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shanchen.m
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shanchen.m
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%% periodic flow my version
clear all;
clc;
% Macroscopic density and velocities
NX=128;
NY=128;
NPOP=9;
NSTEPS=300;
NOUTPUT=10;
% Parameters of the Shan-Chen model
rho_crit=log(2)
rho_liq=1.95
rho_gas=0.15
radius=20
G=-5.0
% Initialization
rho=ones(NX,NY);
ux=zeros(NX,NY);
uy=zeros(NX,NY);
feq=zeros(NPOP);
f1=zeros(NPOP,NX,NY);
f2=zeros(NPOP,NX,NY);
forcex=zeros(NX,NY);
forcey=zeros(NY,NY);
% Parameters of the lattice
weights=[4/9 1/9 1/9 1/9 1/9 1/36 1/36 1/36 1/36];
cx=[0 1 0 -1 0 1 -1 -1 1];
cy=[0 0 1 0 -1 1 1 -1 -1];
omega=1.0;
for y=1:NY
for x=1:NX
%if (x-NX/2)^2+(y-NY/2)^2<=radius*radius
% rho(x,y)=rho_liq;
%else
% rho(x,y)=rho_gas;
%end
rho(x,y)=rho_crit+0.1*rand();
ux(x,y)=0;
uy(x,y)=0;
vx=ux(x,y);
vy=uy(x,y);
for k=1:NPOP
feq(k)=weights(k)*rho(x,y)*(1+3*(vx*cx(k)+vy*cy(k)) ...
+ 9/2*((cx(k)*cx(k)-1/3)*vx*vx+2*cx(k)*cy(k)*vx*vy+(cy(k)*cy(k)-1/3)*vy*vy));
f1(k,x,y)=feq(k);
f2(k,x,y)=feq(k);
end
end
end
counter_frame=1;
for counter=1:NSTEPS
% Calculation of the macroscopic quantities
for y=1:NY
for x=1:NX
dense=0;
vx=0;
vy=0;
for k=1:NPOP
dense=dense+f1(k,x,y);
vx=vx+cx(k)*f1(k,x,y);
vy=vy+cy(k)*f1(k,x,y);
end
rho(x,y)=dense;
ux(x,y)=vx/dense;
uy(x,y)=vy/dense;
end
end
% Calculation of the force
for y=1:NY
for x=1:NX
force_sum_x=0.0;
force_sum_y=0.0;
for k=2:NPOP
newx=1+mod(x-1+cx(k)+NX,NX);
newy=1+mod(y-1+cy(k)+NY,NY);
psi=1-exp(-rho(newx,newy));
force_sum_x=force_sum_x-G*weights(k)*psi*cx(k);
force_sum_y=force_sum_y-G*weights(k)*psi*cy(k);
end
forcex(x,y)=(1-exp(-rho(x,y)))*force_sum_x;
forcey(x,y)=(1-exp(-rho(x,y)))*force_sum_y;
end
end
% main loop
for y=1:NY
for x=1:NX
dense=rho(x,y);
vx=ux(x,y)+0.5*forcex(x,y)/dense;
vy=uy(x,y)+0.5*forcey(x,y)/dense;
for k=1:NPOP
feq(k)=weights(k)*dense*(1+3*(vx*cx(k)+vy*cy(k)) ...
+9/2*((cx(k)*cx(k)-1/3)*vx*vx+2*cx(k)*cy(k)*vx*vy+(cy(k)*cy(k)-1/3)*vy*vy));
forcepop=weights(k)*(1-0.5*omega)*((3*(cx(k)-vx)+9*cx(k)*(cx(k)*vx+cy(k)*vy))*forcex(x,y)...
+(3*(cy(k)-vy)+9*cy(k)*(cx(k)*vx+cy(k)*vy))*forcey(x,y));
newx=1+mod(x-1+cx(k)+NX,NX);
newy=1+mod(y-1+cy(k)+NY,NY);
f1(k,x,y)=f1(k,x,y)*(1-omega)+feq(k)*omega+forcepop;
f2(k,newx,newy)=f1(k,x,y);
end
end
end
f1=f2;
counter
if mod(counter,NOUTPUT)==0
%surf(rho);
imagesc(rho);
F(counter_frame) = getframe;
counter_frame=counter_frame+1;
end
end
movie(F,10)
disp('Rho_liq=')
disp(mean(mean(rho(NX/2-5:NX/2+5,NY/2-5:NY/2+5))))
disp('Rho_gas=')
disp(mean(mean(rho(1:10,1:10))))