Hey I'm a student working on my reel. Right now I'm animating a street getting flooded with water. I have larger geometry (representing buildings) that wont be affected by the water but I want my smaller geometry (representing cars) to get carried away by the flood. I've tried RBD, RBD Breakable and a few other things but I cant get it to work. any tips?

You need to turn up the Feedback Scale on the flip solver. Its under the Solver tab in the Volume motion tab.


zak

hi, i got another question about feedback scale. what does it really take into account if one floats or not? i once touched on realflow where mass of the objects are used to determine if it floats or not. basically, similar to buoyancy, if the object has less mass than the water (1000) it floats and those with more sinks.

thank you

Im no expert, but to my understanding, RBDs wont actually float on top of flips. I believe what happens is that there is a force put on the objects by the fluid that is multiplied by the feedback scale. This is designed to work so that a feedback scale of 1 will apply a reasonable amount of force to an object with the same density as the fluid. I'm sure it is much more complex than this, but to my understanding there is no actually buoyancy.

If you wanted actually buoyancy, or at least something closer, you could try using variable density flips for all of it. (Make an extremely viscous flip with very low density for your RBD)


zak

Hi Guys,

I've managed to get my rigid bodies object floating on flip fluids, how ever they seem to freeze after a certain amount of time. It's like they ran out of battery and just stop.

I have three objects and they all stop at different times. Any ideas what is causing this?

Turn off Enable Sleeping under Collisions>Bullet Data

THANKS PradeepBarua for the answer, that solved it

Another related question, What is the best way of setting an initial state for flip fluid sim? Is is saving a .sim file and then loading this in?

Thanks1

cgcris
Another related question, What is the best way of setting an initial state for flip fluid sim? Is is saving a .sim file and then loading this in?

Thanks1

Yes, you are right. This's only way to set initial state.

Ok, I got this thanks!

What is the easiest or more efficient way of getting to that initial state?

If I have big amount of particle I assume it could take a long time to get to a certain frame. Is it an option to animate the particle separation in order to cheat it? Maybe upping the res a few frames before arriving to the initial state..