Looking for thoughts and opinions on this.. From the horses mouth would be amazing too.

I'm wondering if there are plans to do anything on a grander scale for liquid simulations (not really biblical floods or oceans but smaller scale stuff)? Does anyone think it needs work? I'm looking for solutions to my issue(s) with it not looking to grumble about it not working.

I have to say first up I've only been using H for 12 months so I'm a total beginner with all the problems that brings so the question comes from that perspective. Liquids or rather flip seems to be the only part of H I've not been able to get in any way comfortable with. My experience of liquids pre H is small scale uncomplicated stuff done in realflow, laterly using dyverso. I never used hybrido as the sph solver was fast enough for my needs and I could turn simple stuff out without issue. Flip in H seems like a different beast and I've really got nowhere with it. A fair few voices suggest that flip has things it's good for and things it's not and that seems to be backed up up by the kind of tutorials and masterclasses that are available.

Looking at doing some small garden water feature designs recently and after a few weeks if fidling around with flip I've felt like I should just do it in Realflow to get it done but that seems like a massive cop out and I don't have time or money to use multiple bits of software. Using the result of following a tutorial is a good start but after that I've only to breathe on a setup/parameter and it instantly turns to garbage and advice from forums seems to be unwieldingly varied.

So, more questions than my inital one… Do people who really know about it think liquids need looking at? Is a third party solution a necessary evil at this time? or Is it really just time and experience that one needs to be able to achieve quick, simple small scale liquids.

cheers,

Andi

I think you can get most looks done in FLIP. I do miss the SPH fluids in Houdini, but the particle fluids are an okay-ish
bridge back to that world, for certain things. You want to keep scale in mind. Don't worry about working to real-world scale.
In the past I've managed to get it to do big oceans, small fast rivers, splashes, ice-cream, and honey. So it's all possible,
there's just a few knobs to turn, and finding a good working scale.
Is there a specific type of fluid you are having trouble with at the moment? Could you share an example?


Cheers

L

Scale is an interesting point as I've always tried to work to real world units so my particle separation is heading towards 0.005 or lower. Never tried working at a hacked scale as I've no idea which parameters need tweaking to accommodate it apart from gravity obviously. Is it a smarter move to simulate at an optimum size and scale down the end surface?

I seem to have problems when simulating anything with that has a finer thinner quality to it ending up with volume loss, or clinging to surfaces. I've uploaded a simple test to illustrate what i'm currently trying to create. A garden feature where the water bubbles out the top of a pole and flows down the outside. Simple but the water needs to be the star of the idea.

I've a very rudimentary grasp of what flip is doing… gleaned from Steve Knippings cg circuit flip series, but I've no idea how to debug flips behaviour, or go beyond the basic setups. I know for sure you don't master flips in H with the occasional sim over 12 months, but I've come from bashing stuff out quickly in Softimage and Realflow to taking a fair bit longer in H and the boss is tapping his foot!


cheers,

Andi

Hi Andi

Were you able to make any more progress with this? I am having similar issues trying to do small scale flip simulation, in my case its a liquid in an animtated bottle. I have been digging around in the forum to find a solution, there are a few tricks I found that improved the result but were not totally satisfactory. My main issue is that I am getting volume loss once i cross a million particles. Under a million everything works fine.

Sadly no Jumax, the end result for me being a poor quality sim. I don't really think the small scale liquids are on the side fx radar really if all the disaster movie crews don't need it….

Yeah every step has been a struggle. I solved the volume loss issue, but now when i try to use surface tension it goes crazy and brings back the same issue. one of the new things I learned today was dont try to work in the exact scale, there is a sweet spot between too large and too small. I am currently working at the actual size of the bottle in a meter scene so its quite small. My next step is to scale it up a bit and see how that goes.

I had a look. Your scale is tiny. Just forget about working at real world scale.
So I scaled up everything 5x, and adjusted your emitter velocity so it felt more correct at the bigger scale.

Obviously gravity needs to be 5x, but some things to think about are;
That water feature is meant to be small, so you'd expect surface tension to be a part of it, I turned it on.
Since we are working at a bigger scale, enabling viscosity helps keep the water together a bit more than it should.
It's not perfect, but after 5 mins of playing it at least behaves, is quick to sim, and you can push from there.


Lewis

Thanks tinyhawkus, I'll see where I get with it.


cheers,

A>