Dspline to get a ribbon

Discussions about the use of Realflow
angel_airlines
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Joined: Thu Jan 18, 2018 11:16 am

Dspline to get a ribbon

Postby angel_airlines » Thu Feb 01, 2018 8:17 pm

Hi guys,
I’m using a Dspline to flow a fluid around a bottle but I’m getting a rounded (cylindrical) shape as result.
I think is the drag daemon that is rounding the fluid, with a thinner start and end of the stream, and I’d like to get a more flat stream.
I’m using DSpline, Drag and a noise daemon (quiet low value on the noise)

Is there a workaround to maintain the fluid more planner during the dspline flow?

Thanks is advance


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ChristianZ
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Re: Dspline to get a ribbon

Postby ChristianZ » Sat Feb 03, 2018 12:09 pm

Hi

a more ribbon-like shape could be obtained by using a linear emitter at the start of the Dspline and a relatively high "vortex strength". However, it is always a delicate balance between the vortex strength (which produces the cork-screw motion of the ribbon) and the "radial strength" (which moves the fluid forward along the spline). The perfect ribbon would be made by a linear emitter with low internal and low external pressure removing fluid properties, without drag or surface tension. But at the end of the day it is no longer a fluid simulation and you could be better off with a cloth simulation or other standard particle systems without fluid physics.
RF10 standard + RFC4D, System specs: OSX 10.11, MacPro 4.1 2xXeon, GTX980Ti, 64 GB RAM

angel_airlines
Posts: 48
Joined: Thu Jan 18, 2018 11:16 am

Re: Dspline to get a ribbon

Postby angel_airlines » Sun Feb 04, 2018 8:18 pm

Hi, thank you for your answer.
yours is a clever approach, but I still can't avoid the fact that the Dspline radial strength is gonna transform the linear particles emission in a cylindrical fluid right away as it gets influenced by the radial or vortex (or both).

The get a better approach of the effect, if I use a spline emitter and the spline used is a helix and I set the mode of the emitter to "Axis", I manage to get a fluid that is not rounded but flat (and this is what If like to achieve as fluid shape) and it doesn't have the first part of it (first particles) like compressed by the spline. Unfortunately using this method I can make the particles travel across the helix, as they are created at the same time all across it.

Basically, I want to avoid the particles to be flatten as the cross the fist Dspline circle...

I have attached a image of the spline emitter.

Thank you.

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ChristianZ
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Re: Dspline to get a ribbon

Postby ChristianZ » Sun Feb 04, 2018 11:42 pm

Hi

yes, I see the problem... the beginning of the Dspline almost always acts like a "lens" that attracts the particles and pulls them together.

An alternative approach could be to move the linear emitter along a spline such that the emitter leaves the ribbon behind, without Dspline.
RF10 standard + RFC4D, System specs: OSX 10.11, MacPro 4.1 2xXeon, GTX980Ti, 64 GB RAM

angel_airlines
Posts: 48
Joined: Thu Jan 18, 2018 11:16 am

Re: Dspline to get a ribbon

Postby angel_airlines » Mon Feb 05, 2018 8:49 am

Hi,
thanks for your answer, but now I can see how I will maintain the particles then attached to the spline, without flying away, as the emitter travels along the spline.

Do you think (I haven’t try yet) the “Spline Emitter” would do the job?
I think I saw in one of those LearnWaterDesign workshops the case study of Coca Cola with similar results.

Cheers,

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tsn
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Re: Dspline to get a ribbon

Postby tsn » Mon Feb 05, 2018 9:13 am

You can also try that freebie: http://waterline.tv/downloads_03.html. Just look for the "Fluid Ribbons" chapter ;)

This project requires a script that's listed in the magazine as well. This script is responsible for the emitter's orientation along a spline/animation curve. If you don't want to use a script you can also animate the emitter by hand. In any case, the description shows you how to calm down your particles and make them stay in the air.

angel_airlines
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Re: Dspline to get a ribbon

Postby angel_airlines » Mon Feb 05, 2018 9:36 am

Brilliant!
Thank you very much

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ChristianZ
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Re: Dspline to get a ribbon

Postby ChristianZ » Mon Feb 05, 2018 9:55 am

Thanks Thomas!

How could I forget it..always check the waterline pdfs and the blog for in-depth RealFlow knowledge <thumbs up>
RF10 standard + RFC4D, System specs: OSX 10.11, MacPro 4.1 2xXeon, GTX980Ti, 64 GB RAM

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tsn
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Re: Dspline to get a ribbon

Postby tsn » Mon Feb 05, 2018 10:06 am

ChristianZ wrote:How could I forget it..always check the waterline pdfs and the blog for in-depth RealFlow knowledge


;)

angel_airlines
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Re: Dspline to get a ribbon

Postby angel_airlines » Mon Feb 05, 2018 10:29 pm

I have been simulating with the paint ribbons script quiet a lot today and I get what I was looking for, but it will look more realistic if I can get some particles not to be so attached to the main flow...
I tried adding noise falled-off daemons along the spline to get some trendils (I think it will look more realistic) but the drag daemon stick the particles so much that the particles can´t escape its force...

any idea will be helpful.

I could add a screenshot of my mainstream tomorrow if you need to see exactly how it looks.

Thank you anyway... I don´t think I could have get any better approach anyhow.

Cheers


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