whitewater birth control

[gramx]

Hi

I have been playing around with the new whitewater solver in 12.5 and was wondering if there was a way to control the birth amount of spray/foam/bubbles individually. You currently have a birth rate in the whitwater_replicate node that controls all three outputs together. You can also adjust the emission from curvature/vorticity/acceleration within whitewatersource, however this also affects all three outputs together. What I would like to do is increase the amount of spray particles without affecting the foam and bubbles, or maybe decrease the amount of bubbles without affecting the other two. Is this possible?

Thanks

Gram

Edited April 21, 2013 by gramx

[Skybar]

You could just create 3 whitewater-systems, and then turn off spray/foam/bubbles respectively so that each "system" (don't know what to call it) only handles one of them. You could then also shade them differently, sim/render them seperately and so on. I don't know if it is the "right" way to do it, but it has worked for me.

[gramx]

Thanks for the reply. Yes I have been doing this also it works well for the bubble pass. however the spray pass turns into foam as it impacts with the water which I think you loose if you just sim spray. What I am trying to do is increase the amount of spray without increasing the amount of foam that is created from the surface but still keep any foam that is created from the spray impacting the surface. does that make sense? So what I really need is a seperate birth multiplyer for the spray pass!

cheers

g

[johner]

Thanks for the reply. Yes I have been doing this also it works well for the bubble pass. however the spray pass turns into foam as it impacts with the water which I think you loose if you just sim spray. What I am trying to do is increase the amount of spray without increasing the amount of foam that is created from the surface but still keep any foam that is created from the spray impacting the surface. does that make sense? So what I really need is a seperate birth multiplyer for the spray pass!

Generally I agree the best approach is to augment the original whitewater pass (foam/bubbles only or all types) with another sim that has just Spray enabled. You do lose the spray causing foam on the surface, but it's usually not noticeable, especially if your spray particles lifetime isn't very long anyway.

There's not a multiplier on any of the particle types, primarily because the particles aren't classified as the various particle types until after they are emitted. That said, there are things you can do to increase the ratio of spray particles.

In WhitewaterSource, you can decrease the emission probability of any vorticity and acceleration emitters, which tend to be deeper in the fluid, and increase the curvature weighting, which tends to be near the surface. Or even use two WhitewaterSources, with one specifically tuned to create high probability emitters mostly at the surface, then merge the two outputs before sending them into whitewater. If you do this, be sure to delete the surface and vel volumes from the second Whitewater Source output. Turning on the emission visualization can be helpful to identify high-probability emitters.

Another setting that creates more spray is the Center Z-parameter on the Shape tab of the POP Replicate. Increasing this moves the replicated particles out along the velocity vector, meaning more of the particles will escape the fluid and become spray.

You can plug a PointReplicate SOP into the output of the Whitewater Source to preview all these emission changes, as POPReplicate is mostly just an embedded PointReplicate.

Edited April 24, 2013 by johner

[gramx]

Thanks john!

Some very useful tips! I will definitely have a play round with the whitewater source and the Center Z-parameter.

Thanks Again.

gram

[ikarus]

You can always add spray points that are in/near the surface to the emitter of your foam/churn/etc sim.

[mingxing]

Hi gramx

I'm Studying Houdin 12.5,using flip tank and white water

I watch your work on vimeo .it's amazing ,very nice .I have some queston:how you make the spray/foam/bubbles moving so fast ,flying so high,Add a velocity field or curlnoise field around the object or something other.....

would you like share you hip files?Just the under below,I will very appreciate!!

http://vimeo.com/64140693 (At time 00:18)

[Sty]

*

Maybe ask for share personal files is too much, but some highlights on these scenes would be so cool

[gramx]

Hi

I used a sphere at the rear of the jetski and turned it into a pump object to add velocity and curl noise to the Solver. Here is a simple setup:- https://dl.dropboxusercontent.com/u/73974952/jet_emitter.hipnc

Hope it helps

Graham

[sheyoystudio]

Hi

I used a sphere at the rear of the jetski and turned it into a pump object to add velocity and curl noise to the Solver. Here is a simple setup:- https://dl.dropboxusercontent.com/u/73974952/jet_emitter.hipnc

Hope it helps

Graham

 

Thank you Gramx!!

Edited April 5, 2015 by sheyoystudio