Oil splatter on a small scale

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Paul Szopa
Posts: 2
Joined: Thu May 10, 2018 8:47 pm

Oil splatter on a small scale

Post by Paul Szopa » Thu May 10, 2018 9:04 pm

Hi All,
I've just downloaded the demo of RF and am exploring if I can recreate the oil drips on a shirt (shown in attachments) to showcase an oil repellent treatment. I'll be doing it in slow-mo to show things better.

I have a couple of questions:
- Can I recreate the look of the splatters in the image to at least 90% realism with RF?
- I work in c4d, but would get the standalone if it is much better or can handle this type of scene better. Can c4d version of RF do accurate small scale stuff like this?
- I've set up the most basic scene and when I shrink my emitter down to 10mm in diameter, it seems to behave badly with particles shooting out backwards. Can RF work at such a small scale?
- If RF can work at a small scale like this, what settings should I change to get the emitter to work like it does at a larger size?

Thanks in advance for any guidance you can offer.
Paul
Screenshot_1.png
Screenshot_2.png
Screenshot_3.png
oil treatment.png
Screenshot_4.png
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Scott Frizzle
Posts: 25
Joined: Tue Mar 06, 2018 5:58 pm

Re: Oil splatter on a small scale

Post by Scott Frizzle » Thu May 10, 2018 10:11 pm

Hello Paul, Scott Frizzle here. I'm actually the one who tried to help you out with this same issue over on the XP forum. The funny thing is, I almost suggested Realflow to you but thought that might be inappropriate for that forum. After sending you the XP file I was curious how this might work in RF|C4D so I actually ended up fiddling around with it, but I soon forgot about it. Here's the file I came up with; it's not a perfect recreation of those pictures, but it's a lot closer than anything that can be done in XP, and you should be able to tweak this and get where you need to go.

This is all pretty straightforward; the only little trick is that I'm controlling the friction on the cloth surface with a noise texture in order to have a few droplets stick to the cloth. Hopefully this is helpful! I'm very confident RF|C4D has the features you need to pull this off.
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Scott Frizzle
Posts: 25
Joined: Tue Mar 06, 2018 5:58 pm

Re: Oil splatter on a small scale

Post by Scott Frizzle » Thu May 10, 2018 10:37 pm

One more thing regarding scale: Opinions vary, but I've found that RF|C4D works better at larger scales than you are using in your file. You can still get the sim to behave as if it's on a very small scale by adjusting things like the time scale settings. I've had the best luck just building scenes around the default emitter sizes, and not worrying about real world scale.

Paul Szopa
Posts: 2
Joined: Thu May 10, 2018 8:47 pm

Re: Oil splatter on a small scale

Post by Paul Szopa » Fri May 11, 2018 3:22 pm

Hi Scott,

Thanks for the help...again. I really appreciate it. This already much closer to the results I need than what I could get with XP (granted I am brand new to XP also, so it might be me and not the software).
- Re: scale of scene. Do I need to make natural forces like gravity 10x if my scene is 10x the size what it should be? Or is there some formula you use to keep the physics right?
- I'm not seeing the noise texture or understand how that would work. The rustic fabric.jpg is missing from the file. Is that what you're referencing?

I'm going to keep experimenting and see if I have any more questions.
Paul

Scott Frizzle
Posts: 25
Joined: Tue Mar 06, 2018 5:58 pm

Re: Oil splatter on a small scale

Post by Scott Frizzle » Fri May 11, 2018 7:02 pm

Oops, I accidentally got rid of the texture that was controlling the friction. Before sending the file I did a "remove unused materials" command and since that texture wasn't directly applied to any objects, it was deleted. Here's another file that includes the material that is controlling the friction. It's a noise shader in the luminance channel of the material, so you can change the noise and it will alter the friction behavior.

Regarding scale, I would just concentrate on getting the general behavior you want without changing the gravity, etc. to "match" the scale. You can then alter the speed of the sim using the time scale option in the scene object if you want things to move faster or slower.
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