7 replies to this topic

[anupamd]

Just curious if there is a way to control simulation attributes per point?
For example, if I have a fluid flowing over a surface, and want the friction coefficient of the surface to vary across the surface using a noise pattern..so that the fluid breaks up in an organic way as it flows down. (this would be a nice way to get good detail without using complex collisions)

Perhaps another way to do it is to vary the separation scale per fluid particle, to get a sort of per-particle viscosity.  

Or.. perhaps if all we are doing is modifying the divergence field, some way to modify the existing divergence field to get the desired result?

Either way, these are great ideas however I do not see a way to get at the data and manipulate it. I dont see this data existing as a scalar/vector field anywhere.

Any help would be great thanks!

- Anupam

Edited by anupamd, 01 August 2011 - 12:45 PM.

[lukeiamyourfather]

I realize you are asking these questions about Houdini but RealFlow does all of those things out of the box without modifications to the solvers. I've found the SPH and FLIP tools in Houdini to be good for small/quick effects but for larger or more complex fluid simulations RealFlow is much more intuitive, featured and faster. Especially when Houdini is calculating SDF for animated objects with many substeps, the performance is so bad it becomes pretty much unusable. Creating non-Newtonian fluids in Houdini could be pretty ugly as I don't think the solvers have that already integrated. I don't have the knowledge to suggest how to do it in Houdini but I'll be watching as I'm curious as well. Good luck with the shot.

[anupamd]

well the sim Im doing is fairly simple and it can be low res (the low rez fluids will be driving some other effects, the the fluids themselves wont be visible).
I just figure with all that houdini can do, there has got to be a way to get a little more deeper control.

Any fluids expers out there.. Bunker, PClaes? =)

ps: I dont think I can avoid not using realflow for much longer though, so I'm going to start messing with it. The RF to houdini dop is pretty solid from what I hear and imports just about every attibute.

[Stalkerx777]

anupamd, on 01 August 2011 - 12:27 PM, said:

Just curious if there is a way to control simulation attributes per point?
For example, if I have a fluid flowing over a surface, and want the friction coefficient of the surface to vary across the surface using a noise pattern..

Hi.It can be done very easily in houdini. Here is an example.
I paint friction with a paint SOP here, but you can do whatever you want to set "friction" attribute. You can use texture,vops or any procedural approach.Same with most of the other attributes(mass,bounce,velocity,stiffness...etc.)
Good Luck.
 paint_friction.hip   203.07K   179 downloads

[lukeiamyourfather]

Stalkerx777, on 01 August 2011 - 11:34 PM, said:

Hi.It can be done very easily in houdini. Here is an example.
I paint friction with a paint SOP here, but you can do whatever you want to set "friction" attribute. You can use texture,vops or any procedural approach.Same with most of the other attributes(mass,bounce,velocity,stiffness...etc.)
Good Luck.
paint_friction.hip

That's a great example for the object attributes. I wasn't aware they could be passed in an attribute like that. Any thoughts on non-Newtonian fluids in Houdini?

[bunker]

@lukeiamyourfather have a look at this thread :

http://forums.odforc...l__cake__st__36

I hope you get some discount on your next Realflow license  

lukeiamyourfather, on 02 August 2011 - 11:15 AM, said:

That's a great example for the object attributes. I wasn't aware they could be passed in an attribute like that. Any thoughts on non-Newtonian fluids in Houdini?

Edited by bunker, 03 August 2011 - 01:46 AM.

[anupamd]

AS usual, someone posts a hip file that totally opens new doors for me. Love love love this forum. Thanks! Im digging further into this right now, i'll post some tests if I produce anything interesting.

bunker, on 03 August 2011 - 01:45 AM, said:

@lukeiamyourfather have a look at this thread :

http://forums.odforc...l__cake__st__36

I hope you get some discount on your next Realflow license  

[lukeiamyourfather]

bunker, on 03 August 2011 - 01:45 AM, said:

@lukeiamyourfather have a look at this thread :

http://forums.odforc...l__cake__st__36

I hope you get some discount on your next Realflow license  

I don't see anything in that thread about non-Newtonian fluids. Looks like a discussion about high viscosity fluids to me which are not the same thing. Is there a specific post I missed? I assume you're being sarcastic about the RealFlow discount in which case the snide remark was unnecessary and unprofessional. What's wrong with choosing the right tool for the job? Go browse the RealFlow forum, where appropriate I recommend Houdini and other tools (if I think they are the right tool for the job).