I've created this simulation yesterday:
http://www.youtube.com/watch?v=QcGEWtwLztU [youtube.com]

And I want to re-sim this simulation because all the teapots are floating upside down.. does anyone have an idea how I can fix something like that?

I tried changing the center of mass but I dont think I changed it properly or I doesnt work. Would be really nice if I was able to see the center of mass so I can have a bit of indication whats happening!

For the rest.. im clueless!

center of mass is what comes to mind first. dont have houdini in front of me but i remember when doing this i couldnt get it to work by changing it explicitly or even using point expressions.. just taking the expression that was there and subtracting a number from it worked iirc.

you could also maybe try and add a point attribute to your teapots called density, and make them less dense on the bottom and more dense on the top. havent tried that but maybe it will work?

Ah yes thanks! seems to work for me!
Should have tried it earlier with subtracting from the expression makes so much sense!

But still it would be nice to be able to see your center of mass because im just trying out some values..

Is there any way to visualize this?

After some tweaking got them floating correctly!

http://www.youtube.com/watch?v=ot_SuBC2eRM&list=UUZXUssGSY19udsDX5L20A5g&index=3&feature=plcp [youtube.com]

sweet! although, it does look awkward now that they dont flip over.. they ARE indeed bigger on the bottom! glad it worked though!