Boundary Conditions for The Navier-Stokes Equations
I try to solve 3D Navier-Stokes Equations. I set the model using the FEATool and export it as m-files on MATLAB. I want to change the symmetry/slip boundary conditions on m-files. I tried to change the symmetry/slip boundary condition, but the solutions did not change. How can change the boundary conditions on m-files?
Re: Boundary Conditions for The Navier-Stokes Equations
Thank you for your fast reply. I don't want to use no-slip, Symmetry/Slip, outflow, neutral outflow and inlet boundary conditions. How can I describe a new boundary condition in the GUI?
Unfortunately, there currently is no functionality to re-define or change boundary conditions in the GUI.
I tried to describe a new boundary condition in the m-files. Firstly, I set fea.phys.ns.bdr.sel as follows ...
It is also not possible to re-define boundary conditions using the physics modes (you can only use the defined ones).
The physics modes (here the Navier-Stokes physics mode defined in "fea.phys.ns") are used by the "parsephys" function to calculate the global (monolithic) weak equation and boundary contributions, that is the "fea.eqn" and "fea.bdr" are determined from the physics modes with the parsephys call.
fea.phys.ns = ... % select eqations coefficents and boundary conditions
fea = parsephys(fea); % > defines fea.eqn.(...) / fea.bdr.(...) from fea.phys.(...)
% assemble and solve using definitions in fea.eqn./fea.bdr
So if you want to define custom boundary conditions (or equations) you would change/modify the fea.bdr (or fea.eqn). For boundary conditions fea.bdr.d prescribes dirichlet coefficients and fea.bdr.n the Neumann/flux condition (if a Dirichlet condition is not prescribed). See the following page for definition of the boundary struct