/usr/share/doc/freefem++/examples/examples++/NSP1P1b.edp is in freefem++-doc 3.19.1-1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | // remark: the sign of p is correct
real s0=clock();
mesh Th=square(20,20);
Th=adaptmesh(Th,1./20.,IsMetric=1,splitpbedge=1);
fespace Vh2(Th,P1b);
fespace Vh(Th,P1);
Vh2 u2,v2,up1,up2;
Vh2 u1,v1;
Vh u1x=0,u1y,u2x,u2y, vv;
real reylnods=400;
//cout << " Enter the reynolds number :"; cin >> reylnods;
assert(reylnods>1 && reylnods < 100000);
up1=0;
up2=0;
func g=(x)*(1-x)*4;
Vh p=0,q;
real alpha=0;
real nu=1;
int i=0,iter=0;
real dt=0;
solve NS ([u1,u2,p],[v1,v2,q],solver=Crout,init=i) =
int2d(Th)(
alpha*( u1*v1 + u2*v2)
+ nu * ( dx(u1)*dx(v1) + dy(u1)*dy(v1)
+ dx(u2)*dx(v2) + dy(u2)*dy(v2) )
+ p*q*(0.000001)
- p*dx(v1) - p*dy(v2)
- dx(u1)*q - dy(u2)*q
)
+ int2d(Th) ( -alpha*convect([up1,up2],-dt,up1)*v1 -alpha*convect([up1,up2],-dt,up2)*v2 )
+ on(3,u1=g,u2=0)
+ on(1,2,4,u1=0,u2=0) ;
plot(coef=0.2,cmm=" [u1,u2] et p ",p,[u1,u2],ps="StokesP2P1.eps",value=1,wait=1);
{
real[int] xx(21),yy(21),pp(21);
for (int i=0;i<21;i++)
{
yy[i]=i/20.;
xx[i]=u1(0.5,i/20.);
pp[i]=p(i/20.,0.999);
}
cout << " " << yy << endl;
plot([xx,yy],wait=1,cmm="u1 x=0.5 cup");
plot([yy,pp],wait=1,cmm="pressure y=0.999 cup");
}
dt = 0.05;
int nbiter = 3;
real coefdt = 0.25^(1./nbiter);
real coefcut = 0.25^(1./nbiter) , cut=0.01;
real tol=0.5,coeftol = 0.5^(1./nbiter);
nu=1./reylnods;
for (iter=1;iter<=nbiter;iter++)
{
cout << " dt = " << dt << " ------------------------ " << endl;
alpha=1/dt;
for (i=0;i<=50;i++)
{
up1=u1;
up2=u2;
NS;
if ( !(i % 10))
plot(coef=0.2,cmm=" [u1,u2] et p ",p,[u1,u2],ps="plotNS_"+iter+"_"+i+".eps");
cout << "CPU " << clock()-s0 << "s " << endl;
}
if (iter>= nbiter) break;
Th=adaptmesh(Th,[dx(u1),dy(u1),dx(u1),dy(u2)],splitpbedge=1,abserror=0,cutoff=cut,err=tol, inquire=0,ratio=1.5,hmin=1./1000);
plot(Th,ps="ThNS.eps");
dt = dt*coefdt;
tol = tol *coeftol;
cut = cut *coefcut;
}
cout << "CPU " << clock()-s0 << "s " << endl;
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