Bottom changes in coastal areas with complex shorelines

A model for the sea-bottom change simulations in coastal areas with complex shorelines is proposed. In deep and intermediate water depths, the hydrodynamic quantities are calculated by numerically integrating the contravariant Boussinesq equations, devoid of Christoffel symbols. In the surf zone, the propagation of the breaking waves is simulated by the nonlinear shallow water equations. The momentum equation is solved inside the turbulent boundary layer in order to calculate intrawave hydrodynamic quantities. An integral formulation for the contravariant suspended sediment advection-diffusion equation is proposed and used for the sea-bottom dynamic simulations. The proposed model is applied to the real case study of Pescara harbor (in Italy)

Numerical simulation of bed evolution dynamics: the Pescara harbor

A two-dimensional phase resolving model is used for the computation of the hydrodynamic field in wave-current interaction in the sea regions opposite to the Pescara harbor. The total sediment transport is given by the contribution of the suspended sediment load, calculated by solving the advection-diffusion equation for the suspended sediment concentration, and of the spatial variation of the bed load transport. The proposed model has been used to simulate the silting phenomenon occurring in the sea region opposite to the Pescara harbor in presence of coastal defense structures

Contravariant Boussinesq equations for the simulation of wave transformation, breaking and run-up

We propose an integral form of the fully non-linear Boussinesq equations in contravariant formulation, in which Christoffel symbols are avoided, in order to simulate wave transformation phenomena, wave breaking and near shore currents in computational domains representing the complex morphology of real coastal regions. The motion equations retain the term related to the approximation to the second order of the vertical vorticity. A new Upwind Weighted Essentially Non-Oscillatory scheme for the solution of the fully non- linear Boussinesq equations on generalised curvilinear coordinate systems is proposed. The equations are rearranged in order to solve them by a high resolution hybrid finite volume–finite difference scheme. The conservative part of the above-mentioned equations, consisting of the convective terms and the terms related to the free surface elevation, is discretised by a high-order shock- capturing finite volume scheme; dispersive terms and the term related to the approximation to the second order of the vertical vorticity are discretised by a cell-centred finite difference scheme. The shock-capturing method makes it possible to intrinsically model the wave breaking, therefore no additional terms are needed to take into account the breaking related energy dissipation in the surf zone. The model is applied on a real case regarding the simulation of wave fields and nearshore currents in the coastal region opposite Pescara harbour (Italy)

Modeling bed evolution using weakly coupled phase-resolving wave model and wave-averaged sediment transport model

In this paper, we propose a model for the simulation of the bed evolution dynamics in coastal regions characterized by articulated morphologies. An integral form of the fully nonlinear Boussinesq equations in contravariant formulation, in which Christoffel symbols are absent, is proposed in order to simulate hydrodynamic fields from deep water up to just seaward of the surf zones. Breaking wave propagation in the surf zone is simulated by integrating the nonlinear shallow water equations with a high-order shock-capturing scheme. The near-bed instantaneous flow velocity and the intra-wave hydrodynamic quantities are calculated by the momentum equation integrated over the turbulent boundary layer. The bed evolution dynamics is calculated starting from the contravariant formulation of the advection-diffusion equation for the suspended sediment concentration in which the advective sediment transport terms are formulated according to a quasi-three-dimensional approach, and taking into account the contribution given by the spatial variation of the bed load transport. The model is validated against several tests by comparing numerical results with experimental data. The ability of the proposed model to represent the sediment transport phenomena in a morphologically articulated coastal region is verified by numerically simulating the long-term bed evolution in the coastal region opposite Pescara harbor (in Italy) and comparing numerical results with the field data

Numerical investigation of fluid-structure interaction for long-span bridge decks

IIn this work a simulation model of aeroelastic phenomena for long-span bridges is presented. By the proposed model the aerodynamic field and the structural motion are simulated simultaneously and in a coupled manner. The structure is represented as a bidimensional rigid body with two degrees of freedom, having mass per unit length and mass moment of inertia per unit length equal to those of the deck. The aerodynamic fields are simulated by numerically integrating the Arbitrary Lagrangian-Eulerian (ALE) formulated Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a finite volume scheme on moving grids which adapt themselves to the structural motion. The finite volume method is based on high order weighted essentially non-oscillatory (WENO) reconstructions. The time discretisation is performed by a five stage fourth order accurate strong stability preserving Runge-Kutta (SSPRK) method. The URANS equations are completed by the turbulent closure relations which are expressed as a function of the turbulent kinetic energy and the turbulent frequency according to the k-omega SST approach. The model validation is performed by the comparison between numerical and experimental results. The proposed model is utilised in order to identify the flutter critical wind velocity of the Forth Road Bridge deck, and the numerical results are compared with those of an experimental campaign

A new numerical model for simulation of wave transformation, breaking and run-up in complex coastal regions

We propose an integral form of the fully non-linear Boussinesq equations in contravariant formulation, in which Christoffel symbols are avoided, in order to simulate wave transformation phenomena, wave breaking and near shore currents in computational domains representing the complex morphology of real coastal regions. Following the approach proposed by Chen (2006), the motion equations retain the term related to the approximation to the second order of the vertical vorticity. A new Upwind Weighted Essentially Non-Oscillatory scheme for the solution of the fully non-linear Boussinesq equations on generalised curvilinear coordinate systems is proposed. The equations are rearranged in order to solve them by a high resolution hybrid finite volume–finite difference scheme. The conservative part of the above- mentioned equations, consisting of the convective terms and the terms related to the free surface elevation, is discretised by a high-order shock-capturing finite volume scheme; dispersive terms and the term related to the approximation to the second order of the vertical vorticity are discretised by a cell-centred finite difference scheme. The shock-capturing method makes it possible to intrinsically model the wave breaking, therefore no additional terms are needed to take into account the breaking related energy dissipation in the surf zone. The model is verified against several benchmark tests, and the results are compared with experimental, theoretical and alternative numerical solutions