SIMULATION OF LOCAL SCOURING AROUND BRIDGE PILE AT BENDING CHANNEL WITH FVCOM MODEL

• Main Author: HERDIANSYAH - NIM: 25016037, SONY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31033
• Institution: Institut Teknologi Bandung

<p align="justify">Water is the most important commodity and sustainer for the survival of human life on earth. However, in addition to having benefits, water also has the potential for damaged power. One potential of water damage is scouring. Scouring due to water flow can occur in many conditions. One of the conditions that causes scouring is the presence of bridge pile on the water flow. In addition, scouring can also occur in the channel bend. In this study a local scour around the bridge pile at bending channel simulated with FVCOM numerical model using finite volume method to solve the derivative Navier-Stokes primitive equations for free surface flow, the Exner mass conservation equation for bed morphology, the evolution equation for the concentration of the suspended sediments, and the Meyer-Peter and Muller empirical equations for bed sediment flux. <br /> <br /> <br /> Prior to the local scour around the bridge pile at bending channel simulation, FVCOM model simulations for simpler cases are performed to observe FVCOM capability in capturing phenomena occurring in local scouring cases around the bridge pillar on the channel bend. The cases simulated in this study are tidal hydrodynamics, hydrodynamic at river bend, hydrodynamics of hypothetical bay and island, suspended sediment transport, local scouring around the bridge pile on a straight channel, and scouring around the bridge pile on the channel bend. The simulation results are then verified and calibrated against analytical solutions, experimental results, or numerical simulations in the previous study. The reference value for comparison is the Pearson correlation and the error rate. Pearson's correlation illustrates the suitability of trends between the simulation results and the reference values, while the error rate represents the difference between the simulated results and the reference values. <br /> <br /> <br /> Tidal hydrodynamic simulations resulted in 96.1 percent of Pearson correlation and a 6.1 percent of error rate for time-series water levels against the results of analytical solutions. The simulation of the suspended sediment transport resulted in 99.8 percent of Pearson correlation and 1.18 percent of error rate for the vertical profile of the suspended sediment concentration against the ROMS model simulation results. In the hydrodynamic simulation of the bend channel, no quantification of Pearson correlation and error rate was obtained, but it can be concluded that FVCOM succeeded in capturing the secondary flow phenomenon, tangential velocity distribution, and superelevation of the water level in the channel bend. In the hydrodynamic simulation of hypothetical bay and island cases, FVCOM succeeded in capturing the phenomenon of current around the island. Local scour simulations around the bridge pile on a straight channel resulted in 98.99 percent of Pearson correlation and a 5.96 of percent error rate for the timeseries of scouring against the experimental results in the previous study. In the case of local scours around the bridge pile on a straight channel, FVCOM capability is also seen in capturing and simulating downward flow phenomena in the upstream of the pile, vertical vortex occurring in the upstream of the pile near bed, and horizontal flow vortex downstream of the pile. From the simulation results, it can be concluded that FVCOM succeeded in capturing downward flow and horizontal vortex, but failed in capturing vertical vortex phenomenon. <br /> <br /> <br /> The results show that the common phenomenon that occurs in the channel bend and flow through the pillars can be simulated well by the FVCOM model. The location, magnitude, and time of the maximum scour are then compared between the numerical simulation results and the experimental results. From the results of the comparison, it can be assessed the reliability of the FVCOM model in simulating and predicting local scours around the bridge pile on the channel bend. <p align="justify">