Re: [Bf-committers] Fluid particles refactoring
On Mon, 21 Feb 2011 04:53:46 +0200, Alex Fraser adfr...@vpac.org wrote: We have been using the SPH solver for engineering simulations. In our experiments, we often vary the fluid interaction radius independently from the collision radius. For example, if the size of a hole in a container mesh changes, I might want to make the collision radius smaller. Then again, it might make sense to make the interaction radius smaller too, so that the particles still flow nicely through the hole. I suppose what I really want to do is change the resolution of the simulation without drastically changing the way the fluid behaves (e.g. double the number of particles, but maintain the same volume). If you can acheive this by changing the rest density at the same time as the interaction radius, I'm all for it. Will there be a way to find out what the interaction radius is, for the sake of writing reports? Also, what will the Advanced Rest Length setting do? Partly thanks to your comments and some other people I've slightly changed my plan now and I do intend to include an interaction radius parameter in the advanced section. However I'll also add an additional setting to multiply interaction radius with particle size, pretty much like the current setting to multiply mass with size. By default this option will be on, so that it's easy and intuitive to start, but if you want to do it the old way then that will be possible too. In my current code the interaction radius is 4.0*particle size, which seems to give quite natural results (this will include nearest neighbors at distance 2*size and just barely the next ones at distance 4*size in the sph calculation). The spring rest length is 2.0*particle size, and the advanced rest length parameter is just a multiplier for that default length. One big challenge for us has been finding out how the parameters presented in the UI relate to physical quantities. The information doesn't seem to be available in the paper the Blender SPH code is based on: http://www.iro.umontreal.ca/labs/infographie/papers/Clavet-2005-PVFS/ Perhaps the simulation in Blender is unphysical. We intend to implement a classical SPH algorithm, i.e. one without the double density relaxation, to perform further experiments with. We expect it will be more physically accurate (although perhaps lacking surface tension), and easier to make multi-threaded. Yes the whole approach taken in the paper is pretty unphysical (or at least not at all concerned with the physical quantities of fluids) and I think in a sense that's good as it's designed to be nice system to play with without having to check physical values from somewhere. Of course it would also be nice to be able to do physically correct simulations, and hopefully the changes I'll make will make it a bit easier to test other sph implementations too. janne ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
so mine :) 2011/2/19 Mats Holmberg mats.holmb...@2me.fi On 19.2.2011, at 20.20, ra...@info.upr.edu.cu wrote: Is on the way ;) This comment really made my day =D Thanks. -mats ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers -- François Tarlier www.francois-tarlier.com www.linkedin.com/in/francoistarlier ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
On Sat, 19 Feb 2011 00:57:39 +0200, Michael Fox mfoxd...@gmail.com wrote: i don't like how size is now being used as ui tend to use size deflect with some random size which means if i increase the size, hence the radius then the particles will float above the collision object. I've used size deflect in pretty much all my fluid tests and using particle size to influence the interaction radius too only seems natural to me. Perhaps I didn't make it clear enough that the idea is not to have interaction radius = particle size, but that the size defines a sensible radius so that enough neighbors are included in the calculations (for example 4 * size). So I don't quite get how this would make the particles float above the surface.. but can you please explain your work flow a bit more so I can understand the problem? On Sat, 19 Feb 2011 01:11:28 +0200, Carsten Wartmann c...@blenderbuch.de wrote: BTW: Is there a documentation in one place for all the new particles? Even in your blog it is hard to keep track. Yes the existing documentation is quite outdated. Once I get these changes ready I'll make a proper tutorial or perhaps even a couple on how to use the fluids in different cases, so that will hopefully help to get you started. And yes I do know that this will break old simulations, and that you book writers have to do some pages all over again, but my sincere intention is a better user experience with the particle fluids, so please forgive me. See above ;-) Beside us writers I don't think there is much use of them at the moment beside self contained demos and some effects, so I think it is acceptable to break some old simulations. This is very nice to hear :) And yes like Raul said surfacing is being worked on by him and Stephen, so hopefully we'll have some really usable fluid particles before the 2.6 is out! :) janne ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
Am 20.02.2011 16:27, schrieb Janne Karhu: On Sat, 19 Feb 2011 00:57:39 +0200, Michael Foxmfoxd...@gmail.com wrote: ... hopefully we'll have some really usable fluid particles before the 2.6 is out! :) Erm, the next release is 2.5x I am not wrong, and Roland is not a clairvoyant ;-) So you got 1 or 2 years ;-) Carsten, hopes you meant 2.5x -- Carsten Wartmann: Autor - Dozent - 3D - Grafik Homepage: http://blenderbuch.de/ Das Blender-Buch: http://blenderbuch.de/redirect.html ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
