Rain Drop - Water splash

Discussion about fluid simulation in Realflow 4
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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Mon Dec 07, 2009 6:05 pm

Hello everyone,
I'm trying to create a realistic, water drop, splash.
Like this pic:

I'm creating nature "moments", shapes of fire and water. I'm using Maya and Rf and I'm cheeking a bit of FumeFx.
This is not for commercial use but for my Master Thesis in Computer Animation.
Here you will find some tests I've created so far:
http://www.vimeo.com/vitorteixeira
Hope someone can give me a tip. It would meant something.
Thanks for your time.
These are the images of my last test:




Just Zoom in to see the values.
Cheers


lukeiamyourfather
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Rain Drop - Water splash

Postby lukeiamyourfather » Mon Dec 07, 2009 9:27 pm

Thin forms like the rim of the splash in the reference image will require many particles (much higher emitter resolution) to resolve the details. Also crown splashes are especially difficult to get in RealFlow by just dropping one fluid into another, it might require some scripting or daemon trickery to get exactly what you're looking for. Cheers!

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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Tue Dec 08, 2009 6:21 am

Really.
Well I´m not, yet, into scripting.
And if I give an extra gravity parameter into the drop?
or change the viscosity and the internal pressure of the still water?
I just have to make the splash go up.
I wasn't expecting to go by scripting. Do you have any idea what type of scripting?
Thanks

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bitSeq
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Rain Drop - Water splash

Postby bitSeq » Tue Dec 08, 2009 3:03 pm

Hi Vitor.

I have found that it helps to have a plane just below the surface of the water which will give the splash more reflected force.

You could also experiment with exclusive gravity for the drop and surface water, perhaps a little less gravity for the surface might help.

Cheers

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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Tue Dec 08, 2009 3:05 pm

So I create a fill object emitter within a cube.
And at half of that I put an plane? Right?

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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Tue Dec 08, 2009 4:21 pm

http://fusioncis.com/research/splashes/
Here we a find a very good example.
Does someone knows how they have created that?

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starlighter
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Rain Drop - Water splash

Postby starlighter » Tue Dec 08, 2009 5:54 pm

bitSeq wrote: Hi Vitor.

I have found that it helps to have a plane just below the surface of the water which will give the splash more reflected force.

You could also experiment with exclusive gravity for the drop and surface water, perhaps a little less gravity for the surface might help.

Cheers

Exactly!!
Listen to what bitSeq said, that's a great tip which i discovered in my last project, some month ago! I intend to make a bit of a study on that matter, since it's a pretty common problem.

Fluid needs to have something that will push some of it upward, and since there is nothing except itself, it has to have some fake object that will reflect the force up!

I'm about to make some experiments on layering two fluid on top of eachother with different parameters, since that's probably more physicaly accurate way of behaving the fluid, but i'm not sure will it mix up...

But meanwhile, whenever i need to get a a nice splash, i just fill the container with a thin volume of fluid, and get as much particles as i can...(2 millions if possible...)
I'm filling the container because that way you can introduce more particles into the simulation...

So to sum up, fill the container, with a thin volume of fluid...really thin..(when settled of course), and then you can either drop a drop of fluid, or you can fell free to add some .sd animation of a sphere falling in. Then, gradually add some deamons, experiment with them, with fluid parameters...and you'll get (almost) what you want!
This way, the bottom of a container will behave like a plane, and it'll reflect the force of particles upward.

One tip for settling the fluid in a container! When you figure out what height of fluid initially you need, for it to settle in a desired volume after it calms down, type in the resolution to be the x2 then the one you plan to use. And then, in the first frame, before you let them to settle down, just cut the resolution by 2, and let the simulation of settling the fluid begin.
This way, it will make the settled fluid much more natural, and particles won't line up on top of eachother forming thin columns, but rather they'll assume a little more chaotic state.

I'll post one thread in few days, sharing what i've learned during the past month.
Keep walking!
web: www.startlightvfx.com
vimeo: http://www.vimeo.com/13276781

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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Tue Dec 08, 2009 6:29 pm

Thats great.
Thanks a lot.
Don't you think that if we fill a container with, for example a square emitter, and change the values of V & H random we will have that effect on the still water?

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starlighter
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Rain Drop - Water splash

Postby starlighter » Wed Dec 09, 2009 8:19 am

Yes, you are right 'bout that, but i was refering to a method when using a FillObject emiter. It's better to use basic emiter, and leave it to fill the object, only it takes a bit more of time, but the position of particles will be better.
Keep walking!
web: www.startlightvfx.com
vimeo: http://www.vimeo.com/13276781

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Vitor Teixeira
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Rain Drop - Water splash

Postby Vitor Teixeira » Wed Dec 09, 2009 3:45 pm

Ok.
I'll test both ways then.
Thanks


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