Dear Sir, The equation is Poisson's equation with mixed boundary conditions. The domain is a cylinder shell. I am trying to apply Homogeneous Boundary Condition on the bottom face as done in step-18 and Neumann Boundary Condition on the inner surface of the cylinder. I have already derived a weak formulation of the equation and come up with the term you have mentioned. When applying in the code, do I have to construct a separate template for "pressure"? or can i just put the value explicitly in the cell_rhs component for Neumann boundary? And if I do the latter, what will be the direction of the pressure relative to the face?
Thank you. Himal On Thu, Nov 17, 2022 at 10:03 AM Wolfgang Bangerth <[email protected]> wrote: > On 11/16/22 03:58, HIMAL MAGAR wrote: > > I am trying to apply Neumann boundary condition(pressure) on inner wall > of a > > cylinder. So far, I have followed Lecture 21.55 to apply this condition > in 2d > > (in step-6 and step-8) and succeeded. But when it came to 3d case, I am > having > > hard time understanding how to implement pressure which is always normal > to > > the faces of inner wall. > > Himal: > the first step in these cases is always to write down the weak formulation > of > the equation. Can you explain what the equation is and where Neumann > boundary > conditions enter? There shouldn't really be a difference between 2d and > 3d, > you will generally just end up with a term of the form > (p, n.phi)_{Gamma_N} > where p is the prescribed pressure, n the normal vector, and phi a > (vector-valued) test function, all integrated over that part of the > boundary > Gamma_N where you impose Neumann boundary conditions. The form of this > integral does not depend on whether you are in 2d or 3d. > > Best > W> > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > www: http://www.math.colostate.edu/~bangerth/ > > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to a topic in the > Google Groups "deal.II User Group" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/dealii/_4eeywhhxk4/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/eb88ce6b-90bb-8dcc-c65b-6556f9f2b17c%40colostate.edu > . > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CA%2BNXOPpkO8LjB_4YJ4jRX2L9R%3DWKUdtmNQjV6kMc3anjwZ%2BMJw%40mail.gmail.com.
