Storing data for each timestep

Dear all

I solve unsteady navier-stokes equation in FF++ and I want to store velocities (u,v) in a matrix for one period and for each time step. is there anyway to write it?
For instance,
for (i=0; i<T/dt; i++)
Solve Ns;
store each u and v in a column of matrix for each time and regenerate the matrix
at the end we need this, U=[[u,v]@t1,[u,v]@t2,…[u,v]@T]

NO problem,

you can define e fespace Wh(Th,[Pk,Pk]) ; for example where Pkk is the finite element for for u and v;

Wh [int] [U1,U2](niter); // a array 
for (i=0; i<T/dt; i++)
Solve Ns;
  [U1[i],U2[i]] = [u,v]; // store u,v in  composante i.