Hi Pavan,
one example is this one:
...
class BCM_MonitoringTraction(OpenGeoSys.BoundaryCondition):
def getFlux(self, t, coords, primary_vars):
x, y, z = coords
pp_actual = primary_vars[0]
ux_actual = primary_vars[1]
uy_actual = primary_vars[2]
uy_target = ExternalDisplacement(x, t)
uy_diff = uy_actual - uy_target
if abs(uy_diff) > 1e-15:
print("WARNING: uy_diff = ", uy_diff)
value = 0.0
jacob = [0.0, 0.0, 0.0]
return (False, value, jacob)
...
It’s not complete in the sense that the Jacobian is all-zero. The Jacobian is the derivative of the returned flux (value in the example) w.r.t. all primary variables.
The first value True/False in return (False, value, jacob) specifies if a BC should be set at that location. You can use this value to switch between Dirichlet and Neumann BCs: A BoundaryCondition subclass can have both a getFlux() and a getDirichletBCValue() method. There are also examples for Dirichlet BCs in the script I mentioned.
I hope that helps.
Best regards,
Christoph