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Andy_Ireland

Lumpy/blobby surface around collisions with splash tank

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I have a splash tank set up with some collision geo and the water around the collision geo has a blobby/lumpy look to it, see video here:

https://vimeo.com/189853378/db0edca909

Splashtank has a Particle separation of .015 and particle radius scale of 1.2
Flipsolver has 2 max substeps and collision supersampling enabled with 2 sample per axis
Splashtank sim has 2 substeps

The collision geo looks accurate to me enabling the collision guide and viewing as wireframe

Do any of the smart people on here know what might cause this kind of "blobbyness".
Will be doing some kind of wedge tests to try and figure it out but any pointers would be very welcomed
 

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Hi Andrew, yep, it's kind of strange behavior. Without the hip file I feel like the problem is the collider, but it's hard to tell.... Have you "polycapped" the geo?

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Also, I feel like the res of the flip it's kind of low. How many particles do you have? I see the parts separation is 0.015 but we don't know how big is that geo. I think in that particular shot you can use a relative small flip tank, surely not so deep as there's almost no action, and go with smaller parts separation. It's well optimized the size of the tank? A thin layer of water should do the job I suppose.

Cheers!

Marco

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Thanks for your reply Merlino, the collision geo was a mesh from Photoscan that I remeshed in ZBrush,
I used some kind of polycap function in zbrush (it was quite a while ago and I cant recall the functions name)
its a statue so quite a complicated bit of geometry so posting the complete file is difficult?
You can see the main collision geo settings here and a wireframe view of it with collision guide enabled.

I will try polycapping it for sure

Capture.PNG

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20 minutes ago, merlino said:

Also, I feel like the res of the flip it's kind of low. How many particles do you have? I see the parts separation is 0.015 but we don't know how big is that geo. I think in that particular shot you can use a relative small flip tank, surely not so deep as there's almost no action, and go with smaller parts separation. It's well optimized the size of the tank? A thin layer of water should do the job I suppose.

Cheers!

Marco

This is a good point, I was looking at doing this just last night but couldnt figure out how to, where can I make the depth of the particles thinner?

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You can resize the tank itself in the Flip solver settings, "Volume limits". Depending on how you created the sim it can be referenced to another node or not. In any case you can cut the reference, if you want, and modify it there. 

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I had resized the tank, I was wondering if there was a way to change the default depth of the particles that fill it.
At work at the moment so don't have the file but will test out everything you have mentioned

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Another option, but really I don't know if it's necessary (I think is not), is to use the wave layer tank. That way you have a layer of particles and you can adjust how deep is it, but I think it's useful when you actually have waves, in your case (calm water) you can simply resize the tank in -Y, that way you are controlling the deepness.

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Thanks Merlino, I tried it out before and might take another look, this is a just a little personal project I've been at for a while now.
Appreciate your help

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You should check out John Lynch's excellent Houdini 15 FLIP fluid enhancements video. And download the sample file for reference. Lots of learning. I feel the 2 most important things when using the FLIP tank shelf tool is establishing your scale FLIP tank size and Particle Separation

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Thanks Astmis, I have watched it a few time, I have managed to get my sim to look a lot better and it is currently rendering,
a smaller particle separation was the main thing that helped

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