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Everything posted by nigelgardiner

  1. Hi Ryew Yep pouring a volume of fluid through a spout is definitely an improvement on emitting from a source volume. I'd tried emitting from a source volume thru a spout before and it didn't really work but pouring a bottle or glass of fluid starts to give a better shape. The paper Marty attached above explains the Navier Stokes equations pretty well. Using a spout defines a solid boundary for the time the fluid is moving thru it but then it's defined entirely by a free surface when traveling thru air, surface tension is the major factor here, (thanks Marty) and I think that's able to be defined by mean curvature which you can solve for with gas analysis micro solver, and then, well I'm still figuring that out. I read the Flip smorganic/sheeter effect thread last, Pazuzu's tension work was amazing. Haven't got a flip worth sharing at the moment but will do.
  2. Hi there I'm trying to determine an approach to shaping an emitted flip fluid pour. When you look at fluid poured from a bottle or a jug there's an awful lot going on in the way the fluid surface behaves. it very nicely rolls i guess (not the best description) into itself from the sides and tapers in on itself the further away it is from the top of the pour. It's a really beautiful shape. I should imagine the physics of it is pretty complicated but does anyone have any ideas about a basic plan of attack or know of any documentation that discusses this? I've had a hunt around but don't seem to be able to find anything. I guess I want to be looking at curvature and/or surface tension or something like that and manipulating the velocities on the particles at the edges of the pour relative to those at the centre? Any advice much appreciated, this is just a learning exercise at this stage. thanks Nigel.
  3. Hi there I've been looking into seeding vorticles and I like the idea but I'm not sure whether they could be used in a flip network and even less sure what I'd plug the gas vorticle geometry node into? Any ideas? I'm thinking it'd be like adding impurities into your liquid. thanks Nigel.
  4. Hi there I've been looking into seeding vorticles and I like the idea but I'm not sure whether they could be used in a flip network and even less sure what I'd plug the gas vorticle geometry node into? Any ideas? I'm thinking it'd be like adding impurities into your liquid. thanks Nigel.
  5. you could using density to separate the different components, that'd make flip layer them by density and apply different forces to them to create the mixing. might be too crude for the behaviour you want to create tho cheers Nigel.
  6. I want to emulate the flow of liquid from the neck of a bottle as per the attached image and out of interest I'm trying to determine how I could control the way it shapes. Sorry I don't know what you call whatever is happening in terms of physics but the liquid in that shot (and real life pours in general) has such a nice shape and taper to it. To date I haven't been able to achieve anything close. I did try and cheat it with noise on the velocities from the emitter volume but that looked terrible. Quickly looking at the fluid notes Marty sent thru earlier, there seems to be a few relationships that could be useful but it's going to take a close read for me to understand it, if i even can. cheers Nigel. pour.tiff
  7. Hi Marty Thanks, I'm already using the swirly kernel. And ta for the fluid notes, much appreciated. Have a good day.
  8. Thanks Ryan.
  9. Hi So I'm looking into solving my issue with a glass of flip collapsing after the emission stream ends. Atom suggested adding a divergence volume so I'll have a look at that but I'm wondering what the difference between using a source volume for divergence and using divergence by attribute on the solver itself is? Also I'm wondering if anyone knows of any documentation describing how to use the pressure and divergence fields in flip? Thanks Nigel.
  10. I have shortcut failure H16.0.670 Ubuntu 16.04. yep frustrating.
  11. maybe when there are inter dependencies within in it that would be better separated. which makes things easier to change. say for example a dop network containing related flip, pop and smoke solvers, it seems to make sense to run them as three separate networks so if there is an issue/change with one part of the network you only have to re run that dop.
  12. that's cool. on a side note, how do you embed the video in the post like that? when i try i just end up with the < code > sitting there.
  13. Just guessing but I think the fetchdata node will take a mask on the rh greeninput, you're bringing in essentially a mask with your sop scalar field, so I think you can just plug that into the fetchdata node?
  14. Hi There Attached is a link to fizzy fluid, my attempt at creating a fluid which fizzes and foams, in this instance it's beer. It's very much a work in progress and low sample render, there are issues that need correcting and features to be added but I thought it was time to get some feedback. Simmed in Houdini 15, rendered in Houdini 15 , Mantra using the Phy Shader. thanks Nigel. https://vimeo.com/210682852
  15. Hi Hamp I'm a photographer, so for the last twenty years I've been trying to take the blur out of high speed fluid shots, I need to get my head around motion and blur. I'm sure you're right. Re the bubble velocities, yeah they are meant to be advected around inside the fluid surface with a general upward trend. The upward velocity was too large in proportion to the advect velocity and I think I don't have enough swirl in the vel field for the advection. I can't use the flip vel field to advect the bubbles as it doesn't really have the right motion so I build a smoke volume out of the flip surface each frame, move that around, and use that to generate a vel field for the bubble advection. It's possible I have an issue here as well, need to check that. cheers Nigel.
  16. Hi Hamp Thanks. There's a few things I still need to work on but I'll do a higher sample render and try some motion blur next render out maybe. cheers Nigel.
  17. Hi There Please find fizzy fluid mk3. thanks Nigel. not sure why i can't get the embed code to work sorry. https://vimeo.com/227575401
  18. <iframe src="https://player.vimeo.com/video/227575401" width="1280" height="720" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>
  19. Hi There I'm writing out a .sim file for every frame of my simulation and would like to restart the simulation from a given frame number but I don't seem to be able to do this. I have the .sim file path and name entered as the initial state but if I press play or jump into the dop network and save to disk from the given frame number Houdini wants to start at frame 1 and re sim all the way thru. Am I missing a step here? As every frame is a .sim file I was assuming I wouldn't need to save checkpoint - am I wrong about this? thanks in advance. cheers Nigel.
  20. So you've set the initial state parameter on the dop network? One other thing I noticed, is it appears you can't alter the hip file and be able to re use the sim files even if the change is not related in any way to the generation of the sim files. I may be wrong about that but I couldn't get it to restart. In my case, I had sim files for each frame and an initial state loaded but when I started the re sim it began at frame 1 again. In the end I gave up assuming rightly or wrongly that it was because I'd made a change to the hip file. There is another post around describing the process someone else went thru to restart a sim in Houdini 16 but I can't for the life of me find it right now. There are a few posts around to describe how to restart a sim but they refer to an explicit cache which I think is now replaced by checkpoints? Sorry I can't be of more help and I hope I haven't confused the issue. good luck.. nigel.
  21. kick it and see if it moves.
  22. Hi Dave Thanks for that link. There's a link to a github for download of a new stokes microsolver which sounds like it could address your issue. cheers Nigel.
  23. have you tried increasing the sub steps on the solver when you turn viscosity on? Machine tied up but I'll have a look at your hip when i can - that's an interesting artifact. cheers Nigel.
  24. No, no Houdini directory. nigel@user-PC:~$ echo $PATH /home/nigel/bin:/home/nigel/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin thanks Nigel.
  25. Hi There I have Houdini 16 running on Ubuntu 16.04. Now I need to install a daily build. Could someone tell me the easiest way to go about this please? thanks Nigel.