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Found 621 results

1. ## Add liquid / particles to a flat tank simulation

What is the best workflow for adding particles / liquids to a flat tank simulation setup. Think of barrel that is spilled or a hose that is pumping new liquid into a flat tank simulation. I somehow figured out how to add some volume velocity into my tank but can't quite understand how to create or spawn new particles into it. Being a beginner I would appreciate a thorough explanation. Thank you.
2. ## Control forces by conditions

Hey I had this come up a few times today and I was wondering what was the best way to tackle it. I am doing a melting sim of an object thats floating in space. I am using temperature to heat the FLIP and start the melting process. if use gravity then the whole thing starts moving from the start and not just the heated parts. I was thinking if I could just apply the forces based on temperature then that would would be ideal. I tried something like this in the pop wrange but its giving me erratic results. float hot = @temperature; if (hot>1) {@v *= 3;}; Also whats the equivalent of the the geometry spreadsheet in dops, if I wanted to see the values of the temperature or any attribute. I can visualize as color but would be nice to get some numbers. Cheers!
3. ## Flip slow motion or bullet time update?

Hi everyone, I have been looking to create slow-motion flip sim using a narrow band tank and dropping an RBD object into it. I have seen older advice like this from Atom about adjusting the Time Scale inside the Flip solver: https://vimeo.com/121376943 But when I followed the instructions it doesnt seem to work - as its many versions old from the current H18 there could be a lot of reasons for this. Does anyone have any up to date information of how to achieve this? Currently I am going round in circles adjusting the Velocity Scale and Time Scale in a never ending fight to get it to slow down correctly but also maintain the splash velocity. I cant seem to get the flip sim to match the Time Scale of my RBD at all, the flip is always moving way too fast. Any help would be great!
4. ## Problemn using Point Deform

Hello everyone ! I would like to deform a geometry by a fluid simulation using a point deformer. To do so, i plug my geometry and my simulation into my point deform and i use a Timeshift set up on the starting frame as the Rest PointLatice. But instead of following the simulation, it looks like the geometry tries to reach the world center, creating what looks like an unholy abomination. Any help or tip would be deeply appreciated Thanks in advance
5. ## How to increase particle separation for spray whitewater solver?

Hello! How to Increase Particle Separation for Spray - Setup whitewater solver?
6. ## 18272 Fatal error Segmentation Fault! - Flip HELP ME!!!

I am trying to render a simulation done with a flip which is made up of 22 million particles. After having made several attempts the houdini console throws me a: 9576: Fatal error: Segmentation fault Saving application data to .... Here below I leave the image and the project files in case someone is willing to help me. Thank you so much!! Help me please!!! Collider.obj Test.hipnc
7. ## ReSeed FLIP Only When Points Are Above Waterline

Hello Houdini pros! I'm using the FLIP Solver's Reseeding feature, but it doesn't seem to be applying enough reseeding in the areas that count. It is reseeding the entire FLIP tank, where I'm really only needing the detail in the splash. Current train of thought: Create group of particles that are above the waterline (my current method isn't great, as it groups all points above P.y 0.01) Apply reseeding only to that group. Have had a search around online and have found one person talking about this, but not how to impliment it. Any help is greatly appreciated! Reseed_Above_Waterline.hipnc
8. ## Flip sim splash gap between liquid and object

I have a scene where I am dropping a bottle into a flip tank all at small scale. The issue im having is that I am getting a quite a large space/void between the bottle and the liquid. Im trying to reduce this and make the liquid hug the bottle more in the beginning and not blow outwards and make this gap. The setup is an RDB of the bottle falling using gravity from around 10cm into the tank, both the RDB and Flip have been slowed down to 0.025 in time scale. I tried a number of things like lowering the velocity scale, upping the subframes from 10 to 30 in the RDB and upping the subframes in the DOP network to 4/5, and changing the surface tension and viscosity, but it still happens. There is no problem with the collision guide and I dont have any sort of surface offset on that either, it matches the bottle perfectly. You can see in the attached screen grabs that the bottle has barely entered the fluid surface but has created a large void underneath it blowing out the liquid. This is the sort of splash im aiming for: https://www.youtube.com/watch?v=npAuLi1y5AA Dramatic but close and not blowing out internally too much. I know my bottle is a different shape to that reference but my sim seems way off and I cant seem to figure out how to lessen that gap. Any suggestions I would be very welcome as nothing I seem to try is making the gap any smaller. Thanks!
9. ## FLIP torque, rotation, spin?

