CFD Online Discussion Forums - Fluent VOF Volume of Fluid Realistic Solution Problem

Hello all, this is my first post, I hope anybody can help me here.

I want to model a full fuel tank and the fuel movement in a wing, but before that I wanted to learn the aspects of VOF and real-time animation of it.

I have constructed a simple tank model. In it, I have put the water volume in an oblique angle in the bottom part of the tank. Then I have defined the gravity which is -9.8 m/s2 in Z direction. From start, with gravity, the water should move in the tank and settle down a little bit.

Using VOF model and with time-step 0.05 secs, I had 1200 iterations and 1200 .dat files to construct the animation. Since time-step is 0.05 secs, 1200 iterations make 60 secs with 20 solutions (frames) per second.

Then I used TecPlot to construct the animation movie, telling it that "you should use 20 solutions (.dat files) to construct 1 second of animation" With these settings I had 60 sec animation movie. But it does not seem realistic. The flow is so sluggish like it is not water, like it is a lot more thicker fluid. When I speed up the movie like 60 frames per second, it is more realistic. But then the reason why I make this animation comes to my mind. I should determine the exact points in animation that can be trouble for the design. I could not trust the computation of Fluent.

Do you have any similar experience or suggestions regarding this?

Please correct me if I am wrong:

since time-step is 0.05 sec, 20 steps make 1 sec.
I should use 20 frames (.dat files) to construct 1 sec of animation.
1200 steps (.dat files) make 1200 frames and from 20 frames per second I should have a realistic 60 secs movie, which I did not.

Regards