Water droplet on surface - flip oddness

   9586   3   2
User Avatar
Member
2 posts
Joined: April 2012
Offline
Hi!

I'm a bit new to the latest houdini FLIP setup, and wanted to do a simple test of emitting a droplet of water and letting it fall and collide with a surface. I'm experiencing some oddness with the sim that I'm unable to solve; basically my droplet looks like it gets ‘eaten away’ before it falls too far, unless I reduce my resolution settings for the flip sim (which I don't want to have to do). I'm attaching a file that shows what I'm doing; it's been built as a result of following the posted Waterfall Flip tutorial on the site here.

Anyone know what I might be doing wrong?

Thanks!

Attachments:
dripTest_v01.hip (1.0 MB)

User Avatar
Staff
817 posts
Joined: July 2006
Offline
If you watch the droplet as it falls relative to the bounding box, it's basically
“outrunning” the bounding box as it speeds up. To correct this, you need to increase the Max Cells to Extrapolate parameter on the Volume Motion | Solver tab. From the help:


Max Cells to Extrapolate

The number of non-fluid cells that should be filled with velocity values on
the non-fluid side of the velocity field. Increase this value for very fast-
moving fluids and/or a low number of substeps.


Alternatively (or additionally) you can increase the number of substeps, so the fluid doesn't move as far in each timestep.
User Avatar
Member
34 posts
Joined: Oct. 2007
Offline
1.your gravity force is too high 98 and it's on Z usually it will be in Y -9.8
2.Close the Boundaries
Select FlipFluidObject -> Initial Data -> Closed Boundaries
User Avatar
Member
2 posts
Joined: April 2012
Offline
johner, thanks very much, that's exactly what I was after. Cheers!
  • Quick Links