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Hi Guys,

I try to simulate a quiet river. But I got the problem that in the areas where the water is not moving at all(or is really really slow), it is moving up and down all the time and looks like little hills. It is not flat what you would expect.I know it is possible to do with other programs but has anybody a solution for houdini ? I tried already the swirl kernel, a sop to settle down the y axis(based on velocity) and a blending with a simple grid based on the velocity. Is there an official way in the simulation process?

I am thankful for any advice

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It is difficult to see what you mean without any further explanation. Can you provide us with an image or a scene file?

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Thanks for your answer. mhh this is a bit complicated.I can just try to explain it better. When you have a simple flat tank and start the simulation you will see after a few frames you will have a motion in the water without any extra forces. And I simply want that without forces the water is flat like a grid. I saw an old post where Jeff Wagner said with the swirly kernel it works better. But still you have the movement from nowhere. I am using version 16.0.717.

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There are many factors that can cause this. As Whatsinaname said, is hard to tell without seeing/knowing more in detail. Just for name a few of them it could be: scale of the river, velocity smoothing, volume/particle resolution, geometry of the river, water forced to go over little hills instead of go around of it and so on.

Swirly kernel should help in this case.

 

The first thing I would check is the velocity smoothing. Maybe try to visualize the velocity/vorticity in the simulation. It could give you a better idea on what's going on.

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Hi. Is there a chance you can upgrade your houdini? The latest houdini is quite stable for flip sims. I think that would help you. I tried with houdini 16.5 and 17. Recreated the same scenario as you. It works!

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oh wow okay. I can use 16.5 to test it. 17 will take a while until we use it. I will test it and let you know and also I will make a test scene at the weekend to show my problem a bit better. Thanks for the feedback

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Hey so I tried it in 16.5 and 17 and still have the same problem. Could you send me your scene to check if it is that what I am looking for. To explain again what I am looking for. When I create a new flip tank and start the animation for 20 frames. I want that after the meshing the water is flat like a grid with no noise at all, but still a high res mesh. I know I can get if I increase the Influence Scale in the mesh process but I lose to much details with this technique.

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8 hours ago, Strooja said:

Hey so I tried it in 16.5 and 17 and still have the same problem. Could you send me your scene to check if it is that what I am looking for. To explain again what I am looking for. When I create a new flip tank and start the animation for 20 frames. I want that after the meshing the water is flat like a grid with no noise at all, but still a high res mesh. I know I can get if I increase the Influence Scale in the mesh process but I lose to much details with this technique.

Oh. That sounds bad. Unfortunately I do not have houdini at home. So I won't be able to share a file. 
  By the way, why don't you just use one frame for the static water?

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