Why are these fluids so graining when blending

[stelees]

Hi there,

Per the attached pic I am trying to blend two liquids together but the blend is really really grainy.
Cell size is .184cm, 14 substeps RGB Diffusion is .8, Surface tension is .15 and the rest is as is.

Looking at vids on youtube and such when you see liquids poured into together they don't basically end up looking like this.

Any ideas on what I should be looking at to make this less grainy?

[georgi.zhekov]

Hey,

If you're using the Grid texture to blend the two materials you can try to set the Sampler in the Grid Tex options to Spherical. If this does not solve it you can try and use the Particle Texture instead of the Grid one (just make sure you have the particle rgb channel exported in the Output rollout)

If you're using the Particle texture you will need to duplicate your simulator (hide it and make it non-renderable) and then read the particle data from the duplicate - otherwise a circular reference would occur.

Then to get a smooth result you can play around with the Particle area radius. Note that larger value will render slower so start small and increase it gradually.

Cheers!

[stelees]

Using Grid so will have a crack at that change. cheers

[JuhaHo]

I have somewhat similar project at the moment. However the transparency of the liquids are different. The poured liquid should be almost transparent, but the liquid on the container should be almost opaque. What would be the best practice for visualizing that.

[georgi.zhekov]

I have somewhat similar project at the moment. However the transparency of the liquids are different. The poured liquid should be almost transparent, but the liquid on the container should be almost opaque. What would be the best practice for visualizing that.

Hey,

This is quite tricky setup up as the V-Ray Blend material is not designed to work in volumetric mode and it's surface based. So if you need to see how the two liquids mix in depth - it won't look good. The same applies to the fog color of the V-Ray material.
This is why you will need to use two simulators to make this work.

1. The liquid source emits black RGB channel, while the default RGB for the simulator is white.
2. Create a second Phoenix Fire/Smoke Simulator and set it to render in Volumetric mode and render only the smoke, this means the fire is disabled, simple red color, and texture based opacity.
3. In the texture slot for the smoke opacity for Fire/Smoke simulator use a Phoenix Grid Texture and select the Liquid simulator in it, set the RGB channel to be used.
3. Set the liquid simulator to be a cutter geometry of the fire/smoke sim.
4. Assign simple water material to the liquid simulator.
5. Place the fire/smoke simulator exactly to overlap the liquid one. This is really important, otherwise the liquids will be mismatched.

Here is a sample scene how this works.

[JuhaHo]

Thanks Georgi,

I simulated and rendered the scene. I don't know if it's what I'm looking for, but definitely a good solution. In my own scene I used two emitters with different vertex colors. One emitter fills the system and the other is for pouring the liquid chemical into simulation. I was wondering if there's a way to use particle grid RGB as a refraction map, but I don't know how to implement that correctly to material refraction channel.

At the moment I'm thinking to try a vertical gradient map with animated noise and cylindrical mapping. I might even use the same gradient map in reflection channel too.

Once that looks good, I think there's the toughest puzzle remaining. Along with liquid pouring there's poured particles too, that are melted to liquid. I don't even try to melt down the particles - just fade them out where the system turns to opaque. For particles, I tested the Phoenix PFlow operator. It worked as expected, which is not good in my case. I want the particles to be inside the liquid - not on the surface of it. Particles being on surface means, that some particles will render outside of the container, which isn't exactly what I'm looking for.

[georgi.zhekov]

I was wondering if there's a way to use particle grid RGB as a refraction map, but I don't know how to implement that correctly to material refraction channel.

This won't look good as the V-Ray material fog color will work only on the surface but not it depth, this is why I suggested the setup from above.

For the particles may be you can use a cutter geometry in the Particle Shader? You can make a dummy non-renderable geometry and use it a a cutter for the particles, this way you can render only the particles inside (or outside) the dummy geometry.

[JuhaHo]

OK, thanks.

I hesitate using cutter object, because I think, it might have conflict with the V-Ray clipper, i'm using to open the container during rendering. I think one thing to try is to bake the particle system into meshes and scale that scene down a bit. Then I would get also benefit tho random materials to particles.

Anyway Phoenix seem to have lost the license during ongoing simulation and the simulation has stopped. Most probably because of the very poor internet connections in our area. The chaos license server for Phoenix FD cannot be contacted at the moment, but the ongoing V-Ray renderings are going fine. I need to investigate this.

[georgi.zhekov]

There were some issues with the licensing services, but now it should all be good. Let us know if you still have some issues.

Thanks!