An open boundary condition for incompressible stratified flows

A novel outflow boundary condition for incompressible laminar wall-bounded flows

“…Finally, a reference case with exactly the same parameters except for the outlet condition was also run. For this reference simulation, the convective velocity was chosen to be the local velocity at the exit plane, so that the two terms of this boundary condition, derived from (1), are exactly included in the new condition (2). Note that several convective velocities were applied but as they were not as good as the local velocity, the results obtained are not presented here.…”

“…This exit condition is a solution to the linearised convective equation (Eq. (1)), where the convection velocity U c is chosen to be either the maximum streamwise velocity [8], the mean streamwise velocity at this plane [4,7] or the local velocity [2,5] and x is the streamwise direction:…”

Boundary Conditions for Finite Element Simulations of Convective Flows With Artificial Boundaries

“…In this case, the diffusion term does not vanish in the equation for the last node; however, two linearly dependent expressions are obtained in the second and third rows of the diffusion matrix that reflect the singularity of the system in the absence of convection, i.e., when u = 0. A Taylor series analysis shows that the third difference equation in equation (12) leads to where the diffusion term is in fact a central approximation to the second derivative at node x,. This term introduces a perturbation at the boundary and induces oscillations in the solution unless the problem is highly dominated by convection.…”

Dynamic analysis of an inflatable dam subjected to a flood

“…The local wave velocity, c is in the general case unknown. Some authors (Han et al 1983) suggested a numerical method of calculating c. In the present study, c is set equal to the phase velocity gh p 1 (unit depth and gravitational acceleration have been assumed). The numerical method used to apply Eq.…”