Hi Janne, Thanks for putting together this proposal. - Original Message - I've been refactoring the fluid particles recently, and before I actually start getting ready to commit this I'd like to get some feedback on my current progress and ideas. http://code.blender.org/index.php/2011/02/particle-fluids-refactoring-under-way/ We have been using the SPH solver for engineering simulations. In our experiments, we often vary the fluid interaction radius independently from the collision radius. For example, if the size of a hole in a container mesh changes, I might want to make the collision radius smaller. Then again, it might make sense to make the interaction radius smaller too, so that the particles still flow nicely through the hole. I suppose what I really want to do is change the resolution of the simulation without drastically changing the way the fluid behaves (e.g. double the number of particles, but maintain the same volume). If you can acheive this by changing the rest density at the same time as the interaction radius, I'm all for it. Will there be a way to find out what the interaction radius is, for the sake of writing reports? Also, what will the Advanced Rest Length setting do? One big challenge for us has been finding out how the parameters presented in the UI relate to physical quantities. The information doesn't seem to be available in the paper the Blender SPH code is based on: http://www.iro.umontreal.ca/labs/infographie/papers/Clavet-2005-PVFS/ Perhaps the simulation in Blender is unphysical. We intend to implement a classical SPH algorithm, i.e. one without the double density relaxation, to perform further experiments with. We expect it will be more physically accurate (although perhaps lacking surface tension), and easier to make multi-threaded. Cheers, Alex -- Alex Fraser Software Engineer The Victorian Partnership for Advanced Computing ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
Hi :) Sounds great! I am just at particles chapter for my book an was not sure to include fluid particles at all, it is (was?) quite hard to get nice simulations, they tend to explode to often with no (for me) obvious reason. That explode thing is long in the past, Jahka has improved a lo the stability so now is pretty easy to get nice simulations However, I have not so much real use for them until we have a mesh tesselation for them. Suggestions welcome. Is on the way ;) ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
On 19.2.2011, at 20.20, ra...@info.upr.edu.cu wrote: Is on the way ;) This comment really made my day =D Thanks. -mats ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
Am 19.02.2011 19:20, schrieb ra...@info.upr.edu.cu: Hi :) Sounds great! I am just at particles chapter for my book an was not sure to include fluid particles at all, it is (was?) quite hard to get nice simulations, they tend to explode to often with no (for me) obvious reason. That explode thing is long in the past, Jahka has improved a lo the stability so now is pretty easy to get nice simulations I always use a daily build. So completely it is not past... However, I have not so much real use for them until we have a mesh tesselation for them. Suggestions welcome. Is on the way ;) Great, but I guess too late for my book. So far it is usefull for such kind of stuff: http://www.youtube.com/watch?v=U_azkgb5mXM ;-) Carsten -- Carsten Wartmann: Autor - Dozent - 3D - Grafik Homepage: http://blenderbuch.de/ Das Blender-Buch: http://blenderbuch.de/redirect.html ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
i don't like how size is now being used as ui tend to use size deflect with some random size which means if i increase the size, hence the radius then the particles will float above the collision object. On Sat, 2011-02-19 at 00:23 +0200, Janne Karhu wrote: I've been refactoring the fluid particles recently, and before I actually start getting ready to commit this I'd like to get some feedback on my current progress and ideas. http://code.blender.org/index.php/2011/02/particle-fluids-refactoring-under-way/ And yes I do know that this will break old simulations, and that you book writers have to do some pages all over again, but my sincere intention is a better user experience with the particle fluids, so please forgive me. I'll gladly read and respond to feedback either here or in the post comments! janne ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
Re: [Bf-committers] Fluid particles refactoring
Am 18.02.2011 23:23, schrieb Janne Karhu: I've been refactoring the fluid particles recently, and before I actually start getting ready to commit this I'd like to get some feedback on my current progress and ideas. Sounds great! I am just at particles chapter for my book an was not sure to include fluid particles at all, it is (was?) quite hard to get nice simulations, they tend to explode to often with no (for me) obvious reason. However, I have not so much real use for them until we have a mesh tesselation for them. Suggestions welcome. BTW: Is there a documentation in one place for all the new particles? Even in your blog it is hard to keep track. And yes I do know that this will break old simulations, and that you book writers have to do some pages all over again, but my sincere intention is a better user experience with the particle fluids, so please forgive me. See above ;-) Beside us writers I don't think there is much use of them at the moment beside self contained demos and some effects, so I think it is acceptable to break some old simulations. Carsten -- Carsten Wartmann: Autor - Dozent - 3D - Grafik Homepage: http://blenderbuch.de/ Das Blender-Buch: http://blenderbuch.de/redirect.html ___ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers
