Grid Fluids and vorticity

adom86
Posts: 22
Joined: Wed Aug 04, 2010 9:23 pm

Grid Fluids and vorticity

Postby adom86 » Thu Oct 21, 2010 9:10 am

Hey

I hope I am wrong but I am assuming that Grid fluids cant produce a vortiity channel like standard emitters?


User avatar
tmdag
Posts: 1023
Joined: Thu Jun 28, 2007 2:22 pm
Location: New Zealand
Contact:

Grid Fluids and vorticity

Postby tmdag » Thu Oct 21, 2010 9:26 am

They cannot and they can :)
Vorticity is just a rotation of particles.. in grid You don't have a particles so there is no place to add vorticity on.

In grid domain you have velocity vector field that on each voxel you have velocity vector that advect your fluid geometry and makes it spin/move etc.

I would have to check but maybe with python You could advect velocity on scattered particles over grid and then compute vorticity out of it. But still this would be only a vorticity of particles.


what you want to achieve?
"Do not feed the trolls"
Albert 'tmdag' Szostkiewicz
FX Technical Director
Weta Digital

adom86
Posts: 22
Joined: Wed Aug 04, 2010 9:23 pm

Grid Fluids and vorticity

Postby adom86 » Thu Oct 21, 2010 9:29 am

tmdag wrote: They cannot and they can :)
Vorticity is just a rotation of particles.. in grid You don't have a particles so there is no place to add vorticity on.

In grid domain you have velocity vector field that on each voxel you have velocity vector that advect your fluid geometry and makes it spin/move etc.


what you want to achieve?

Thanks for the reply. I am wanting to bring the bin sequence into max and therefore Krakatoa and map the colour based upon vorticity but I seem to be hitting a brick wall with the setup. I have just simulated a test using standard particles and it appears to be working I believe.

Cheers

User avatar
tmdag
Posts: 1023
Joined: Thu Jun 28, 2007 2:22 pm
Location: New Zealand
Contact:

Grid Fluids and vorticity

Postby tmdag » Thu Oct 21, 2010 9:34 am

so again - even with vorticity, how you would like to render grid fluid (that you would have as a standard mesh) with Krakatoa ?

afaik Krakatoa renders particles only


As I said - You can advect particles and then compute vorticity.
"Do not feed the trolls"
Albert 'tmdag' Szostkiewicz
FX Technical Director
Weta Digital

adom86
Posts: 22
Joined: Wed Aug 04, 2010 9:23 pm

Grid Fluids and vorticity

Postby adom86 » Thu Oct 21, 2010 9:38 am

tmdag wrote: so again - even with vorticity, how you would like to render grid fluid (that you would have as a standard mesh) with Krakatoa ?

afaik Krakatoa renders particles only

Yes I find that rendering the fluid without a mesh but by using krakatoa and voxel shading using a colour map by the vorticity channel looks a lot more fluid and realistic but the problem I am having is that when using my Grid particles (about 9 million) they dont appear to have a vorticity channel within the bin files which is a shame

User avatar
tmdag
Posts: 1023
Joined: Thu Jun 28, 2007 2:22 pm
Location: New Zealand
Contact:

Grid Fluids and vorticity

Postby tmdag » Thu Oct 21, 2010 11:45 am

you can always compute vorticity on every emitter by script (automatically added with realflow in shelf)
"Do not feed the trolls"
Albert 'tmdag' Szostkiewicz
FX Technical Director
Weta Digital

adom86
Posts: 22
Joined: Wed Aug 04, 2010 9:23 pm

Grid Fluids and vorticity

Postby adom86 » Thu Oct 21, 2010 11:49 am

tmdag wrote: you can always compute vorticity on every emitter by script (automatically added with realflow in shelf)

Ahhh I did not know this, any idea or brief idea on how to go about doing this. Im not very good at scripting yet ... appreciate your help, you are the only one who has responded :)

I found the option, gonna give it ago!

*edit* dont think it works with grid fluids as it just says

>[21/October/2010 13:07:41] - Executing script... (Press ESC to abort)
>[21/October/2010 13:07:41] - Done...

User avatar
tmdag
Posts: 1023
Joined: Thu Jun 28, 2007 2:22 pm
Location: New Zealand
Contact:

Grid Fluids and vorticity

Postby tmdag » Thu Oct 21, 2010 1:05 pm

because it works only on particles and u wrote "using my Grid particles (about 9 million)" so use it on those particles.
"Do not feed the trolls"
Albert 'tmdag' Szostkiewicz
FX Technical Director
Weta Digital

adom86
Posts: 22
Joined: Wed Aug 04, 2010 9:23 pm

Grid Fluids and vorticity

Postby adom86 » Thu Oct 21, 2010 1:36 pm

Well I meant I tried it on the particles or I think I did. I may not be doing it correctly but I tried selecting the particles and running the compute vorticity and it doesnt do anything.

*edit* ah well after a few tests it would appear you can compute the vorticity after the initial sim on standard particles and splash particles but not grid particles. Strange :(

User avatar
tmdag
Posts: 1023
Joined: Thu Jun 28, 2007 2:22 pm
Location: New Zealand
Contact:

Grid Fluids and vorticity

Postby tmdag » Thu Oct 21, 2010 1:57 pm

maybe I don't understand your approach - what are grid particles?
"Do not feed the trolls"
Albert 'tmdag' Szostkiewicz
FX Technical Director
Weta Digital


Return to “RF5: Fluid simulation”

Who is online

Users browsing this forum: Bing [Bot] and 0 guests