Scale effects in free-surface flow modeling with turbulent regime via 3D Large Eddy Simulation (LES) technique

Abstract

This research was conducted using numerical simulation to investigate scale effect in hydraulic modeling, which can lead to differences between the results of the experiment and the real-world system, thus significantly affect the accuracy and reliability of physical modeling experiments. For this, OpenFOAM was utilized to investigate the scale effect, for which flow around submerged conical island as the model. Large Eddy Simulation (LES) was chosen due to its ability to solve and capture instantaneous movement in turbulent flow. The numerical simulations were conducted in two stages. The first phase was to verify whether the numerical model was in agreement with the experimental data. The second phase was to simulate upscaled model which was scaled using Froude similarity, in order to investigate scale effect, especially in the recirculating flow zone. Our results demonstrated that OpenFOAM was able to replicate the experimental data with a relatively low margin of error. Furthermore, the result showed that the scale effect appeared in the recirculating zone, in the form of either difference in velocity magnitude or difference in vortices period. However, for the nonrecirculating zone, the scale effects were not significant. This evidence proved our hypothesis that the scale effects due to the Froude similarity is quite significant when the recirculating turbulent flow occurs.