tadd functions to set frictional coefficients - sphere - GPU-based 3D discrete element method algorithm with optional fluid coupling
(HTM) git clone git://src.adamsgaard.dk/sphere
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---
(DIR) commit 76aef1aad86deca7d2cb55dd3967abdc91ac30ba
(DIR) parent 800daf5d4a0409bae1d91db072ebca5483051083
(HTM) Author: Anders Damsgaard <anders.damsgaard@geo.au.dk>
Date: Thu, 6 Nov 2014 10:02:54 +0100
add functions to set frictional coefficients
Diffstat:
M python/sphere.py | 32 +++++++++++++++++++++++++++++++
M tests/cfd_tests_darcy_particles.py | 10 +++++++---
2 files changed, 39 insertions(+), 3 deletions(-)
---
(DIR) diff --git a/python/sphere.py b/python/sphere.py
t@@ -3333,6 +3333,38 @@ class sim:
else:
print('Warning: The system is critically dampened (ratio = '
+ str(damping_ratio) + ') in the tangential component.')
+
+ def setStaticFriction(self, mu_s):
+ '''
+ Set the static friction coefficient for particle-particle interactions
+ (`self.mu_s`). This value describes the resistance to a shearing motion
+ while it is not happenind (contact tangential velocity zero).
+
+ :param mu_s: Value of the static friction coefficient, in [0;inf[.
+ Usually between 0 and 1.
+ :type mu_s: float
+
+ See also: :func:`setDynamicFriction(mu_d)`
+ '''
+ self.mu_s[0] = mu_s
+
+ def setDynamicFriction(self, mu_d):
+ '''
+ Set the dynamic friction coefficient for particle-particle interactions
+ (`self.mu_d`). This value describes the resistance to a shearing motion
+ while it is happening (contact tangential velocity larger than 0).
+ Strain softening can be introduced by having a smaller dynamic
+ frictional coefficient than the static fricion coefficient. Usually this
+ value is identical to the static friction coefficient.
+
+ :param mu_d: Value of the dynamic friction coefficient, in [0;inf[.
+ Usually between 0 and 1.
+ :type mu_d: float
+
+ See also: :func:`setStaticFriction(mu_s)`
+ '''
+ self.mu_d[0] = mu_d
+
def bond(self, i, j):
'''
(DIR) diff --git a/tests/cfd_tests_darcy_particles.py b/tests/cfd_tests_darcy_particles.py
t@@ -123,7 +123,9 @@ orig.num[2] /= 2
orig.L[2] /= 2.0
orig.id('darcy_fluidization')
orig.cleanup()
-orig.initTemporal(total=0.005, file_dt=0.001)
+orig.setStiffnessNormal(36.4e9)
+orig.setStiffnessTangential(36.4e9/3.0)
+orig.initTemporal(total=0.0005, file_dt=0.0001)
orig.initFluid(cfd_solver=1)
orig.setFluidBottomNoFlow()
orig.g[2] = -10.0
t@@ -134,7 +136,7 @@ orig.run(verbose=False)
#orig.writeVTKall()
py = sphere.sim(sid = orig.sid, fluid = True)
py.readlast(verbose=False)
-test(orig.w_x[0] > py.w_x[0], 'Wall movement:\t')
+test(orig.w_x[0] > py.w_x[0], 'Wall movement:\t\t')
print("### Fluidization test: Transient, gravity, Dirichlet+Dirichlet BCs")
t@@ -145,7 +147,9 @@ orig.num[2] /= 2
orig.L[2] /= 2.0
orig.id('darcy_fluidization')
orig.cleanup()
-orig.initTemporal(total=0.005, file_dt=0.001)
+orig.setStiffnessNormal(36.4e9)
+orig.setStiffnessTangential(36.4e9/3.0)
+orig.initTemporal(total=0.0005, file_dt=0.0001)
orig.initFluid(cfd_solver=1)
orig.g[2] = -10.0
#orig.k_c[0] = numpy.mean(orig.radius)**2/540.0