Non-Newtonian liquid

[JuhaHo]

I was trying to find information about non-Newtonian liquid in PhoenixFD context. Would it be possible to include a preset, so I could try studying it? AI told me that most common non-Newtonian liquid would be Slurry. I don't even know what that is, but would be interesting to know PhoenixFD settings for creating one. Any help available here?

[zdravko_pavlov1]

Hello,
Have you tried the example scene available on the docs page?
https://docs.chaos.com/display/PHX4MAX/Liquid+Dynamics

There's also an explanation and an example video.

[JuhaHo]

Thanks,

I've been watching those earlier. However, I was thinking if there would be sample based on known substance. I have read, that blood is non-newtonian substance, but I'd rather would not use that. Then I think, ketchup would also be one as well as pulp. Pulp is funny case; AI told it's not non-newtonian, but pulp mill folks told it actually is. So I was thinking if I could build a set-up for known non-newtonian substance. So far only no-newtonian thing in my ´Phoenix FD set-ups has been dragging the non-newtonian slider all the way up.

[JuhaHo]

I made a little test. I don't know what I'm doing wrong here.

[georgi.zhekov]

Hey,

Not really sure what is going on in the image? Can you give us a bit more info?

[JuhaHo]

Thanks Georgi,

I wanted to test non-newtonian liquid behavior since most of my fluid animations are using that. I made here a little test in which I filled this vase with non-newtonian liquid. Then I dropped and iron ball into it expecting it to float a bit and the start sinking. The liquid is not affecting the speed much if any.

[JuhaHo]

Here's what I was trying to achieve. Do You think it's possible with PhoenixFD

https://www.youtube.com/shorts/i6D74...?feature=share

[zdravko_pavlov1]

Hi,

Do you use active bodies for the objects that fall into the liquid?

[JuhaHo]

Yes, I did. I wonder if there is a way to delay the time, when the object is released.

I tested multiplying the fluid density by ten. Now the object floats forever as in real life it would slowly start sinking.

[zdravko_pavlov1]

Hi.

You can animate the Make Active Body Static option so that it is static in the beginning. Then it is released in a specified frame.



And it is actually easier to do that in the Phoenix Property Lister. (You can scrub through the timeline when the lister is opened)



The Active Bodies are not affected by the viscosity of the liquid. They are only affected by the density of the fluid and their weight.
The so-called "Non-Newtonian" feature is just a mechanism that aims to improve the wetting of objects with highly viscous fluids. It simply lowers the viscosity where the fluid isn't moving or it moves slowly. Usually when it collides and interacts with geometry.

What you can do is to make a couple of tuners. The first one increases the viscosity when the liquid particles are moving above a given threshold. And the second one, setting it back to 0 when they move slowly.

Like this:
https://gyazo.com/4537ebf0b55a714016724355e417da47

This won't solve the interaction with the active body. As I mentioned, the AB doesn't account for viscosity. And you have to animate the density of the liquid in the AB Solver.

[JuhaHo]

I didn't get this working. Are there any tutorials covering this area?

However I have other issue. My solution was to simulate this first without active bodies. Then I activated active bodies and started simulation again on desired dropping time. This introduced a new issue. When simulated like this, the first key of the active body is also the last key. My workaround was to move this and the second key to beginning of the timeline by using the Dope Sheet.

[georgi.zhekov]

I'm not aware of any tuts around this at this point, but we can make some in the future. Which part do you have trouble with?

[JuhaHo]

Thanks,

I didn't understand how the keys are created when toggling between static body and active body.

[georgi.zhekov]

Here is how to animate it.

[JuhaHo]

Thnaks Georgi,

For some reason this don't work with me; no keys are being created. Instead it turns animate toggle off.

Actually it worked. It depends if it's active in the beginning - so it animates only one-way.