new separation test

testcases/separation/rest.py

+# Marblesbag - Copyright (C) <2010-2018>
+# <Universite catholique de Louvain (UCL), Belgium
+#  Universite de Montpellier, France>
+# 	
+# List of the contributors to the development of Marblesbag: see AUTHORS file.
+# Description and complete License: see LICENSE file.
+# 	
+# This program (Marblesbag) is free software: 
+# you can redistribute it and/or modify it under the terms of the GNU Lesser General 
+# Public License as published by the Free Software Foundation, either version
+# 3 of the License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+# 
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program (see COPYING and COPYING.LESSER files).  If not, 
+# see <http://www.gnu.org/licenses/>.
+
+#!/usr/bin/env python
+from marblesbag import fluid as fluid
+from marblesbag import scontact2
+
+import numpy as np
+import os
+import time
+import shutil
+import random
+#Physical parameters for the drops are the ones presented by Metzger et al. (2007) "Falling clouds of particles in viscous fluids"
+
+
+outputdir = "output"
+if not os.path.isdir(outputdir) :
+    os.makedirs(outputdir)
+
+t = 0
+ii = 0
+
+
+#physical parameters
+g =  -9.81                                      # gravity
+rho = 1000 
+rho1 = 1001                                     # fluid density
+nu = 1e-3                                   # kinematic viscosity
+mu = nu*rho                                     # dynamic viscosity
+tEnd = 100000                                     # final time
+
+#numerical parameters
+lcmin = .1                                  # mesh size
+dt = 0.1                                       # time step
+alpha = 1e-6                                    # stabilization coefficient
+epsilon = alpha*lcmin**2 /nu                    # stabilization parametre
+print('epsilon',epsilon)
+
+shutil.copy("mesh.msh", outputdir +"/mesh.msh")
+
+outf = 1                                       # number of iterations between output files
+u0,v0,q0 = 0,1,2
+u1,v1,q1 = 3,4,5
+p = 6
+#Object fluid creation + Boundary condition of the fluid (field 0 is horizontal velocity; field 1 is vertical velocity; field 2 is pressure)
+#Format: strong_boundaries = [(Boundary tag, Fluid field, Value)
+strong_boundaries = [
+        ("Top",u0,u0,0),
+        ("Top",u1,u1,0),
+        ("PtFix",q0,p,0),
+        ("Bottom",u0,u0,0),
+        ("Bottom",u1,u1,0),
+        ("Left",u0,u0,0),
+        ("Left",u1,u1,0),
+        ("Right",u0,u0,0),
+        ("Right",u1,u1,0),
+        ("Top",v0,v0,0),
+        ("Top",v1,v1,0),
+        ("Bottom",v0,v0,0),
+        ("Bottom",v1,v1,0),
+        ("Left",v0,v0,0),
+        ("Left",v1,v1,0),
+        ("Right",v0,v0,0),
+        ("Right",v1,v1,0)
+        ]
+fluid = fluid.fluid_problem("mesh.msh",g,[nu*rho,nu*rho1],[rho,rho1],epsilon,strong_boundaries,2)
+ii = 0
+t = 0
+
+#set initial_condition
+x = fluid.coordinates()
+s = fluid.solution()
+s[:,2] = .5
+s[:,5] = .5
+s[:,6] = -rho*g*(1-x[:,1])
+
+
+fluid.export_vtk(outputdir,0,0)
+
+ii = 0
+tic = time.clock()
+while ii < 100 : 
+    #Fluid solver
+    fluid.implicit_euler(dt)
+    t += dt
+    #Output files writting
+    if ii %outf == 0 :
+        ioutput = int(ii/outf) + 1
+        fluid.export_vtk(outputdir, t, ioutput)
+    ii += 1
+    print("%i : %.2g/%.2g (cpu %.6g)" % (ii, t, tEnd, time.clock() - tic))
+    
+s = fluid.solution()
+x = fluid.coordinates()
+vel = (s[:,0]-1/(20*nu*rho)*x[:,1]*(1-x[:, 1]))**2
+print('Error', (vel.sum())**.5)
+
+if (vel.sum())**.5<1.5e-3:
+    exit(1)
+else:
+    exit(0)