# Free surface boundary condition in the VOF metod

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 February 9, 2011, 13:33 Free surface boundary condition in the VOF metod #1 Member   Veskov Eugene Join Date: Feb 2011 Posts: 31 Rep Power: 15 I developed main VOF software basic on the SOLA-VOF, VOF-2D, but preesure do not convergence (breaking dam simulation) First variant main software based on the method artificial compressibility (pressure do not convergence), second variant based on the projection method (pressure do not convergence), divergence in emty cell adjacent to full cell is too high. Pressure and velocity boundary condition same as SOLA-VOF; SOLA-VOF, VOF-2D breaking dam simulation failed too.

 February 10, 2011, 00:16 #2 New Member   Cheng Zhang Join Date: Oct 2009 Posts: 11 Rep Power: 16 HI Ves If artificial compressibility is used in N-S equation, the pressure is no possibility to diverge if you write the program based on SOLA-VOF, so i think you need to check your program again. If the program above can run smoothly, the program based on project method can do so. Along

 March 8, 2011, 15:23 #3 Member   Veskov Eugene Join Date: Feb 2011 Posts: 31 Rep Power: 15 I am find some mistake in my programs, but they does not work. First program based on the Veldman's sample program, boundary condition for free surface pressure and velocities same as in SOLA-VOF. Second program based on the artifical compressibility. Solving equation: dU/dtau+dU/dt+grad(U^2)=-1/rho*gradP+F 1/beta*dP/dtau+divU=0; beta=1-relaxation parameter;-tau psevdotime; iteration: internal cycle tau while divU>eps, external cycle t. boundary condition for free surface pressure and velocities same as in SOLA-VOF. VOF in both program based on Hirt-Nichols local-height function or free surface normal. Navier-Stokes good work (shear cavity), VOF good work (Zalesyak test), Navier-Stokes +VOF+free surface boundary condition does not work. Why? Help, please.