Locks are key structures for the accessibility of ports and navigable waterways. The filling of the lock chamber has to be done with special precautions, taking into account the forces experienced by the moored vessels during the levelling process. In case of filling through lock gate openings, one of the potential methods to minimize the hydrodynamic forces on the ships, is to insert breaking logs at the downstream side of the gate openings, aiming at an enhanced spreading and energy dissipation of the filling jets.
To investigate the influence of the breaking log configuration on the induced flow patterns and their role in the energy dissipation of a turbulent filling jet, Flanders Hydraulics Research has defined a project in which both physical model research (phase 1) and Computational Fluid Dynamics (phase 2) are adopted .
This report pertains to phase 2 of the project and concerns the CFD modelling of the flow pattern in a lock chamber during lock filling. A model was set up of a schematic lock chamber with mitre gates. In the lock gates, in total six openings are present. Non-stationary simulations were performed using the volume of fluid method, to take the influence of the motion of the free surface into account. Different configurations of the opening geometry were investigated: one in which the openings are aligned perpendicular to the lock gate and one in which the openings are aligned with the lock chamber symmetry axis. For each of these configurations, the flow pattern in the lock chamber is modelled both for a configuration with and a configuration without breaking logs. Also the translation waves in the lock chamber are visualised. Additionally, for the configuration with the openings aligned with the channel axis and without breaking logs, the influence of closing the valves of all openings with 50 % was investigated in an additional simulation.
The simulations show that the influence of the geometry of the openings on the occurring flow patterns is relatively limited. Breaking logs on the other hand are shown to be effective in reducing the flow velocities in the lock chamber. At the same time, neither changes in the geometry of the opening nor the addition of breaking logs have a strong effect on the filling efficiency of the lock.