thermal.edp

FreeFem++可以生成高质量的有限元网格。可以用于流体力学

// file heatex.edp
int C1=99, C2=98; // could be anything
border C0(t=0,2*pi){x=5*cos(t); y=5*sin(t);}

border C11(t=0,1){ x=1+t;  y=3;      label=C1;}
border C12(t=0,1){ x=2;    y=3-6*t;  label=C1;}
border C13(t=0,1){ x=2-t;  y=-3;     label=C1;}
border C14(t=0,1){ x=1;    y=-3+6*t; label=C1;}

border C21(t=0,1){ x=-2+t; y=3;      label=C2;}
border C22(t=0,1){ x=-1;   y=3-6*t;  label=C2;}
border C23(t=0,1){ x=-1-t; y=-3;     label=C2;}
border C24(t=0,1){ x=-2;   y=-3+6*t; label=C2;}

mesh Th=buildmesh(    C0(50)
                    + C11(5)+C12(20)+C13(5)+C14(20)
                    + C21(-5)+C22(-20)+C23(-5)+C24(-20));
plot(Th,wait=1);

fespace Vh(Th,P1); Vh u,v;
Vh kappa=1+4*(x<-1)*(x>-2)*(y<3)*(y>-3);
solve a(u,v)= int2d(Th)(kappa*(dx(u)*dx(v)+dy(u)*dy(v)))
                +on(C0,u=20)+on(C1,u=100);
plot(u,value=true,wait=1,fill=true);