Boundary conditions

General Discussion
1

Hi,
i have the following code and i want to add the boundary condition
dV/dx(L,t)=0, dV/dx(0,t)=0
and the initial conditions
U(x,0)=1, I(x,0)=0, V(x,0)=1
How we can do this please? I write some examples in FF++, i try some tentatives without results.
Thank you in advance.

load “msh3”

verbosity=1;

ofstream fout(“U.txt”);
ofstream fouti(“I.txt”);
ofstream foutou(“V.txt”);

real L=1.;

real k2=10.;

real k3=1.;

real D=0.001;

real sigma1=1.;

real sigma2=1.;

real x0=0.3;

int N=200.;

real t=0.0;

real dt=0.1;

real tau=1.0;

real n= tau/dt;

real a=0., b=1.;
mesh Th=square(n,1,[a+x*(b-a),y/10]);

fespace Vh(Th,[P1,P1]);

Vh [T1,T2,T3];

Vh[U,I,V];

\Initial conditions

Vh Uold=0.0;
Vh Iold=0.0;
Vh Vold=0.0;
real T=1000.0;// arbitraire
int[int] Order= [1];
string DataName;

\ Definition of Heaviside function

func real H (real s) {
if ( s <=0)
return 1;
else
return 0.0;
};

//Problem

problem system ([T1,T2,T3], [U,I,V])

int2D(Th)(UT1+IT2+VT3)
-int2D(Th)(UoldT1+IoldT2+VoldT3)
+int2D(Th)(k2UVT1dt) - int1D(Th)(k2UVT2dt)
+int2D(Th)(sigma1IT2dt)
+int2D(Th)(Ddx(V)dx(T3)dt)
-int2D(Th)(k3I(x,t-ndt)H(t-ndt)T3dt)
+int2D(Th)(sigma2VT3*dt)
;