Changing fluid emitter scale

[BYNUMDAV]

Hello,

I am modifying the faucet scene for VR and have a problem with the scale of the little fluid spheres that make up the simulation. When I view the scene in VR its really huge, so I am wanting to scale it all down. When I attempt to scale down the radius of the Obi particle renderer, the whole simulation fluid simulation does not look right, as if there is space between the particles. The default scale is set to 1.5, and anything below 1 looks terrible. Any help would be greatly appreciated.

Thanks

[josemendez]

Hello,

I am modifying the faucet scene for VR and have a problem with the scale of the little fluid spheres that make up the simulation. When I view the scene in VR its really huge, so I am wanting to scale it all down. When I attempt to scale down the radius of the Obi particle renderer, the whole simulation fluid simulation does not look right, as if there is space between the particles. The default scale is set to 1.5, and anything below 1 looks terrible. Any help would be greatly appreciated.

Thanks

Changing the radius of the particle renderer only changes the size of the rendered particles, not the resolution of the fluid. This is used to control the look of the rendered fluid surface, but does not affect the simulation at all.

To change the fluid resolution (i.e the physical size of particles), set the fluid material "resolution" value. High resolution values yield smaller particles, low resolution values result in larger particles. All related quantities (particle mass, kernel radius, etc) are automatically set based on resolution. Then, the renderer radius is just a multiplier of the actual size set by the resolution, and only affects rendering. See the docs:
http://obi.virtualmethodstudio.com/tutor...rials.html

[BYNUMDAV]

Changing the radius of the particle renderer only changes the size of the rendered particles, not the resolution of the fluid. This is used to control the look of the rendered fluid surface, but does not affect the simulation at all.

To change the fluid resolution (i.e the physical size of particles), set the fluid material "resolution" value. High resolution values yield smaller particles, low resolution values result in larger particles. All related quantities (particle mass, kernel radius, etc) are automatically set based on resolution. Then, the renderer radius is just a multiplier of the actual size set by the resolution, and only affects rendering. See the docs:
http://obi.virtualmethodstudio.com/tutor...rials.html

Thanks for the reply. I have changed the scale of the particles as you suggested, but when I run the simulation the liquid just explodes everywhere. I have changed a sorts of variables and have been fiddling far too long just to get a ballpark accurate simulation in correct scale with no success. Do you have any examples that are the right size? Having something that works to reference would help a lot.

What I am looking to accomplish is to have an enclosed orb (about the size of a fist) half filled with fluid that can just slosh around. I don't need it emitted in a flow or burst, just need it to exist there in the orb when the scene starts. Do you have a good idea as to how I can accomplish this?

Thanks

[josemendez]

Thanks for the reply. I have changed the scale of the particles as you suggested, but when I run the simulation the liquid just explodes everywhere. I have changed a sorts of variables and have been fiddling far too long just to get a ballpark accurate simulation in correct scale with no success. Do you have any examples that are the right size? Having something that works to reference would help a lot.

What I am looking to accomplish is to have an enclosed orb (about the size of a fist) half filled with fluid that can just slosh around. I don't need it emitted in a flow or burst, just need it to exist there in the orb when the scene starts. Do you have a good idea as to how I can accomplish this?

Thanks

Hi!

If the fluid is exploding, that means either your viscosity or your surface tension are too high for the mass of your particles (the docs state that they can cause the simulation to be unstable if too high). Reduce them to zero, and start cranking them up slowly till you like the behavior.

Alternatively, instead of changing the simulation resolution you could perform the simulation in local space instead of world space (check "local space simulation" in the solver, then parent the emitter under the solver), then just scale the solver to scale the whole simulation to whatever size you need. This however has the drawbacks associated with local space: moving the solver around won't affect the movement of your particles.

[Kalidor]

Would be nice if you can make a sample scene.
I also want to have a nice looking liquid in VR.
Especially the spheric shape of the particles is visible.
If there is any solution to hide the shape to some degree...

[josemendez]

Would be nice if you can make a sample scene.
I also want to have a nice looking liquid in VR.
Especially the spheric shape of the particles is visible.
If there is any solution to hide the shape to some degree...

Hi Kalidor,

Particles can only be spherical. You can increase their size a bit using the ParticleRenderer's "radius scale", and at the same time increase the FluidRenderer "thickness cutoff". This will smooth the shape out a bit, blending particles together a bit more.

What do you need the sample scene for? (what do you want it to feature exactly?)

[Kalidor]

I want to fill a barrel with fluid.
There should be the possibility, if the fill level is at it's maximum, that the fluid can overflow.
Expecially when the fluid is on the ground it looks like there are a bunch of bubbles in it.
(Similar to your "FaucetAndBucket" scene)

[josemendez]

I want to fill a barrel with fluid.
There should be the possibility, if the fill level is at it's maximum, that the fluid can overflow.
Expecially when the fluid is on the ground it looks like there are a bunch of bubbles in it.
(Similar to your "FaucetAndBucket" scene)

Hi Kalidor,

The setup is pretty much identical to that in the FaucetAndBucket scene, with the exception that you swap the bucket mesh with a barrel mesh. Also you need to tweak the fluid parameters to your liking. The fluid will automatically overflow when the barrel is full.

Regarding the bubbles, you'd need to either write your own fluid shader for that, or advect regular particles trough the fluid, similar to what is done in the FluidFoam scene.

cheers,