avalanch2fluidsnofriction.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
# Collapsing of a grain column in fluid. 
# The grain column is initially mixed in sea water while the rest of the domain contain soft water. 
# This test case cannot be runned on its own, it requires the output files of the depot test case (../depot/dep.py) to create a compact column as initial situation
# Positions, masses and radii of graisn are setted in the dep.py file.

from migflow import fluid as fluid
from migflow import scontact
import numpy as np
import os
import time
import shutil
import random

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

# Physical parameters
g = -9.81                                        # gravity
rhop = 1500                                      # particles density
# Soft water
rhof = 1000                                      # sof water density
nuf = 1e-6                                       # soft water kinematic viscosity
# Sea water
rhom = 1050                                      # sea water density
num = 1e-6                                       # sea water kinematic viscosity

# Numerical parameters
outf = 10                                        # number of iterations between output files
dt = 1e-4                                        # time step
tEnd = 1                                         # final time

# 
# PARTICLE PROBLEM
# 
# Particles structure builder to load file created with dep.py
p1 = scontact.ParticleProblem(2)
# Use particles deposit computed by the dep.py file of depot folder
p1.read_vtk("../depot/output",25)
# New particles structure builder to set other boundary conditions than in dep.py
p = scontact.ParticleProblem(2)
p.load_msh_boundaries("mesh.msh", ["Top", "Bottom", "Left", "Right"])
for i in range(len(p1.position()[:,0])):
    p.add_particle((p1.position()[i,0], p1.position()[i,1]), p1.r()[i], p1.r()[i]**2 * np.pi * rhop)
p.write_vtk(outputdir, 0, 0)

# Initial time and iteration
t = 0
ii = 0

# 
# FLUID PROBLEM
#
fluid = fluid.FluidProblem(2,g,[num*rhom,nuf*rhof],[rhom,rhof],coeff_stab=0.001)
# Set the mesh geometry for the fluid computation
fluid.load_msh("mesh.msh")
fluid.set_wall_boundary("Bottom")
fluid.set_wall_boundary("Left")
fluid.set_wall_boundary("Top",pressure=0)
fluid.set_wall_boundary("Right")
# Set location of the particles in the mesh and compute the porosity in each computation cell
fluid.set_particles(p.mass(), p.volume(), p.position(), p.velocity())
# Access to fluid fields and node coordiantes
s = fluid.solution()
x = fluid.coordinates()
# Set initial condition for the concentration
lx = 0.1
for i in range(len(x[:,0])):
    if (x[i,0])<lx:
        s[i,3] = 1
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)

    # Adaptation of the mesh. Args are minimal mesh radius, maximal mesh radius and number of elements
    if (ii%15==0 and ii != 0):
       fluid.adapt_mesh(1e-2,3e-3,10000)

    # 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 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) :
        p.iterate(dt/nsub, forces)  

    t += dt
    fluid.set_particles(p.mass(), p.volume(), p.position(), p.velocity())

    # 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))