Creating vacuum/suction?

Stianbl
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Creating vacuum/suction?

Postby Stianbl » Mon May 30, 2011 12:10 pm

Hi guys,
How would I go about to make a simulation with a suction force?

I.E. A straw sucking the water out of a glass...

Thanks a lot in advance,
Stian Berg Larsen


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ChristianZ
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Creating vacuum/suction?

Postby ChristianZ » Mon May 30, 2011 1:30 pm

Hi !

a vacuum in the proper sense is not possible to simulate with RF. But we have different daemons to do that. You could use a gravity daemon pointed upwards, if the liquid comes out of a closed bottle or similar container (or you use an invisible lid).
Or you could do a reverse animation and simulate the liquid coming out of the straw. An attractor daemon is less useful here, because its action depends on the distance.
RF10 standard + RFC4D

Stianbl
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Creating vacuum/suction?

Postby Stianbl » Tue May 31, 2011 5:54 am

Thanks a lot for your reply =)

I'm not sure a reversed gravity would be a good idea in my example, but thanks for opening my eyes to thinking in more than one ordinary way =)

In my example I'm going to demonstrate the Bernoulli's principle in regards to oil production, and the use of an RCP valve.

To first show the problem of not using a valve like this in extracting oil, we will show a glass of water with a straw in it. This straw has 5 holes in it, all bellow the water level in the glass.

We then start to suck out the water ("oil"), and as soon as the first hole gets over the water level and starts to suck in air we're going to loose the pressure.

I probably wont need a realistic simulation to mimic this, but it would greatly increase my knowledge in RealFlow if I did understand how to do this kind of simulation.

Any pointers would be great =)
Also, I fail to find more advanced tutorials for RealFlow out here on the internet. I'm willing to pay for good teaching in RealFlow, as we really need a person who can manage simulations well in our business. Once I feel I can produce good enough results for us to use we'll invest in a separate simulation machine for me, as our renderslaves are optimized for rendering, not simulation. If someone could recommend any systems here that would also be great, otherwise I'll just do some searches and see if I can come up with something =)

Sorry, lots of text.. But thanks for all the help! =)

Stianbl
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Joined: Tue May 10, 2011 10:54 am

Creating vacuum/suction?

Postby Stianbl » Tue May 31, 2011 7:54 am

When importing from max it's way too big.
If i scale it down in the properties settings nothing changes. If I scale it down using the scale options it gets smaller..

But now, I need the resolution to be at 1000 to get details and enough particles.

However, at res 1000 the emitter spawns particles everywhere. it's coming out of the top of the emitter, and going out on the sides, as if the pressure was way to high. But at res 100 it works fine.

But res has nothing to do with pressure, or velocity?

//EDIT

Also, what is the workflow for creating objects in max, and exporting to RealFlow?
We use Meters/Inces in max, and this does not work with RF, right?

So I set max to meters/meters.. But now, if I want to create a cup 10cm high and 5cm in diameter, it's almost impossible to work with in max..
And scale is off in RF even now.

Setting the geometry scale in the properties in RF to 0.01 doesn't help, and setting it to 0.01 in the scale options makes it smaller, but now simulations doesnt work properly.. Gah.. =P

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ChristianZ
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Creating vacuum/suction?

Postby ChristianZ » Tue May 31, 2011 8:54 pm

What you are describing are the typical scale issues that are discussed in several threads here on the forum for years. I am not a Max user, but usually you have a standard factor between RF and your 3D application of choice (for Cinema4d users this was until recently 0.01 because the program did not recognize real units) that you could use if you want to fit objects and liquids after import of the bin-meshes without re-scaling. Once you have found a workflow that works for you it is not such a big hassle anymore :cool:
RF10 standard + RFC4D

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bitSeq
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Creating vacuum/suction?

Postby bitSeq » Wed Jun 01, 2011 8:52 am

For max to RF you need to use a scale of .01, the reason that your geometry was not working was probably due to your collision distances, these are not changed when you adjust the scene scale, so your collision distances are probably huge... like 100 times so.

Stianbl
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Creating vacuum/suction?

Postby Stianbl » Wed Jun 01, 2011 10:29 am

Thanks. That sounds like a probable problem.. =)
Any tips on what collision distance should be set to? Or any other parameters to have in mind?

As soon as I get to know all the basics like scale I think I'll manage to play around and learn a lot.

I do know hybrido, but I really lack in working with daemons.. So once I fully understand the scale, and what parameters to have in mind, I think I'll do a lot better. =)

Thanks for all the help, and please let me know how to get started properly =)

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bubs
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Creating vacuum/suction?

Postby bubs » Wed Jun 01, 2011 11:40 am

Look at my Blog or just send your questions in Skype
I'll dry to help you
Cheers
http://www.bouchakour.de/
http://vimeo.com/user493010
http://fluidartist.blogspot.com/

Stianbl
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Creating vacuum/suction?

Postby Stianbl » Wed Jun 01, 2011 12:09 pm

Thanks mate =)


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