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Blender Fluid Simlulation Parameters Comparison Video |
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Written by Thomas Kropf
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Thursday, 05 March 2009 |
Blender is a 3D modeling application that's also capable of doing Fluid Simulation. So I looked into that recently and made a few tests with different values for "resolution" and "real-world size". The outcome is a short video (including crappy music made by myself) and some conclusions.
Objects The scene consists of 3 different simulation objects. Domain
The domain is a simple cube which describes the borders of the simulation. In the beginning of the video you can see it because I put a green grid on it. Fluid
The fluid is a cuboid that is flashing red in the video. Obstacle(s)
You can see two obstacles in my video. The first one is a rectangular bucket, a reservoir, a tub or whatever you call it. It is stationary and is simply there to hold the fluid. The second one is a tiny cube that moves along a path/curve. I added it to make the simulation interesting. Without it, the fluid you just sit there (in the big obstacle) and wouldn't do much. Parameters Resolution
I tested a few different values for the "resolution" parameter. A value of 50 really looks awful, almost like mud. There are huge gaps between the obstacles which makes it pretty much unusable. A value of 100 is better but it's still too inaccurate. A value of 200 however looks, in my opinion, very good. The splash looks very nice and the gaps between obstacles are hardly noticeable. I also tried a value of 400. But that filled up all of my 8 GB of RAM and when it also started to fill up my swap partition I sadly had to cancel it. Real-World size
According to the Blender Fluid Manual the Real-World size parameter denotes "the longest side of the domain bounding box" and represents the "size of the domain object in the real world in meters". I tested values 3, 0.3 and 0.03 (=default value). So in my scene a value of 3 meters means that my reservoir is like a small swimming pool. A value of 0.3 (=30 centimeters) could be compared to a (rectangular) bucket and 0.03 (=3 centimeters) could be something tiny like a thimble.
Real-World size 3: The splash looks really massive and almost half of the water flies out of the reservoir.
Real-World size 0.3: The splash is a little smaller and the water looks finer. You can even make out single drops forming on the obstacle.
Real-World size 0.03: There is no real splash anymore. The moving cube only pushes some of the water out of the reservoir. You also can see single drops but it looks pretty boring. Conclusion A resolution below 200 is almost useless. I would only use it for preview purposes.
The Real-World size parameter is rather tricky. It has to be set depending on what effect you want to achieve. I guess it's pretty realistic so if you want to simulate a pool then use 3, if you want to simulate a bucket use 0.3 instead. The blender default value of 0.03 seems pretty useless to me. I wouldn't use it if I were going for something spectacular.
Be sure to activate HD to enable youtube's High Definition mode! |
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Last Updated ( Thursday, 05 March 2009 )
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