LouisXIV Posted July 7, 2016 Share Posted July 7, 2016 (edited) hi, I cant get my fluid to smoothly flow down a -.5 rotated flat surface. After a few frames it will flow down a bump and get faster. The fluid runs smoothly on the same surface without the rotation. My guess its a problem coming from the rotation and its voxel interpretation. I really pushed the collision resolution and tried different collision methods(static object/ source volume), still the same problem. I'm using Houdini 13.0.7 but also checked the file with apprentice 15.5, still the same problem. Has someone faced the same problem? I really would appreciate every help, thanks in advance Martin .hip is attached fluid_collision_1.hip Edited July 7, 2016 by LouisXIV Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 7, 2016 Share Posted July 7, 2016 I took a look at your file and it looks like you were changing a bunch of things from the default values on the solver. So I took what values I saw and converted them back to default, it wasn't until I put the surface extrapolation back to 0.5 that your sim started behaving the way it should. Be careful changing random things in the solver like this because you could go deep into the rabbit hole and then you won't know what is influencing what anymore. Attached is the modified file so you can see where I left off. Also, the max axis on your static object was 350?? That is crazy for just a box and actually for alot of things. fluid_collision_1_RB.hip Quote Link to comment Share on other sites More sharing options...
Atom Posted July 7, 2016 Share Posted July 7, 2016 (edited) In flip, collision resolution is tied directly to particle separation. So there is no need to excessively increase the collision volume for the static object. Instead reduce the particle separation. Try turning on the Collision guide under the FLIP object to see the "true" collision mesh, as the solver will see it. NOT the static object visualization. I have set the flip collision guide to a green color so it would stand out. Notice the gaps in the green that allow the particles to fall through at particle separation 0.03? ap_fluid_collision_1.hiplc Edited July 7, 2016 by Atom Quote Link to comment Share on other sites More sharing options...
LouisXIV Posted July 7, 2016 Author Share Posted July 7, 2016 (edited) thanks for looking at my file. i changed the surface extrapolation because i got this edge below my sphere(pic1) but your absolutly right the default value works mutch better for the sim. I took your file and upresed the particle seperation(fluid object) to 0.005 and now i get really weird collisons (pic2). ah and with the 350 on the static object i just wanted to get sure that the collision resolution is not the problem. I looked at the collision representation on the fluid object, this is what it looks like When i disable the rotation of the collision box, everything works fine... i attached the new file Thanks guys for the help!! fluid_collision_2.hip Edited July 7, 2016 by LouisXIV Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 7, 2016 Share Posted July 7, 2016 What kind of fluid are you going for here? Is it supposed to be viscous? Not sure what is going on with the line yet but, I can see what you were trying to do with the surface extrapolation now. Changing that back to .01 gets rid of the line somewhat but, I am unsure if that is the right way to go about it. Quote Link to comment Share on other sites More sharing options...
LouisXIV Posted July 7, 2016 Author Share Posted July 7, 2016 (edited) Yes its supposed to be a little viscous, like close up milk/blood running over the ground. the line is really strange, i mean its just a box. Somehow the slight rotation messes up the collision. Edited July 7, 2016 by LouisXIV Quote Link to comment Share on other sites More sharing options...
rbowden Posted July 8, 2016 Share Posted July 8, 2016 The line is strange but, it seems to have something to do with everything being center of the axis. For instance, if you make the box a bit bigger and move the emitter away, you wont see the line in the collision until it hits the center axis. This could be a bug and you should definitely report this. Quote Link to comment Share on other sites More sharing options...
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