Understanding the flow behaviour of the tip vortex around hydrofoils, the corresponding pressure distribution and generated tip vortices are the key factors for prediction of cavitation inception and acoustic noise generation. Accordingly, numerical simulation of tip vortex flow generated around a National Advisory Committee for Aeronautics' hydrofoil (NACA 0015) is hereby investigated in the present study. To this end, the commercial software Ansys-CFX is applied, and Navier-Stokes equations are solved. Numerical simulations are performed using k-ω Shear Stress Transport (SST) model turbulence model. Validity of the solution is examined by comparing the obtained results against available experimental data for pressure coefficient distribution and lift coefficient (CL). Moreover, the lift and drag coefficients are computed and presented at different angles of attack. The velocity vector fields along with generated tip vortices are also presented. Two different vortices are observed, which are combined in the neighbourhood of trailing edge. On the other hand, the pressure distribution at the tip section is reported and effects of tip vortex on pressure variations are displayed and analysed. Ultimately, the streamlines are illustrated, and flow behaviour in the tip area and at the wake of the NACA hydrofoil is investigated.

The present paper focuses on the simulation of vortex-induced vibration (VIV) of a rigid, smooth circular cylinder with elastic supports subject to a cross-flow at the subcritical regime of Reynolds number, 30,000< Re<80,000. The circular cylinder is allowed to move in one degree-of-freedom (DOF), heave. Unsteady Reynolds-averaged Navier-Stokes (URANS) equations are solved with Menter’s k — [Formula: see text] based Shear Stress Transport based Scale-Adaptive Simulation, SAS-SST, turbulence model, and two-equation transition transport γ — θ model. The transport equations are discretized using the Finite Volume Method (FVM). The numerical amplitude and frequency ratio is compared against the experiments conducted in the Marine Renewable Energy Laboratory (MRELab) at the University of Michigan. The angle in which the computed lift leads the displacement in VIV is compared against experimental results reported by Cornell-ONR Water Channel as well. The existence of the initial, upper, and lower VIV response branches is demonstrated. Wake vortex pattern mode has been studied in the different branches of VIV. The time records of the added mass force coefficient and the vortex force coefficient are obtained. Then, the time-averaged phase angle of the vortex and added mass force coefficients are compared against the experimental results. Lastly, the time records of the phase angle in different branches of VIV are shown and analyzed.

There is currently a significant focus on using boundary layer control (BLC) approach for controlling the flow around bodies, especially the foil sections. In marine engineering this is done with the hope of increasing the lift -to -drag ratio and efficiency of the hydrofoils. In this paper, effects of the method on hydrodynamic characteristics and tip vortex formation of a hydrofoil are studied. Steady water injection at the tip of the hydrofoil is simulated in different conditions by using ANSYS-CFX commercial software. Validity of the proposed simulations is verified by comparing the obtained results against available experimental data. Effects of the injection on the lift, drag, and lift -to -dragratio are studied and the ranges within which the injection has the most positive or negative effects, are determined. Furthermore, flow pattern and pressure variation are studied upon the water injection to determine the most positive and negative case and to ascertain the main reasons triggering these phenomena.