(solved)when FLIP collide with RBD, it explosion

   12524   12   3
User Avatar
Member
102 posts
Joined: March 2013
Offline
I tried use a FLIP to push RBD (use bullet solver), but the RBD objects just bounce off at collided moment.
and if RBD inside the FLIP it will explosion. you can see it in this video:
http://youtu.be/4f9urniAa5g [youtu.be]

I tried to find the reason with check the “collision velocity” in the Visualization but still can't understand what's happen…
is there a way can fix this problem? I need some help, please
thanks!

iGou
Edited by - April 8, 2013 10:10:48
User Avatar
Member
53 posts
Joined: May 2010
Offline
i have the same problem, it stable only a few frames
User Avatar
Member
67 posts
Joined: Oct. 2011
Offline
Hi there iGou,
Can you post your hip file ?
it would be easier to find the problem!
thx
lari

lari
User Avatar
Member
102 posts
Joined: March 2013
Offline
Hi Lari,
here is a remade file but have the same problem, I didn't save the original one.
I think I only changed the density (FLIP and RBD both) because the default density is too weak to push those boxes.

thank you!

iGou

Attachments:
FLIPtest.rar (116.7 KB)

User Avatar
Member
20 posts
Joined: Dec. 2011
Offline
Have you tryed setting the boxes as polygons and give them some itinerations?
User Avatar
Member
102 posts
Joined: March 2013
Offline
Hi Traiano,
I just go to tried setting as polygons or polygons mesh, and increase those axis division but it's still exploded.
I once think that explosion always happen in the FLIP container boundary, but after some test I'm not sure if the boundary is reason…
http://youtu.be/OB_wgP38yWI [youtu.be]
in this time I tried to move ground upper on container and boxes in the middle but still explode…

btw, I don't know what's “itinerations”, you mean axis division?

thanks for advice, I'll keep to try find the reason

Attachments:
FLIPtest2.rar (121.1 KB)

User Avatar
Member
245 posts
Joined: Sept. 2011
Offline
The density of the boxes are too low which cause incorrect physical attributes.
Now you have 5000 density for water vs 50 density for box..

Set density back to 1000 for flip object node (not 100% required) but for the RBD object it is better to put back to 1000 for now.
Change the feedback scale in the flip solver to 1 instead. With 1 means 100% force feedback.
0.9 would be 90%
1.1 would be 110% etc..

Feedbackscale can be found here:

flipsolver node: volume motion –> solver –> feedback scale

Higher feedback scale than 1 can cause objects to float, this is what I created a few months ago..

http://www.youtube.com/watch?v=oqVniDdjfNE [youtube.com]
User Avatar
Member
102 posts
Joined: March 2013
Offline
I set boxes density very low because it too heavy so FLIP can't push them, but after change feedback to 1… amazing! even boxes is so heavy FLIP can move them, wow!!!there is still a little explode but it's find, just a little.
thanks Johnnycore

btw, I'm wonder why you know that I just got another problem about floatingXD your vedio is so cool, helpful
User Avatar
Member
245 posts
Joined: Sept. 2011
Offline
I think the little explosion may still occur because the density of the flip object node might still be set to 5000 I suppose?

By default the mass of FLIP and RBD/Bullet are the same which is:

mass = volume/density

So when you set density of flip object to 5000 and RBD object to 1000 the flip fluid will be 5 times more heavier than the RBD object when they have the same volume.

Hope this helps.
User Avatar
Member
102 posts
Joined: March 2013
Offline
Yes, it is 5000. turn back to 1000 then the explosion not occur anymore and have a funny floating motion!

really helpful, thank you!!
User Avatar
Member
68 posts
Joined: May 2013
Offline
In Version 13.0 this seems not to be working anymore what's changed?
multiple
Scoord and Tcoord
unrecognized errors on load

running sim boxes don't move FLIPtest2.hipnc

sure I changed the density of the fluid to 1000
/obj/explossion1/AutoDopNetwork/flipfluidobject/density

I've also changed
/obj/explossion1/AutoDopNetwork/box1/density
to 1000 as well

Boxes don't move. Why?
The liquid does go around the boxes.

I've tried changing the ridigitbodysolver1 to RBD mode = no change

Deleted the RBD last 3 nodes including create_fractured_group (An Assemble node) and the appropriate solver in the AutoDopNetwork

to see how it does it now…
select RBD click shelf tool Rigid Bodies > RBD Object

This skips the Assemble node but also fails to move the boxes when the fluid collides. reduced frictions and density in RDBObject physics tab also nothing moving.

So anyway I could go on but somethings changed possibly broken in 13.0.547?! It should just work.

Are you suppose to do something completely different now?
User Avatar
Member
245 posts
Joined: Sept. 2011
Offline
Try change the feedback scale, by default its set to 0 meaning it cannot push other objects.

flipsolver node: volume motion –> solver –> feedback scale

Dont overdo this setting, 1 means 100%, 0 means 0%

Ofcourse you can enter 5000% as you like
User Avatar
Member
68 posts
Joined: May 2013
Offline
Yes I just discovered that.
It took me 2 days to find it.
Thank you for answering so quickly I was just coming back to report my findings.
I'm sure it will help others to have this on record here.
  • Quick Links