在 2017年10月16日星期一 UTC+2下午4:31:25，Wolfgang Bangerth写道： > > > > So when you visualize the solution, the error is at the boundary but > it looks > > correct in the interior? > > > > Yes, it is. Thereafter, the error at boundaries does propagate and then > > interfere with the interior. > > From the pictures you posted in a follow-up, it looks like the boundary > values are actually correct, but that the problem starts one layer of > cells > into the domain. Do I see this correctly? > > Yes, exactly. And if I use the BC values as 0, then it seems OK now (see figs below). What if I want to apply some value other than 0, this problem seems annoying.
> > > > Is there a simple way to update the RHS of old value using > something > > simple > > > like vmult? > > > > What is the equation you are trying to implement? > > > > I am trying just the Heat equation, > > rho * C * dT/dt = nabla *(kappba nalbaT) + f(x,y,t); > > Boundary condition is, > > T(x,y,z,t) = 300K, at boundaries. > I meant the "update the RHS of old value" equation. > > sorry, I mistook your idea. The RHS function is, f(x,y,z,t) = I0 * exp(-((x-v*t)^2 + (y-v*t)^2 +(z-v*t)^2)/2c^2), which stands for absorption of the laser. <https://lh3.googleusercontent.com/-YDAvb3f2jY0/WeTIKa5JdGI/AAAAAAAAADc/tTckR8bWK-AJ_JLDYA-yQ6kh_VPzxGFRQCLcBGAs/s1600/tem_BC0.gif> Boundary value = 0, initial values = 0 <https://lh3.googleusercontent.com/-YDAvb3f2jY0/WeTIKa5JdGI/AAAAAAAAADc/tTckR8bWK-AJ_JLDYA-yQ6kh_VPzxGFRQCLcBGAs/s1600/tem_BC0.gif> -- 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 dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
