The safe and efficient operation of locks is most relevant for the transport of goods on the waterways. One of the most important steps during the design process of a navigation lock is the dimensioning of the hydraulic system. There are concurrent requirements in this step, which have to be fulfilled: The construction and operation should be cheap, the filling process has to be as fast as possible and furthermore safety has to be guaranteed at any time by keeping the forces acting on the vessel within a certain range.
Typical approaches in literature can give an idea of the filling time and the forces which can be expected for through-the-head filling systems, but they often do not consider adequately the strongly transient character of the filling process. At the German Federal Waterways Engineering and Research Institute (BAW), traditionally a scaled laboratory model of the prototype is constructed and the forces acting on the vessel and the filling time are investigated. During the last years numerical methods have improved and approaches are available for the substitution of the laboratory model by complex numerical 3D models in some cases.
However, to give a preliminary estimation of the conditions during the lock filling process or to account for differences of the realized and designed geometry, maybe even years after the investigations have been carried out, it is not suitable to construct a new laboratory or a numerical model. Thus, the BAW developed a semi-implicit 1D numerical model which allows the simplified transient simulation of the lock filling process in a very short time with second order accuracy in time and space. Different valve types have been implemented to achieve a correct filling curve. This model allows the simple estimation of the longitudinal forces acting on the vessel.
In our contribution different methods to estimate the forces acting on a vessel during the lock filling process are discussed regarding effort and accuracy. Afterwards, the new numerical model will be described in detail. Validation experiments will be shown and first practical applications will be demonstrated. Finally, the authors will show how the numerical model can be used in hybrid modelling strategies to get better and more accurate results for more complex situations.