Jump to content

Surface tension and viscosity


Pancho

Recommended Posts

Am I the only one who seems to experience flip fluid movement due to surface tension on high viscosity fluids? Viscosity is set to 100.000, object size about 5cm (0.05 units) and tension is set to 1.

The details disappear rather quickly and the surface gets smoother. THis shouldn't happen with such a high viscosity. Can I override the surface tension per particle, since the viscosity changes on a per particle basis? H16 here with the new surface tension in the solver.

 

Cheers
Tom

Link to comment
Share on other sites

Well, if you want to melt something in H16 and it turns into a liquid it shouldn't deform before changing from its solid state into a liquid one. The way to do this a.f.a.i.k. is to use high viscosity and then change it to something lower.

Link to comment
Share on other sites

Do you have a test file that shows this? Simple tests here don't show any movement with high viscosity and surface tension.

 

Surface tension attributes aren't in H16, you should be able to build it though with a GasToParticle and a new field IIRC.

Link to comment
Share on other sites

16 hours ago, marty said:

Do you have a test file that shows this? Simple tests here don't show any movement with high viscosity and surface tension.

 

Surface tension attributes aren't in H16, you should be able to build it though with a GasToParticle and a new field IIRC.

Their are new surface tension control and attributes in H16 within the flip solver itself, how accurate etc it works i dont know but pretty sure it is their 

Link to comment
Share on other sites

11 hours ago, chrisdunham95 said:

Their are new surface tension control and attributes in H16 within the flip solver itself, how accurate etc it works i dont know but pretty sure it is their 

Hmmm - not sure why you think there is an attribute for surface tension, because.. ta da.. there isn't!

Link to comment
Share on other sites

14 minutes ago, marty said:

Hmmm - not sure why you think there is an attribute for surface tension, because.. ta da.. there isn't!

You can control the pressure jump per particle with a scalar field as a factor for the surface-pressure field. Attached is a very raw example of it.

I hope that helps!

Cheers

Alejandro

pp_st.hip

  • Like 2
Link to comment
Share on other sites

3 hours ago, chrisdunham95 said:

 this is what i am referring too; 

right - so how do you define that control to have more surface tension in low viscosity vs high viscosity areas?

Link to comment
Share on other sites

7 hours ago, chrisdunham95 said:

Im not sure but my point was their is a surface tension attribute in the new h16 :)

That Surface Tension control is a 'parameter' - totally different to an 'attribute' in Houdini.

Link to comment
Share on other sites

  • 2 weeks later...
On 22/06/2017 at 11:54 PM, Dave Stewart said:

Pazuzu's file, slightly modified, would let you drive the surface tension field values based on a point viscosity attribute or whatever. Makes for some interesting shaping by the end! :)

See attached modded file...

--Dave

pp_st_ds.hip

That's super awesome. Thanks Dave and lord Pazuzu... :D you guys are TOP

Link to comment
Share on other sites

On 6/23/2017 at 9:27 PM, marty said:

That Surface Tension control is a 'parameter' - totally different to an 'attribute' in Houdini.

Well, yes and no. It's a field in the flip solver so you can vary it by voxel, like Dave/Pazuzu did above. Conceptually I would regard it to be closer to an attribute than a parameter, even though you would need a spoonful of extra noodle soup to source it from a point attribute.

The name is surfacepressure not surfacetension, but don't let it fool ya ;)

Link to comment
Share on other sites

If you want to find even more details of the amazing surfacepressure implementation in the FLIP solver, look at the second edition of the "Fluid Simulation For Computer Graphics" book!! Is amazing!!! :) 

Cheers!

Alejandro

Edited by Pazuzu
  • Like 3
Link to comment
Share on other sites

Here's another version using PopVop/GasFieldVop instead of wrangles... hope it helps clarify the process! Set this up *very* quickly so let me know if I missed anything. Should be able to drive the surfacepressure field directly from the viscosity field, but the values would probably need adjusting in the 'fit' node.

--Dave

pp_st_ds_PopVOPs.hiplc

Link to comment
Share on other sites

8 hours ago, eetu said:

 Conceptually I would regard it to be closer to an attribute than a parameter, even though you would need a spoonful of extra noodle soup to source it from a point attribute.

it's simply a matter of the degree of generalisations and context here.. e.g. hey you call that a number! it actually an element of a field, a scalar, a coordinate, a component, a matrix and a vector. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...