Hey guys, I have done a search but there are not many answers. How can I get a flip sim to have torque or self rotation? I have a slightly viscous, surface tension flip sim, kinda like paint flying through the air with sheets and thin streaks. I want some of the "heads or blobs" on the end of sheets and streaks to pull the fluid more than other bits, so it flips, flops, rotates around as if its not water but something a bit more sticky. See how everything just floats instead of any torque? Any ideas? Cheers!
10. ## Flip Narrow Band Particles Hitting Underside Small Scale

Hello, I have set up a simple narrow band flip tank and am dropping a small object (cosmetics bottle) into the tank. The issue im having is on the first frame that the object collides with the fluid it shoots a bunch of random particles out that escape from the narrow band and then re-collide with the underside of the fluid and cause ripples on the surface that I dont want to create. The RDB sim is running at a time scale of 0.05 and gravity is the only force in the scene so its moving very slowly. The time scale for the flip solver is 0.1 to get some splash, but as you can see from the attached photos its not anything crazy. Can anyone suggest a way to either stop this from happening or kill these particles before they collide with the narrow band? Im not the most versed at flip so this may be a very quick fix Appreciate any thoughts or help with this!
11. ## Kinks in stretchy flip sim

Hi all! I've got a stretchy flip sim, which is for the most part working as I'd like. It's a fluid that is being pulled apart with stretchy bands being formed. However I'm finding that when the bands become too thin, they begin to kink in a strange way, like in the attached image. I suspect this is something to do with the high surface tension in the simulation. I've tried may different adjustments to the settings, including upping the particle count, and substeps, but without any luck, Any advice or steer in the right direction to resolve this would be hugely appreciated! David
12. ## Flip particle doesn't collide with other flip particles...

Hello Community, I am having a problem that the FLIP particle doesn't collide with other parts of the flip particle. I have a simple scene that has a tank and emitter in the air. I want to pour the liquid into the tank. I was expecting that is going to create some splashes but it will just going straight down to the bottom of the tank. Does anyone have any idea? Thank you in advance. Flip_Test_v03.hiplc
13. ## How do I control the particle seperation of 2 different fluids using the same flip object?

I'm currently working on a melting scene where I have a number of objects that need to melt into a combined puddle. The way Im currently doing this is by converting the objects to points, giving them their attributes for density and viscosity before theyre taken into dops to run through a flip solver. From my testing and limited understanding, I believe its not possible to have the fluids as seperate flip objects because I couldnt get them to properly interract with eachother in the sim. Now for values which have attributes in the flip solver its no problem to assign these per melting object but what I want to be able to control is the particle seperation for each. I can change the point seperation in the pointsfromvolume node, and link this to voxel size in my vdb from particles node in my meshing process, but how would I also link this per object in my flip_object node in dops? cheers
14. ## how to slowly stop emitting particles from object for flip!?

Hey! Imagine you are slowly closing the water tap. then the water will decrease slowly. right !!!.. with reducing its thickness. That is what i am looking for. Animating the activation key on the "volume source node" would stops, right way. but i don't want that. Even animating the particle separation is killing the details of the shape. i want it to slowly stops with some kinda details. should i animate the scale of the object (which emits particle) or is there any other way to slow the emitting region or something. any one can help me please!? thanks in advance
15. ## The fluid inside the bubbles how to properly adjust the materials in the mantra?

Good evening everyone! I learned some lessons and trained at home in Houdini, and tried to make realistic fluids together in vials for honey and chocolate, other types. I looked at pictures on the Internet and carefully studied how to create bubbles, and tried to make mantra materials. but it’s not like photographs of real honey bubbles. I uploaded - a rendering image and a project HIP. Help me how to create materials correctly? hdri.rar honey_colorls.hipnc
16. ## Flip sim flows trough collider

Hello Everyone! I am learning fluid simulations, and I have no idea why my particles flows trough the container. Maybe there are problems with the voxel size (vdbfrompolygons),or something is missing in the flipobject or in the solver? Could you please gave me some advice? Thank you for your help in advance!! 2020-04-14_v003.hipnc
17. ## In POP-Fluid, where can I apply noise to the viscosity?

