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-   -   Wave Generator/Wave level Problem (https://www.cfd-online.com/Forums/star-ccm/173554-wave-generator-wave-level-problem.html)

MySoccer June 22, 2016 07:15

Wave Generator/Wave level Problem
 
2 Attachment(s)
Hello Guys,

i study Bachelor of Engineering in the 6. Semester and i have a problem with my CFD Project. I hope someone can help me.

I have to simulate an Wave Generator. See the Pictures i have uploaded.

My first question is how to fix a point on a isosurface? The isosurface is the border between air and water.

Currently i have a little Ball wich is swimming on the water. The Z Posiotion is visualiezed in a report/plot.

The first problem is that the Ball canīt show the exact high of the wave because it has a mass inertia.

The next Problem you can see on the second picture. Seems like the water level increases steadily. This isnīt possible. I have no Inlet in my simulation. I donīt know how the water level can increase!

The waves are generated by Morphing the left wall. Look at the Video.
https://www.dropbox.com/s/n8g2lh4ww0...55_40.avi?dl=0

The thing at the right site of the pool is to damp the waves. I dont want to have a reflection from the right wall of the pool.

marmot June 24, 2016 03:18

Nice problem the only advice I can give is to create a field function
$Volume*$VolumeFractionWater*$DensityWater

Create a sum report and monitor this field function it should remain constant like you said, if not perhaps you are not converging each time step enough

MySoccer June 27, 2016 04:21

Quote:

Originally Posted by marmot (Post 606383)
Nice problem the only advice I can give is to create a field function
$Volume*$VolumeFractionWater*$DensityWater

Create a sum report and monitor this field function it should remain constant like you said, if not perhaps you are not converging each time step enough

Thanks for your help.
You mean that i should create one Field Function with this Definition?

Iīve done this so far and i start it now simulating. Showing the result in a few hours.

MySoccer June 27, 2016 04:46

1 Attachment(s)
Its not constant :(

My Time Step is 0,01s with 5 inner Iterations.

The Amplitude is 20mm and the rotations speed is 60/min -> Omega 6,283

marmot June 27, 2016 05:25

OK I would try cutting the time step in half, leave the 5 inner iterations and see if it cuts in half or just changes how your mass is changing.

silly question I know, but just double check the system is close

If it is a closed system it might be important where you fix the pressure or increase the top of your domain and put a pressure boundary there

MySoccer June 27, 2016 05:29

1 Attachment(s)
Quote:

Originally Posted by marmot (Post 606711)
OK I would try cutting the time step in half, leave the 5 inner iterations and see if it cuts in half or just changes how your mass is changing.

silly question I know, but just double check the system is close

If it is a closed system it might be important where you fix the pressure or increase the top of your domain and put a pressure boundary there

Time-Step 0,005s and the result is the same :/

The System is close. Now i try it out with a pressure outlet at the top of the Pool.

MySoccer June 27, 2016 06:57

No Changes with an Pressure Outlet at the top of the pool.

Anyone has another idea to fix this problem?


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