Simulation Methods of Inner Flow Field and Flow Characteristics Induced by Perforated Reef-Type Breakwater

Abstract:

Based on flume experiment and numerical simulation， a refined study on 3D flow induced by a reef-type submerged breakwater was conduced to observe the turbulence performance and hydrodynamic characteristics in uniform inflow. Particle image velocimetry （PIV） is experimentally employed to successfully capture the three-dimensional vortex structure inside and outside the reef and a continuous vortex structure with transverse symmetry in the time-average flow field， which reveals the ambient water exchange mechanism promoted by perforation of reef-type breakwaters. Further， a 3D numerical model with the same specifications of the PIV experiment is built using the finite volume method. An evaluation of the most frequently typically used four turbulence models， i.e. standard k-ε， renormalization group k-ε， realizable k-ε and large eddy simulation （LES）， on the flow field in vicinity of the perforated reef-type breakwater reef is presented. The results show that the inner flow separation predicted by LES is the most accurate due to the advantage of LES for directly solving the large eddy in the Navior-Stokes equation. However， the computational efficiency of the model is the lowest. The velocity and vortex structure near the reef block captured by realizable k-ε approximates the PIV flow visualization， and the computational efficiency is the highest， which is the most suitable turbulence model for the limited computed hardware equipment.

Key words:reef-type breakwater;detour flow;eddy structure;particle image velocimetry(PIV);turbulence model