How to set a desired Timestep for ViscElMat

Asked by Ataollah Nateghi on 2019-02-23

Hello
I am writing this simple code where a sphere is falling down under gravity acceleration inside a box.. It is very clear how material properties are effecting the timestep when FrictMat is being used but about ViscElMat I am confused. Do I need to use GlobalStiffnessTimeSteppe and how should I use it.
Thanks in advance.

# DATA COMPONENTS
#sMat=O.materials.append(ViscElMat(cn=0,cs=0,kn=10.0e5,ks=10.0e5,frictionAngle=30,density=1650,label="sMat"))
sMat=O.materials.append(FrictMat(young=30e5,poisson=.2,frictionAngle=.6,label="sMat"))

s=utils.sphere((-0.0025,0,0),RR,material=sMat) #-0.0044

O.bodies.append(geom.facetBox((aa,bb,cc),(AA,BB,CC),wallMask=63)) #63 closes all the directions

O.bodies.append([
   s
])

# FUNCTIONAL COMPONENTS

# simulation loop -- see presentation for the explanation
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
   InteractionLoop(
      [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom()], # collision geometry
      #[Ip2_FrictMat_FrictMat_FrictPhys()], # collision "physics"
      [Ip2_ViscElMat_ViscElMat_ViscElPhys()], # collision "physics"
      #[Law2_ScGeom_FrictPhys_CundallStrack()] # contact law -- apply forces
      [Law2_ScGeom_ViscElPhys_Basic()]
   ),
  # GlobalStiffnessTimeStepper(viscEl=ture),
   NewtonIntegrator(gravity=(10,0,0),damping=0.0)
]

yade.qt.Controller()

Question information

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Last query:
2019-02-23
Last reply:
2019-03-01
Jérôme Duriez (jduriez) said : #1

Hi,

Did you use GlobalStiffnessTimestepper.viscEl (set to "True" instead of "ture" ;-) ).

The doc says it allows GlobalStiffnessTimestepper to account for visco elastic interactions, but I do not have first hand experience with it.

As a general remark, I do not think it is possible to "set timestep to a desired value" generally speaking (outside some educated tricks)

Jérôme

[*]https://yade-dev.gitlab.io/trunk/yade.wrapper.html#yade.wrapper.GlobalStiffnessTimestepper.viscEl

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