just trying to help you. Good luck. |
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April 4, 2013, 03:58 |
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#16 | ||
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Quote:
Quote:
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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April 4, 2013, 04:30 |
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#17 |
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Francisco
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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 |
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April 4, 2013, 08:02 |
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#18 | |
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Quote:
But why there is only available iterate option under the Iterate window, and it's different as the second image. |
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April 4, 2013, 08:45 |
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#19 | |
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Francisco
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Quote:
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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