The hydrodynamics of the continuous-phase flow in stagewise extraction columns under turbulent conditions is studied. An approach for estimation of the boundary conditions needed for solving the turbulent flow equations is presented. It is based on using the experimental data and simulation results from a pilot plate column and from a hollow column without internals. The relations derived allow the determination of the boundary conditions of the stage open boundaries for turbulent regimes according to the stage geometry parameters (plate free area, interplate distance, column diameter) and of the dynamical parameters of the flow (Re number) as well.