A fast water slide layout approach using smooth surfaces, Saint Venant’s stationary water-streamline and passenger sliding interaction - Theory, implementation and validation

Water slide manufacturers are constantly searching for innovative designs that maximize the rider’s fun while complying with safety requirements. However, the current state-of-the-art does not offer any simulation tool capable of aiding the design phase before manufacture in an affordable computational time. This paper presents a novel approach using smooth surface models together with Saint Venant’s filament theory to predict the water channel and by this a realistic estimation of passenger - waterslide interaction. The model is applied to circular slide cross sections but can be extended to general surfaces. The paper covers the theory and the experimental validation. It is shown that the predicted water channel follows very well the measurement, and that the Saint Venant’s terms taking into consideration water channel heights and deformation of water cross-section play a marginal role and thus can be neglected, allowing one to use a simple Bernoulli filament model with proper water slide friction parameters. On the other hand, parameter identification of fluid-surface friction shows that three terms must be considered: a static one, a curvature-dependent correction, and a third correction factor for changes from low to large curvature (splashing effect). The results are also compared with fluid simulations using OpenFOAM. It is shown that the results of the simple model are not less accurate than the fluid-dynamics model, while needing only 1/100.000 of the computational time. The paper shows also the passenger/slide interaction by a multibody model including contact and passenger/fluid interactions. It is shown that the interaction between the passenger and the water is significant for correct reproduction of real motion, showing that the water channel is relevant for computer-based water slide layouts. As the water channel parameters can be sufficiently modeled by Bernoulli’s filament theory, the approach is independent of the slide cross section and thus extendable to general cases. Also, as the computations run at 7/10 of real time, they can be used for online optimizations and passenger-specific actions on site.