yade-dev team mailing list archive

[Chiara Modenese <c.modenese@xxxxxxxxx>]

Am not used to PFC, but I read this line in your script:

damp viscous normal visc_damp_normal notension on

notension on means (I guess) that no tension is allowed in the normal
contact. Actually, I am thinking to add the same option to the Hertz model
because at the moment I simply apply a damping force which however may cause
attractive forces (in quasi-static conditions it should be not of any worry
but in dynamic cases can play a role). However, this could explain the
different in your results. Please, try to isolate the different types of
damping and test them separately to see where the difference comes from.

Chiara


On 7 July 2011 13:11, Chiara Modenese <c.modenese@xxxxxxxxx> wrote:

> Hi,
>
> I see you are including both contact viscous damping as well as global (or
> local as called in PFC) damping in your test. First of all, make sure that
> everything works without any damping (does it?). Second, check that the
> formulations you are comparing are precisely the same when damping is
> included.
> Please, do these checks and let us know.
>
> Thanks, Chiara
>
>
>
> On 7 July 2011 12:35, Christian Jakob <806944@xxxxxxxxxxxxxxxxxx> wrote:
>
>> ** Attachment added: "scripts and log files for PFC and for YADE"
>>
>> https://bugs.launchpad.net/bugs/806944/+attachment/2195336/+files/two-spheres-damping-test.tar.gz
>>
>> --
>> You received this bug notification because you are a member of Yade
>> developers, which is the registrant for Yade.
>> https://bugs.launchpad.net/bugs/806944
>>
>> Title:
>>  different behavoir of Hertz model while comparing PFC and YADE
>>
>> Status in Yet Another Dynamic Engine:
>>  New
>>
>> Bug description:
>>  Hello,
>>
>>  During verifiing my model I compared output from PFC 4.0 with the
>>  output from YADE (bzr2877 on Debian Squeeze 64bit). There I found a
>>  different behavior between these two programs. I dont know if this is
>>  a bug or not, but I hope someone can explain the different behavior.
>>
>>  The model itself is very simple. There are two spheres, an upper one and
>> a lower one. The lower one is fixed and the upper one is falling down to the
>> lower one, collides and jumps back. The value of interest is the flyback
>> height of the upper particle.
>>  In PFC I measure higher values of flyback height, then in YADE (see
>> log-files in the attachment).
>>
>>  Can someone tell me why there is a difference in the flyback height?
>>  (input parameters are the same for both programs ... see
>> caller_two-spheres-jumping.dat for PFC and two-spheres.py for YADE)
>>
>>  Regards,
>>
>>  Christian Jakob
>>
>> To manage notifications about this bug go to:
>> https://bugs.launchpad.net/yade/+bug/806944/+subscriptions
>>
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>
>

-- 
You received this bug notification because you are a member of Yade
developers, which is the registrant for Yade.
https://bugs.launchpad.net/bugs/806944

Title:
  different behavoir of Hertz model while comparing PFC and YADE

Status in Yet Another Dynamic Engine:
  New

Bug description:
  Hello,

  During verifiing my model I compared output from PFC 4.0 with the
  output from YADE (bzr2877 on Debian Squeeze 64bit). There I found a
  different behavior between these two programs. I dont know if this is
  a bug or not, but I hope someone can explain the different behavior.

  The model itself is very simple. There are two spheres, an upper one and a lower one. The lower one is fixed and the upper one is falling down to the lower one, collides and jumps back. The value of interest is the flyback height of the upper particle.
  In PFC I measure higher values of flyback height, then in YADE (see log-files in the attachment).

  Can someone tell me why there is a difference in the flyback height?
  (input parameters are the same for both programs ... see caller_two-spheres-jumping.dat for PFC and two-spheres.py for YADE)

  Regards,

  Christian Jakob

To manage notifications about this bug go to:
https://bugs.launchpad.net/yade/+bug/806944/+subscriptions