A study of the flow field characteristics around star-shaped artificial reefs

In this paper, a three-dimensional numerical model is devised to calculate the unsteady flow field around star-shaped artificial reefs. The model is based on Reynolds-averaged Navier–Stokes (RANS) equations embedded within a renormalization group (RNG) k–ε turbulence model. The RANS equations are solved using the finite volume method (FVM) with an unstructured tetrahedral mesh. The pressure and velocity coupling is solved at each time step with the SIMPLEC algorithm. Non-invasive particle image velocimetry (PIV) laboratory measurements are employed to verify the simulation results. Good agreement is found between the simulation and experimental results with respect to the major flow fields. Based on the flow-field verification, the influence of arrangement and spacing on the flow field of one and two artificial reefs are discussed in light of the numerical method. A large-scale slow flow region is obtained when the reef is arranged in the second form. In the parallel combination, a slight mutual effect exists between the two reefs when the spacing is larger than 3.0L. In the streamwise combination, the interaction of two reefs is at its strongest at spacings of 3.0L to 4.0L.