FLIP fluid flow on surface with painted flow control question

[ford77]

Hi,

I need to create an ink like effect where a liquid is poured on a surface and it`s flowing down slowly.

Can anybody tell me how can I control the parts of the surface where the fluid can flow?

I`ll have a geo and I need to be able to control where the ink can flow down on it

with painting on the surface.

The only thing I could come up with so far is to attribtransfer the color attributes

from the surface on the flip fluid particles in a sop solver and use tha to set friction to a high value on

all areas except where the fluid should flow, but it only slows down the particles

very much and they create a thick layer there instead of simple moving to low friction

areas and flowing down the surface.

I`m thinking about creating a divergence/pressure field from the surface

with point clouds filtering the painted color/attribute, but I don`t know how

to wire it together in Houdini.

Any ideas, help and explanation appreciated.

Thank you!

[gui]

why you just extrude out the parts you don´t wanna the liquid to be? This way you will create a path for the liquid to flow.

[tshnrk]

Maybe scatter points in the black area and use them as attractors inside a pop solver?

[Nerox]

You could also build a custum velocity field in SOPs and use it to push the fluid away from parts where you don't want it to be. You could even push them along the stream at the same time, or in the opposite direction.

In SOPs you can build your velocity volume how ever you want, make sure it matches the DOP voxel size, which is 2x the particle separation. In DOPs use a SOP Vector Field which goes into the object stream, point this to your sops velocity volumes (vel.x, vel.y, vel.z) and toggle 'use SOPs dimensions'. Make sure its underneath the FLIP object and above the solver. Then connect a Gas Calculate to the velocity input of the solver and set dest field to vel and source field to the name you've defined on the Sop Vector Field (data name). Set the calculation to add. Now you can use the 'source pre-mult' on the gas calculate to control the influence.

Good luck! :-)

[ford77]

Thanks for the replies.

gui:

The problem with extrusion is that it`s complicated and needs tweaking when the geo is concave and complicated. And the particles will collide and be thicker instead of just flowing in a nice path smoothly. Anyway, I tried this first, it needs very detailed geo to create the hills and valleys where the fluid can flow. I leave it as a solution when nothing else works.

tshnrk:

I`ll try the attractors, but i`m not sure about it. If it attrtacts, ho do I make sure the fluid is still coming down along the surface, avoiding repelling areas? I mean attractors attract from all direction and then it`s done, but I need them to be attractec away from certain areas but be unaffected otherwise. I guess it`s more complicated.

Nerox:

I don`t completely understand this method, but I guess instead of tweaking the vel field with a gas calculate, I could just put it in a field force if I had a vector field anyway.

[fayal]

hi,

may be this file can help:)

fluid flow color.hipnc

Edited October 29, 2012 by fayal