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# Title: Atomisation of a pulsed liquid jet
#
# Description:
#
# A dense cylindrical liquid jet is injected into a stagnant lighter
# phase (density ratio 1/27.84). The inflow velocity is modulated
# sinusoidally to promote the growth of primary shear
# instabilities. Surface tension is included and ultimately controls
# the characteristic scale of the smallest droplets.
#
# Animations \ref{jet} and \ref{back} illustrate the atomisation process
# from two different view points.
#
# \begin{figure}[htbp]
# \caption{\label{jet}Atomisation of a pulsed liquid jet.}
# \begin{center}
# \video{atomisation/jet}{640}{480}
# \end{center}
# \end{figure}
#
# \begin{figure}[htbp]
# \caption{\label{back}Atomisation of a pulsed liquid jet.}
# \begin{center}
# \video{atomisation/back}{640}{480}
# \end{center}
# \end{figure}
#
# The simulation and visualisation are computed in parallel on 4
# processors. Dynamic load-balancing is used to distribute the charge
# between the processors (Figure \ref{balance}).
#
# \begin{figure}[htbp]
# \caption{\label{balance}Number of cells per processor as a
# function of time illustrating the effect of dynamic load-balancing.}
# \begin{center}
# \includegraphics[width=0.8\hsize]{balance.eps}
# \end{center}
# \end{figure}
#
# Author: St\'ephane Popinet
# Command: sh atomisation.sh
# Version: 100715
# Required files: atomisation.sh jet.gfv back.gfv
# Running time: 2 days on 4 processors
# Generated files: jet.ogv back.ogv jet.eps jet.png back.eps back.png balance.eps
3 2 GfsSimulation GfsBox GfsGEdge {} {
Global {
#define radius 1./12.
#define length 0.025
#define level 9
#define Re 5800
#define R2(y,z) ((y)*(y) + (z)*(z))
#define rho(T) (T + 1./27.84*(1. - T))
/* Weber = rhoV^2D/sigma = 5555 */
}
Time { end = 1.6 }
# Initial refinement of the inlet
Refine (x < -0.5 + length && R2(y,z) < 2.*radius*radius ? level : 5)
# Define a static field used to enforce the boundary conditions
# for volume fraction corresponding to a cylindrical jet
Variable T0
InitFraction T0 (radius*radius - R2(y,z))
VariableTracerVOF T
VariableCurvature K T Kmax
SourceTension T 0.00003 K
SourceViscosity 2.*radius/Re*rho(T)
PhysicalParams { alpha = 1./rho(T) }
# Use constant (maximum) resolution on the interface
AdaptFunction { istep = 1 } {
minlevel = 0
maxlevel = level
} (T > 0 && T < 1)
# Initialise a short jet
Init {} {
T = (x < -0.5 + length ? T0 : 0)
U = T
}
# Dynamic load-balancing
EventBalance { istep = 1 } 0.1
OutputTime { istep = 1 } log
OutputBalance { istep = 1 } log
OutputProjectionStats { istep = 1 } log
OutputTiming { istep = 100 } log
# Use the gfsview module to generate movies on-the-fly and in parallel
GModule gfsview
OutputView { step = 4e-3 } { ppm2theora -s 640x480 > jet.ogv } {
format = PPM width = 1280 height = 960
} jet.gfv
OutputView { step = 4e-3 } { ppm2theora -s 640x480 > back.ogv } {
format = PPM width = 1280 height = 960
} back.gfv
# Save a (single) snapshot every 100 timesteps
EventScript { istep = 100 } { rm -f snapshot-*.gfs }
OutputSimulation { istep = 100 } snapshot-%ld.gfs { }
# Generate figures
OutputView { start = end } jet.ppm { format = PPM width = 1280 height = 960 } jet.gfv
OutputView { start = end } back.ppm { format = PPM width = 1280 height = 960 } back.gfv
EventScript { start = end } {
for f in jet back; do
convert $f.ppm -geometry 640x480 $f.png
convert $f.png $f.eps
rm -f $f.ppm
done
awk '{if ($1 == "step:") t = $4;
else if ($1 == "domain") print t,$3,$5,$9;}' < log > balance
cat <<EOF | gnuplot
set term postscript eps color lw 2 20 solid
set output 'balance.eps'
set xlabel 'Time'
set ylabel 'Number of cells per processor'
plot [0:1.6]'balance' u 1:2 w l t 'Minimum', \
'balance' u 1:3 w l t 'Average', \
'balance' u 1:4 w l t 'Maximum'
EOF
}
}
GfsBox { pid = 0
top = Boundary
bottom = Boundary
back = Boundary
front = Boundary
left = Boundary {
# Pulsed jet on inflow
BcDirichlet U T0*(1. + 0.05*sin (10.*2.*M_PI*t))
BcDirichlet T T0
BcDirichlet V 0
BcDirichlet W 0
}
}
GfsBox { pid = 0
top = Boundary
bottom = Boundary
back = Boundary
front = Boundary
}
GfsBox { pid = 1
top = Boundary
bottom = Boundary
back = Boundary
front = Boundary
right = BoundaryOutflow
}
1 2 right
2 3 right
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