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
'''
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 scontact2
from pylmgc90 import pre
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                                      #grains 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-3                                      #time step
tEnd      =  1                                         #final time

#Grains structure builder to load file created with dep.py
p1        = scontact2.ParticleProblem()
#Use grains deposit computed by the dep.py file of depot folder
p1.read_vtk("../depot/output",25)
#New Grains structure builder to set other boundary conditions than in dep.py
p         = scontact2.ParticleProblem()
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 is the function builder of the fluid class
Args:     -g             : gravity
          -viscosity     : list of fluid phases viscosities
          -density       : list of fluid phases densities
          -coeffStab     : stabilisation parametre to limit overshoots in concentration field (optional)
'''
fluid     =  fluid.fluid_problem(g,[num*rhom,nuf*rhof],[rhom,rhof],coeffStab=0.001)
#Set the mesh geometry for the fluid computation
fluid.load_msh("mesh.msh")

'''
set_strong_boundary is the function setting the strong boundaries (=constraints) for the fluid problem
Args:     -Tag           : physical tag (set in the mesh.geo file) of the boundary on which you want to add a constraint
          -Field         : O: x-velocity; 1: y-velocity; 2: pressure
          -Value         : value assigned to the specified field on the specified boundary
'''
fluid.set_strong_boundary("Top",2,0)
fluid.set_strong_boundary("Top",1,0)
fluid.set_strong_boundary("Bottom",1,0)
fluid.set_strong_boundary("Right",0,0)
fluid.set_strong_boundary("Left",0,0)
'''
set_weak_boundary is the function setting the weak boundaries (=normal fluxes) for the fluid problem
Args:     -Tag           : physical tag (set in the mesh.geo file) of the boundary on which you want to add a constraint
          -Bnd Type      : boundaries can be of type: wall, inflow, outflow
'''
fluid.set_weak_boundary("Bottom","Wall")
fluid.set_weak_boundary("Left","Wall")
fluid.set_weak_boundary("Top","Wall")
fluid.set_weak_boundary("Right","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())
#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()))
    #Contact solver
    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))