For a continuative outflow boundary, flow velocity is assumed to be continuous across the boundary. The u, v, and w velocity components at a boundary vertex are set equal to the average of those on the neighboring interior/fluid vertices. Usually, the flow direction is pointing outwards at an outflow boundary. However, under certain circumstances, reverse flow is possible and allowed. In this case, the species composition of the reverse flow is assumed to be the same as the initial species composition in the neighboring fluid region.

At the continuative outflow boundary, pressure in the ghost cell is assumed to be equal to the pressure in the interior neighboring fluid cell. For gas flows, density in the ghost cell is calculated using the isentropic relation (Equation 3–23), and the reference pressure () is set as the initial pressure of the neighboring region. For two-phase flows, density in the ghost cell is set equal to the density in the interior neighboring fluid cell.