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Air flowing through a room and leaving trails behind


Octavia89

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Hi everyone!

The other day I saw an interesting thread in the Cinema 4D forums. It was about simulating air flowing through a room or cave and leaving trails behind. I fetched the pictures that were posted there.
I am intrigued. My question is whether it is a big deal to make a simulation like this in Houdini?
For a newbie that is. I have just recently picked up Houdini.

Kind regards,
Octavia

flow01.jpg

flow03.png

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I think it highly depends on what you mean by "simulating". That is, A "getting a look like the one in the picture" or B "predicting the actual airflow to an arbitrary degree of accuracy". A is relatively easy. Take a look at "Volume trails", they will give a look exactly like that. B is probably much harder and would probably involve some deeper research. Check the hip for a crude version of A

 

quasi_airflow_odf.hip

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Hi Vitor, thank you for your suggestion. Pardon me, you are right. I think what I mean tends more to be something in between A and B, more precisely making particles fly through a tunnel or cave or pipe in an orderly manner, have them a) respecting the boundaries of the geometry while flying through or b ) defining the model contours with curves along the entire geometry and use them as hoops for the particles to fly through (see picture). I believe this is possible with the particle plugin in Cinema 4D. It sounded easy in Cinema 4D...

I am trying to understand your hou file. Obviously, the A approach seems very quick and elegant. There are some nodes or steps that I do not understand yet. 
Is this what you did ...in layman's terms?
Create an object, create a volume/cloud, define object as border of volume
evenly distribute points in volume with direction (how?), connect those points with curve (how do you define the point order for a curve to pass through?)

Can you apply this setup to a tube-like structure with indentations a couple of bends?

 

hoops.jpg

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Sorry, I should've commented the file.

 

I'm creating a smoke simulation, with a tube for the smoke to collide inside. Then I'm using the volume trail node to visualize the velocity of result of that simulation. The Volume trail nodes works by creating a polygon at every point you feed to it based on the velocity of the volume at that point. See this 

He explains it in the first 5 minutes

About the curved tubes, I think so yes, as long as the smoke moves properly. Depending on what you want, you might not even need to simulate it at all, just sculpt the volumes. He does something like that around 30min. 

 

 

 

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Hello Matt. These are the screenshots of the thread. Obvioulsy, you can make the particles jump through hoops made of curves. Somehow it doesn't work in his example, he's using custom curves. 

As far as I can see three approaches have been discussed.

1) make particles jump through curves which are layed out on a path

2) particles move through geometry, the geomtry is set to "avoid", it repells particles

3) particle flow are redirected with direction nodes

all particles have trails

thread 03.png

thread 02.png

thread 01.png

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@Vitor

I appreciate you explaining the file, thank you.

I watched the tutorial by Simon Fiedler and have a question. What do you mean by he sculpted the volume?

Do you mean "sculpt" like it is done in ZBrush or Mudbox? Or is it she curve he drew (and tangents he extracted) in the beginning, which shapes the volume?

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