working with "blender" to simulate "fluid dynamics" making a "numerical wave tank"
June 6, 2008 at 2:30 pm #577
On Linux there is some free software called “blender” that can do really nice 3D simulations, including fluid dynamics. I don’t know of any other free software that is closer to a numerical wave tank for visualizing results. Does anyone? For examples see:
(first I was not sure this was a simulation, but there are no bubbles)
(not just limited to normal laws of fluid dynamics)
Not sure the above is fluid dynamics. You can just define wave motion in blender without simulating the physics of water. But the ocean looks cool and it has a boat on it so I am including it anyway.
This last video has a boat in a wave tank. I think he had the top of the area the water could go to so low it was hitting the top. Also, this was 2 years ago and blender has been improving. This video shows the idea of testing something in a simulated wave tank. I think it is possible to do much better than this now.
Here is a simulation of boat with a prop pushing in a wave tank. This in the kind of thing, but with waves.
This is of a lighthous on a tiny island with a big wave hitting it. This is very close to the kind of simulations I would like to see for seasteads. But deep ocean waves not shallow water waves.
At the moment it is not easy to setup a “numerical wave tank” and test some ocean structure. But it can be done. If someone setup a simulation we could all use it. And judging from the cool 3D pictures people have made, I am sure we have people here who can do this.
Also, blender is open source. We have programmers in this group. It would be possible to make it “wave tank test friendly” where users could enter a few parameters and do some tests. Would make it much easier/cheaper/faster than building models and paying for a real wave tank. So things could move along faster.
Ideally you could draw something in Google SketchUp and then drop it into a blender simulation to test how it works and make a cool video. Then post the video on youtube so everyone can see the results. For rigid structures I think this should be possible. Would need to be able to specify the density of the different parts. If you have lead ballast and aluminum structure you have to let blender know both of these. I am not yet worried about testing the strength of the structure, just the stability when interacting with waves.
Seems you can import SketchUp objects into blender:
Seems like a good project for people here to work on. It is a way to use the computer skills we have in this group to attack the ocean engineering problem. The resulting system would be good for seastead research and for other people too. Do people like this idea? Or do we just want to use real wave tanks? Are there people here with the time, skills, and inclination to make blender work for us?
If nobody here wants to do it, maybe the Seasteading Institute could fund one of the blender developers to make an easy to use numerical wavetank so we can just draw something in SketchUp and then simulate it in blender under different wave types? For someone familiar with blender what we need is probably not that hard to create. So it probably would not cost too much.June 21, 2008 at 8:42 pm #3286
June 24, 2008 at 4:11 am #3327
- This seems very promising. There weren´t a lot of simulations of floating things though, but I guess it can do that correctly as well?
- Blender is available for Windows as well as Linux, just FYI.
Our understanding is that there is standard CFD (Computational Fluid Dynamics) software used by the ocean engineering industry. I don’t think they use blender tho’.June 24, 2008 at 5:40 am #3330
If the standard CFD software costs $10,000/user we might still be very interested in using the free “blender” software. What do they use and how much does it cost? Also, blender was not so powerful just a short time ago. So it may just be tradition that they use what they use, not that it is better. Also, even if the standard software is in some ways better, there might be important features that make blender better for us. For example, blender can import a Google SketchUp drawing, if the other software can’t I might choose blender just because of that.August 17, 2008 at 11:52 pm #3598
I am a blender user!
http://wiki.blender.org/index.php/Manual/PartX/Fluid_Simulation It says what kind of formula it uses somewhere there (been a while since I read it), but I imagine it doesn't the standards, and if it doesn't it is open source you can hire someone to make it better and then share the source code with the blender community, which is cheaper then paying for a Properitary App. **Also the first one you think that might not be a simulation isn't. So you know how powerful blender is check out the short movies, Big Buck Bunny, and Elephants Dream. Should beable to find 1080p copies out there, free to download. sincerly me. ps I might be able to help with blender stuff, feel free to email me. firstname.lastname@example.orgMarch 12, 2009 at 2:39 am #5161
My firm uses CFD. If I see a reaonable application for it, we’ll pitch in. I’m still learning this project. However, boyancy is another issue, as is sloshing. There are other codes out there that allow for very complex water action modeling…and they are more expensive.
Realistically, at some point these will be needed to do proper due dilligence to have reasonably design for safety and reliability.
Bart Kemper, P.E.March 25, 2009 at 8:23 pm #5301
I posted in the Engineering section, but I’ll repost this here. I’m a professional CFD engineer and am willing to do some work in my spare time.
While blender makes beautiful movies, the fluid engine is not a realistic engine. It is designed to produce motions that look like real fluids to the human eye without all the pesky overhead of actually calculating a realistic solution.
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