# Apply a Neumann boundary condition on a 3D cylinder domain

Dear all,

I'm working on a 3D cylinder domain (see figure 5 in [1] https:/

(1) perfect rough boundary for the top and bottom (no horizontal sliding), the top will move downwards to simulate the loading process;

(2) constant confining pressure for the side of the cylinder (here is the problem).

I'm using escript 4.2 and the following code to apply the boundary condition:

vel = -0.1e-3; confining=-4.e6;

ro=0.025; lz = 0.1; # sample dimension

mydomain = ReadGmsh(

x = mydomain.getX()

bx = FunctionOnBound

outsideBF = whereZero(

# Dirichlet BC, rough loading ends

Dbc = whereZero(

Vbc = whereZero(

# Neumann BC, constant lateral confining

Nbc = outsideBF*

From my results, the applied confining pressure is smaller than I expected (around -3.2e6 https:/

Is there any suggestions for me? Thanks in advance.

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