The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave mak...The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave making performance of the plunger using two-dimensional(2 D)CFD calculations for a range of nearly linear wave conditions and compare the results with both experimental measurements and linear potential flow theory.Three wedge-shaped profiles,all with the same submerged volume,are considered.Moreover,the generated waves are compared with the predictions of linear potential flow theory.The calculations are made using the commercial ANSYS FLUENT finite-volume code with dynamic meshes to solve the Navier-Stokes equations and the volume of fluid scheme to capture the air-water interface.Furthermore,the linear potential flow solution of Wu(J Hydraul Res 26:481-493,1988)is extended to consider an arbitrary profile and serve as a reference solution.The amplitude ratios of the generated waves predicted by the CFD calculations compare well with the predictions of linear potential flow theory for a simple wedge,indicating that viscous effects do not influence this ratio for small-amplitude motions in 2 D.By contrast,significant higher harmonic components are produced by larger amplitude motions.Also,the simple wedge is found to produce the smallest spurious higher harmonic content in the far-field wave.展开更多
For robust nonlinear wave simulation in a moving reference frame, we recast the free surface problem in Hamilton-Jacobi form and propose a Weighted Essentially Non-Oscillatory （WENO） scheme to automatically handle t...For robust nonlinear wave simulation in a moving reference frame, we recast the free surface problem in Hamilton-Jacobi form and propose a Weighted Essentially Non-Oscillatory （WENO） scheme to automatically handle the upwinding of the convective term. A new automatic procedure for deriving the linear WENO weights based on a Taylor series expansion is introduced. A simplified smoothness indicator is proposed and is shown to perform well. The scheme is combined with high-order explicit Runge-Kutta time integration and a dissipative Lax-Friedrichs-type flux to solve for nonlinear wave propagation in a moving frame of reference. The WENO scheme is robust and less dissipative than the equivalent order upwind-biased finite difference scheme for all ratios of frame of reference to wave propagation speed tested. This provides the basis for solving general nonlinear wave-structure interaction problems at forward speed.展开更多
文摘The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave making performance of the plunger using two-dimensional(2 D)CFD calculations for a range of nearly linear wave conditions and compare the results with both experimental measurements and linear potential flow theory.Three wedge-shaped profiles,all with the same submerged volume,are considered.Moreover,the generated waves are compared with the predictions of linear potential flow theory.The calculations are made using the commercial ANSYS FLUENT finite-volume code with dynamic meshes to solve the Navier-Stokes equations and the volume of fluid scheme to capture the air-water interface.Furthermore,the linear potential flow solution of Wu(J Hydraul Res 26:481-493,1988)is extended to consider an arbitrary profile and serve as a reference solution.The amplitude ratios of the generated waves predicted by the CFD calculations compare well with the predictions of linear potential flow theory for a simple wedge,indicating that viscous effects do not influence this ratio for small-amplitude motions in 2 D.By contrast,significant higher harmonic components are produced by larger amplitude motions.Also,the simple wedge is found to produce the smallest spurious higher harmonic content in the far-field wave.
文摘For robust nonlinear wave simulation in a moving reference frame, we recast the free surface problem in Hamilton-Jacobi form and propose a Weighted Essentially Non-Oscillatory （WENO） scheme to automatically handle the upwinding of the convective term. A new automatic procedure for deriving the linear WENO weights based on a Taylor series expansion is introduced. A simplified smoothness indicator is proposed and is shown to perform well. The scheme is combined with high-order explicit Runge-Kutta time integration and a dissipative Lax-Friedrichs-type flux to solve for nonlinear wave propagation in a moving frame of reference. The WENO scheme is robust and less dissipative than the equivalent order upwind-biased finite difference scheme for all ratios of frame of reference to wave propagation speed tested. This provides the basis for solving general nonlinear wave-structure interaction problems at forward speed.