Hello; In Houdini 16.5, I would like to add "viscosity" to a "Particle Fluid" simulation using a noise pattern, so in DOP I add a "POP-VOP" node (and AANoise in it ... ) after "Source Volume" which doesn't work. Where could I apply noise to the viscosity? Thanks for helping. Viscosity.hip
18. ## beach tank flip streaks

Hello! I'm having a problem when doing a beachtank. The motion of the waves looks good, but when the waves are retracting, there is a bunch of points that stops moving and forms a line that does not move. I've tried to increase the substeps of the DOP, but it didn't make a difference. My beach has a slope and it doesn't look like there is something else affecting it. Any help is appreciated, thanks!
19. ## Newbie struggling with wet maps on a beach tank

Hi... I have created a scene where ocean waves hit sand... Used the beach tank from Oceans tool shelf. In order to accomplish the wetmap on sand I have taken the following steps: 1) Cached out the fluid surface cache 2) Scattered points on the fluid surface and added @wetness = 1 attribute 3) Used group bounding box delete to only keep the points near the shore 4) Scattered points on the sand surface and added @wetness = 0 attribute, points inherit UVs from sand - note sand geo has UV textures applied on the diffuse and other channels. Y axis projection, scale = 15, 15, 15. Resolution 8K. 5) Created another geo and object merged from #2 and #4 6) In that geo created a solver that: - copies wetness attribute from previous frame of the sand-scattered points onto current frame - uses attribute transfer to transfer wetness from fluid particles 7) This works great... so I have points scattered on the fluid particles transfering wetness attribute to points scattered on the sand particles. But how do I convert that into an animated map that I can load onto the original sand object? How do I blend that map with existing textures? - I have tried to follow a tutorial where author created a vopcop2 generator in img context and created the flow in VOP as per attached file - But this is not really working well... (a) its very slow (b) I get a small something that doesn't seem to animate or read the exact details of the points. Is there a better way do do this? One that might actually work? Huge thanks.
20. ## FLIP Retiming jitter

Hi everyone, I'm trying to retime a flip sim, but the retime node is creating a jittering when interpolating frames. Would this have anything to do with particle ids or num of particles changing between frames? and this is mucking up the interpolation? Thanks in advance, David RetimeJitter.hiplc
21. ## Trouble transfering UV's of a flip fluid

Hey all, Ive been following a tutorial on how to transfer the UV's to simulated flip fluid and all was going well untill I added a remesh node to the transferred UV attribute which was supposed to smooth out the mesh to preserve the detail of the texture. Instead what has happened is that the UV's have gone from being seperate shells to having all their edges connected together. There is already a vertex split in the node graph which fixed the issue before I added the remesh node. Any help would be greatly appreciated, I've provided the scene file - thanks a bunch Melting_Example_v001.hiplc
22. ## MIX FLUIDS WITH DIFFERENT SHADING

Hi all I'm stuck with this. What is the best way to mix two fluids that have different parameters (i.e viscosity)? Both will have different shadings. Any ideas. Attached reference scene. Thank you very much to all Mix_flips_RnD.hipnc
23. ## Boat explosion

Hey guys, Here's a new project I'm working on as I have some free time. The boat is a free model from cadnav. The main rbd sim with instanced debris is there : https://streamable.com/pcayf I used the new rbd deform pieces for the mesh (which is pretty useful) and I'm looking to add some noise and more details to the edges later. I've made the explosions (but infortunately I have only 119 frames because it crashed, I may resimulate the explosions 1 by 1 instead of the 4 in a row) : https://streamable.com/sjcje I've also made a quick low res render to see how the ocean and the explosions behaved all together with a lil bit of comp (to match my background) : https://streamable.com/1sduw Now I need to add sparks, smoke trails, and flip white water, and maybe additionnal splashes, refine the ocean.. Cheers and happy confinement !
24. ## Flip Source From Points

Hi everyone I was playing with the flip source node and I am wonderig : is there a way to create a flip source from points, instead of from geometry ? For exemple now I want to create a flip collider from a point simulation, if I want to use the cool flip source node I have to create a vdb from particles + convert vdb to mesh + flip source, I guess there would be a more efficient way ? Have a good day, thank you for your time
25. ## flip fluid Water Tornado (inverse whirlpool) help

Hey wizards! So I'm working on a project and I'm tasked with doing an inverse whirlpool. I've tried several techniques like curve force and axis force but they become unstable and don't give the desired effect I need. I'm currently using pop particles to affect the flip and it works, but it continues to grow then it becomes unstable. I'm trying to recreate the effect in the pokemon video but I need it to run for a long time without being unstable. What would be my approach to achieving this effect? Here is my hip file that I'm working on, maybe someone can notice if I'm doing something wrong lol water swirl.flv smalltornado_unstable.mov smalltornado_unstable2.mov watertesting_forum.hiplc
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