This is a well-know issue in explicit methods. Fortunately, Vaclav wrote
a chapter on this for the case of DEM. :-)
https://www.yade-dem.org/sphinx/formulation.html#stability-considerations
Bruno
On 08/07/10 20:35, Michael Jensen wrote:
might I ask how you know if your timestep is too large? do you
compare your results with experiment? or are there funky results that
you have learned to associate with time steps that are too big?
--- On *Thu, 7/8/10, Anton Gladky /<[email protected]>/* wrote:
From: Anton Gladky <[email protected]>
Subject: Re: [Yade-users] hello? -help with a spinning bucket!
To: [email protected]
Received: Thursday, July 8, 2010, 2:10 PM
Hi,
this is a more-less normal time step for simulations.
Sometimes I have to do:
O.dt = 0.1*pWavetimestep
2010/7/8 Michael Jensen <[email protected]
</mc/[email protected]>>
one thing that I would be particularly interested in is how
the formula on this page:
https://www.yade-dem.org/sphinx/yade.utils.html#yade.utils.PWaveTimeStep
for spherepwavetimestep is computed.
2.8284271247461903e-07 is a very small number, meaning a huge
number of iterations are required (almost 10 million) before a=20
single second goes by in the simulation. that's a hell of a lot
of iterations! for one second! is it really necessary?
-mike..
--- On *Thu, 7/8/10, Bruno Chareyre
/<[email protected]
</mc/[email protected]>>/* wrote:
From: Bruno Chareyre <[email protected]
</mc/[email protected]>>
Subject: Re: [Yade-users] hello? -help with a spinning bucket!
To: [email protected]
</mc/[email protected]>
Received: Thursday, July 8, 2010, 10:13 AM
It seems to me that if I put some beads into a container,
then tip the container, the angle at which they start
flowing is the angle of internal friction.. I am not at
all sure of this, it seems far to simple.
Not really. Angle of repose corresponds to "internal
packing friction", which "depends on" contact friction but
is not equal.
Most materials have contact friction around 30°. Put this
value at contact in a loose sphere packing and you will
get an internal friction around 18°.
Anyway, you should get realistic results as soon as you
define a decent friction (say between 10 and 40), this is
not a crucial parameter yet.
Bruno
-----Inline Attachment Follows-----
_______________________________________________
Mailing list: https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
Post to : [email protected]
<http://mc/[email protected]>
Unsubscribe : https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
More help : https://help.launchpad.net/ListHelp
_______________________________________________
Mailing list: https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
Post to : [email protected]
</mc/[email protected]>
Unsubscribe : https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
More help : https://help.launchpad.net/ListHelp
-----Inline Attachment Follows-----
_______________________________________________
Mailing list: https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
Post to : [email protected]
</mc/[email protected]>
Unsubscribe : https://launchpad.net/~yade-users
<https://launchpad.net/%7Eyade-users>
More help : https://help.launchpad.net/ListHelp
_______________________________________________
Mailing list: https://launchpad.net/~yade-users
Post to : [email protected]
Unsubscribe : https://launchpad.net/~yade-users
More help : https://help.launchpad.net/ListHelp
_______________________________________________
Mailing list: https://launchpad.net/~yade-users
Post to : [email protected]
Unsubscribe : https://launchpad.net/~yade-users
More help : https://help.launchpad.net/ListHelp
