ABSTRACT
In a general isothermal flow the primary unknowns include the pressure, p, and the components of the velocity vector, u, which are functions of the spatial coordinates and time. In problems involving an unknown boundary, such as a free surface or an interface, the location h of this boundary is usually determined by the kinematic equation. Other flow variables, such as the nine components of the stress tensor, the residence time, the streamlines, etc., can be evaluated a posteriori once the primary unknowns have been calculated.
