<div dir="ltr">      <br><span style="font-family:monospace,monospace">      include 'TSTEP' ! time, ifield<br>      include 'INPUT' ! cbc <br><br><br>      if (ifield .eq. 1 .and. time .gt. T) then<br>         nface = 2*ndim                                                                                                                                                                     <br>         do iel=1,nelv                                                                                                                                                                      <br>            do ifc=1,nface      <br>               if ("face belongs to part B") then   ! You need to identify your boundary B here<br>                  cbc (ifc,iel,ifld) = 'O  ' ! or 'o  ' or 'on ' or 'ON ' depending on what you need there<br>               endif                                                                                                                                                                        <br>            enddo                                                                                                                                                                           <br>         enddo    <br>      endif</span><br><br>On Wed, Apr 11, 2018 at 2:08 PM,  <<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>> wrote:<br>> Hi Neks,<br>><br>><br>> I wonder if it is possible to have boundary conditions that chage type with<br>> time?<br>><br>><br>> I want to simulate a flow where I make a 'puff' of fluid through a hole in a<br>> wall.<br>><br>> After the puff is made it continues to evolve without beeing forced.<br>><br>><br>> Mathematically, this is what I want:<br>><br>> Dirichlet boundary conditions (ux,uy,uz) = (0,0,1) for the velocity at a<br>> part B of the boundary up to a time T.<br>> Open boundary condition for the velocity at B for time > T.<br>><br>><br>> Is this possible to implement?<br>><br>><br>> Best,<br>><br>><br>> Johan<br>><br>><br>><br>> _______________________________________________<br>> Nek5000-users mailing list<br>> <a href="mailto:Nek5000-users@lists.mcs.anl.gov">Nek5000-users@lists.mcs.anl.gov</a><br>> <a href="https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users">https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users</a><br>></div>