Hello everybody. My problem is to find a way in order to impose a velocity field v = U + w x r
to a subdomains (a sphere) inside a cylindrical channel.
For what concern the translational velocity, U, no problem occurs following these step:
translation_x = Constant((1, 0, 0))
translation_y = Constant((0, 1, 0))
translation_z = Constant((0, 0, 1))
But for the angular velocity component I’m writing
rotation_x = Expression(("0", "x[1]-50", "-x[2]-50"))
rotation_y = Expression(("x[2]-50", "0", "-x[0]-50"))
rotation_z = Expression(("-x[1]-50", "x[0]-50", "0"))
These last three conditions coming from assuming the cross product between w (angular velocity) and r = 50 mm (distance from center of mass of the sphere). I don’t know if this can be right in order to reproduce a rotating sphere around the three axes . Many thanks