betonlmgc.py

# 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

# TESTCASE DESCRIPTION
# Mixing of grains in a rotating drum.
# This example shows how to set boundary conditions as a function of some parametres.
# A boolean parametre give the possibility to use lmgc90 to solve contacts or not.

#variable to use lmgc or not
use_lmgc = 1
from migflow import fluid
from migflow import scontact
if use_lmgc :
    from migflow import lmgc2Interface
import numpy as np
import os
import time
import shutil

def genInitialPosition(filename, r, rout, rhop) :
    """Create a container to initialize particles and write particles in an initial output file.

    Keyword arguments:
    filename -- directory to write the output file
    r -- max particle radius
    rout -- outer radius of the drum
    rhop -- particle density
    """
    # Grains structure builder
    p = scontact.ParticleProblem(2)
    # Load mesh.msh file specifying physical boundaries names
    p.load_msh_boundaries("mesh.msh", ["Outer", "Inner"])

    # First layer of grains
    # Definition of the points where the grains are located
    x = np.arange(rout, -rout, 2 * -r)
    y = np.arange(-rout, -2*rout/3., 2 * r)
    x, y = np.meshgrid(x, y)
    R2 = x**2 + y**2
    # Condition to be inside the outer boundary
    keep = R2 < (rout-r)**2
    x = x[keep]
    y = y[keep]
    # Add a grain at each centre position
    for i in range(x.shape[0]) :
        p.add_particle((x[i], y[i]), r, r**2 * np.pi * rhop);
    
    # Second layer of grains
    # Definition of the points where the grains are located
    x = np.arange(rout, -rout, -r)
    y = np.arange(-2*rout/3.+r, -rout/2.,  r)
    x, y = np.meshgrid(x, y)
    # Condition to be inside the outer boundary
    R2 = x**2 + y**2
    keep = R2 < (rout-r)**2
    x = x[keep]
    y = y[keep]
    # Add a grain at each centre position
    for i in range(x.shape[0]) :
        p.add_particle((x[i], y[i]), r/2., r**2/4. * np.pi * rhop);
    
    # Third layer of grains
    # Definition of the points where the grains are located
    x = np.arange(rout, -rout, 2 * -r/3)
    y = np.arange(-rout/2.+r, -5*rout/12., 2 * r/3)
    x, y = np.meshgrid(x, y)
    R2 = x**2 + y**2
    # Condition to be inside the outer boundary
    keep = R2 < (rout-r/3)**2
    x = x[keep]
    y = y[keep]
    # Add a grain at each centre position
    for i in range(x.shape[0]) :
        p.add_particle((x[i], y[i]), r/3, r**2 /9*np.pi*rhop);
    p.write_vtk(filename,0,0)

# Define output directory
outputdir = "output"
if not os.path.isdir(outputdir) :
    os.makedirs(outputdir)

# Physical parameters
g = -9.81                                       # gravity
rhop = 1600                                     # grains density
r = 397e-6/2                                    # grains radius
rho = 1e3                                       # fluid density
nu = 1e-4                                       # kinematic viscosity

# Numerical parameters
outf = 1                                        # number of iterations between output files
dt = 5e-3                                       # time step
tEnd = 100                                      # final time

# Geometrical parametres
rout = 0.0254                                   # outer boundary

# 
# PARTICLE PROBLEM
#
# Initialise grains
genInitialPosition(outputdir, r, rout, rhop)
if use_lmgc :
    friction = 0.1                                    # friction coefficient
    lmgc2Interface.scontactToLmgc90(outputdir,0,friction)
    p = lmgc2Interface.LmgcInterface()
else :
    p = scontact.ParticleProblem(2)
    p.read_vtk(outputdir,0)

# Initial time and iteration
t = 0
ii = 0

#
# FLUID PROBLEM
#
fluid = fluid.FluidProblem(2,g,[nu*rho],[rho])
#Set the mesh geometry for the fluid computation
fluid.load_msh("mesh.msh")
fluid.set_strong_boundary("Outer",0,lambda x : -4*x[:, 1])
fluid.set_strong_boundary("Outer",1,lambda x : 4*x[:, 0])
fluid.set_strong_boundary("Inner",0,0)
fluid.set_strong_boundary("Inner",1,0)
fluid.set_strong_boundary("PtFix",2,0)
fluid.set_weak_boundary("Inner","Wall")
fluid.set_weak_boundary("Outer","Wall")
#Set location of the grains in the mesh and compute the porosity in each computation cell
fluid.set_particles(p.mass(), p.volume(), p.position(), p.velocity())
fluid.export_vtk(outputdir,0,0)

tic = time.time()
fluid.set_particles(p.mass(), p.volume(), p.position(), p.velocity())

#
# COMPUTATION LOOP
#
while t < tEnd :
    # Fluid solver
    fluid.implicit_euler(dt)

    # Computation of the new velocities
    forces = fluid.compute_node_force(dt)
    vn = p.velocity() + forces*dt/p.mass()
    vmax = np.max(np.hypot(vn[:, 0], vn[:, 1]))
    # Number of contact sub time step
    nsub = max(1, int(np.ceil((vmax*dt*4)/min(p.r()))))
    print("NSUB", nsub,"VMAX",vmax, "VMAX * dt", vmax * dt, "r", min(p.r()))
    # NLGS iterations
    for i in range(nsub) :
        tol = 1e-6                                #numerical tolerance for grains intersection
        p.iterate(dt/nsub, forces, tol)

    # Localisation of the grains in the fluid
    fluid.set_particles(p.mass(), p.volume(), p.position(), p.velocity())
    t += dt

    # Output files writting
    if ii %outf == 0 :
        ioutput = int(ii/outf) + 1
        p.write_vtk(outputdir, ioutput, t)
        fluid.export_vtk(outputdir, t, ioutput)
    ii += 1
    print("%i : %.2g/%.2g (cpu %.6g)" % (ii, t, tEnd, time.time()-tic))