poiseuille.py 3.5 KB
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# MigFlow - Copyright (C) <2010-2018>
# <Universite catholique de Louvain (UCL), Belgium
#  Universite de Montpellier, France>
#
# List of the contributors to the development of MigFlow: see AUTHORS file.
# Description and complete License: see LICENSE file.
#
# This program (MigFlow) 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 migflow import fluid as mbfluid
from migflow import time_integration
import numpy as np
import os
import subprocess
import time
import shutil
import random
import unittest

dir_path = os.path.dirname(os.path.realpath(__file__))
os.chdir(dir_path)
# 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)

subprocess.call(["gmsh", "-2", "mesh.geo","-clscale","2"])
t = 0
ii = 0


#physical parameters
g =  np.array([0,0])                                      # gravity
rho = 1000                                      # fluid density
nu = 1e-3                                   # kinematic viscosity
mu = nu*rho                                     # dynamic viscosity
tEnd = 100000                                     # final time

#numerical parameters
lcmin = .1                                  # mesh size
dt = 10                                       # time step
alpha = 1e-4                                    # 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

#Object fluid creation + Boundary condition of the fluid (field 0 is horizontal velocity; field 1 is vertical velocity; field 2 is pressure)
fluid = mbfluid.FluidProblem(2,g,nu*rho,rho)
fluid.load_msh("mesh.msh")
fluid.set_open_boundary("LeftUp",velocity=[lambda x : 1/(20*mu)*x[:,1]*(1-x[:, 1]),0])
fluid.set_open_boundary("LeftDown",velocity=[lambda x : 1/(20*mu)*x[:,1]*(1-x[:, 1]),0])
fluid.set_wall_boundary("Bottom",velocity=[0,0])
fluid.set_wall_boundary("Top",velocity=[0,0])
fluid.set_open_boundary("RightUp",pressure=0)
fluid.set_open_boundary("RightDown",pressure=0)


ii = 0
t = 0

#set initial_condition

fluid.export_vtk(outputdir,0,0)

ii = 0
tic = time.time()
while ii < 100 :
    #Fluid solver
    time_integration.iterate(fluid,None,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.time() - tic))

s = fluid.solution()
x = fluid.coordinates()
vel = (s[:,0]-1/(20*nu*rho)*x[:,1]*(1-x[:, 1]))**2
vS = np.sum((1/(20*nu*rho)*x[:,1]*(1-x[:, 1]))**2)
print('Error', (vel.sum())**.5)

self.assertLess(vel.sum()**.5,(vS**0.5)/50, "error is too large in Poiseuille")