Two-dimensional hydrofoil hydrodynamic performance and waveform evolution studies in density stratification and homogeneous fluid

This paper presents a numerical simulation study of the hydrodynamic coefficients, surrounding flow and generated internal waves of the NACA0012 hydrofoil in two-dimensional unsteady incompressible viscous stratified and uniform flows using computational fluid dynamics (CFD) methods. The Reynolds-averaged Navier-Stokes equations are discretized using the finite volume method (FVM) and combined with the volume of fluid (VOF) method to capture the interface between different phases. The k-ω SST turbulence model is used to predict the turbulent flow around the hydrofoil under different conditions. In order to validate the numerical methods, the simulation values are compared with the experimental results in this paper. The hydrodynamic coefficients and generated flow fields of hydrofoils in a stratified flow environment, i.e. water velocities, angles of attack, freshwater layer thicknesses, density differences and submergence depths are investigated. The surrounding flow fields and hydrodynamic characteristics of the hydrofoil in stratified flow are revealed by comparing the force coefficients and flow fields in homogeneous flow environment. The results show that compared to uniform flow, the hydrofoil can have a maximum loss of lift coefficient of 10.29% and a maximum reduction in drag coefficient of 49.1% in a stratified flow environment. Choosing the right variable can significantly improve the lift-to-drag ratio.