Dear Community Members,

I would like to ask for your help in merit to a recent problem I run up against.

I am trying to solve a boundary value problem defined over the square [0,pi] x [0,H], where H>0.

To define such a square I write:

`mesh Square=square(50,50,[x*pi,y*H]);`

The boundary condition is imposed along the edge of the square which is labelled as `1`

. When I run the code and export the solution `u`

in ParaView, I obtain the following result

The result is clearly consistent with the boundary condition I have imposed, since the solution is defined over a finite element space given over the mesh `Square`

, and such a solution vanishes along the edge [0,pi] x {0}.

I would like to see the displacement along a cylindrical surface having radius `R`

and height `H`

, obtained by transforming the mesh `Square`

as follows

`meshS cylinder=movemesh23(Square, transfo=[R*cos(x), R*sin(x), y]);`

and I then expect the solution to vanish along the cylinder arc corresponding to the side of the square having label `1`

.

However, this is not the case. When I incorporate the solution `u`

in the deformed mesh `cylinder`

via the command

`savevtk("myfile.vtu", cylinder, u);`

I obtain the following result

which is not consistent with the boundary conditions I would like to impose.

I cannot see why the result is inconsistent. Could you please help me understand what I did wrong?

Many thanks and best regards,

Paolo