The simulation of the propagation and evolution of sea waves in coastal regions and their interac... more The simulation of the propagation and evolution of sea waves in coastal regions and their interaction with coastal structures is a very useful engineering tool in several problems of coastal and environmental engineering [...]
In this paper, the hydrodynamic and free surface elevation fields in breaking waves are simulated... more In this paper, the hydrodynamic and free surface elevation fields in breaking waves are simulated by solving the integral and contravariant forms of the three-dimensional Navier–Stokes equations that are expressed in a generalized time-dependent curvilinear coordinate system, in which the vertical coordinate moves by following the free surface. A new k−l turbulence model in contravariant form is proposed; in this model, the mixing length, l, is defined as a function of the maximum water surface elevation variation. A new original numerical scheme is proposed. The main element of originality of the numerical scheme consists of the proposal of a new fifth-order reconstruction technique for the point values of the conserved variables on the cell face. This technique, named in the paper as WTENO, allows the choice procedure of the reconstruction polynomials for the point values to be modified in a dynamic way.
A new three-dimensional high-order shock-capturing model for the numerical simulation of breaking... more A new three-dimensional high-order shock-capturing model for the numerical simulation of breaking waves is proposed. The proposed model is based on an integral contravariant form of the Navier–Stokes equations in a time-dependent generalized curvilinear coordinate system. Such an integral contravariant form of the equations of motion is numerically integrated by a new conservative numerical scheme that is based on three elements of originality: the time evolution of the state of the system is carried out using a predictor–corrector method in which exclusively the conserved variables are used; the point values of the conserved variables on the cell face of the computational grid are obtained using an original high-order reconstruction procedure called a wave-targeted essentially non-oscillatory scheme; the time evolution of the discontinuity on the cell faces is calculated using an exact Riemann solver. The proposed model is validated by numerically reproducing several experimental t...
This numerical study investigated the effects of a vegetation patch on the flow of a channel. The... more This numerical study investigated the effects of a vegetation patch on the flow of a channel. The numerical approach consisted of a CFD, 3-D model that applied the RANS equations to simulate the flow field, and the VOF model to represent the free surface. The patch altered the initial flow by inducing regions of reduced velocity in the patch wake (approximately 40% reduction), and regions of enhanced velocity around of the patch (approximately 16% increase), and these regions extended throughout the water depth. Also, the patch induced a small change of 3.83% in the water surface, in the streamwise direction.
ABSTRACT In this paper, we propose a system of numerical models for the compatibility assessment ... more ABSTRACT In this paper, we propose a system of numerical models for the compatibility assessment of reservoir sediment flushing and protection of downstream river environments. The model system is made up of two simulation models. The first model simulates soil erosion in watershed slopes and sediment transport in the tributary of the reservoir by means of a weighted essentially nonoscillatory (WENO) method, which is conservative and fourth-order accurate in space and time. The second model simulates velocity and suspended solid concentration fields in the reservoirs. This model is based on the three-dimensional (3D) numerical integration of motion and concentration equations, expressed in contravariant form on a generalized boundary-conforming curvilinear coordinate system by using a conservative and higher-order accurate numerical scheme. The proposed system of models is applied to the Pieve di Cadore (Veneto, Italy) reservoir and to its catchment area. By comparing suspended solid concentrations that are discharged through the bottom outlets during flushing operations with suspended solid concentrations in the main river during natural flooding, we perform an assessment of the compatibility between sediment flushing and the protection of the river ecosystem downstream
International Journal for Numerical Methods in Fluids, 2010
Page 1. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids (2010) ... more Page 1. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids (2010) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/fld.2392 Central WENO scheme ...
Proceedings of the Sixth International Symposium On Turbulence, Heat and Mass Transfer, 2009
In this paper the relation between the Noll formulation of the Principle of Material Frame-Indiff... more In this paper the relation between the Noll formulation of the Principle of Material Frame-Indifference and the Hutter & Joehnk formulation of the Principle of Turbulent Frame-Indifference in Large Eddy Simulation is revised; the definition of a new rule for the formulation of turbulent closure relations is proposed. In this paper we demonstrate the Euclidean form-invariance and frame-dependence of the transport equation of the generalised SGS viscous dissipation ε . New closure relations for the SGS viscous dissipation transport equation are proposed. The proposed closure relations allow the modeled balance equation of ε to respect the properties of Euclidean form-invariance and frame-dependence of the exact equation
The present- day Large Eddy Simulation models based on the Smagorinsky assumption and the drawbac... more The present- day Large Eddy Simulation models based on the Smagorinsky assumption and the drawbacks of the dynamic calcula-tion of the closure coefficient for the generalised subgrid scale turbulent stress tensor are presented. The relations between numerical scheme conservation property of mass, momentum and kinetic energy and the drawbacks of the dynamic Smagorinsky- type turbulence models are shown. A new turbulence model is proposed. The proposed model: a) is able to take into account the anisotropy of the turbulence; b) remove any balance assumption between the production and dissipation of sub-grid scale turbulent kinetic energy; c) is able to eliminate the numerical effects produced by the non conservation a priori of the resolved kinetic energy. New closure relations for the unknown terms of the subgrid scale viscous dissipation balance equation are proposed. The filtered momentum equations are solved by using a sixth order finite difference scheme. The proposed model is tes...
The simulation of the propagation and evolution of sea waves in coastal regions and their interac... more The simulation of the propagation and evolution of sea waves in coastal regions and their interaction with coastal structures is a very useful engineering tool in several problems of coastal and environmental engineering [...]
In this paper, the hydrodynamic and free surface elevation fields in breaking waves are simulated... more In this paper, the hydrodynamic and free surface elevation fields in breaking waves are simulated by solving the integral and contravariant forms of the three-dimensional Navier–Stokes equations that are expressed in a generalized time-dependent curvilinear coordinate system, in which the vertical coordinate moves by following the free surface. A new k−l turbulence model in contravariant form is proposed; in this model, the mixing length, l, is defined as a function of the maximum water surface elevation variation. A new original numerical scheme is proposed. The main element of originality of the numerical scheme consists of the proposal of a new fifth-order reconstruction technique for the point values of the conserved variables on the cell face. This technique, named in the paper as WTENO, allows the choice procedure of the reconstruction polynomials for the point values to be modified in a dynamic way.
A new three-dimensional high-order shock-capturing model for the numerical simulation of breaking... more A new three-dimensional high-order shock-capturing model for the numerical simulation of breaking waves is proposed. The proposed model is based on an integral contravariant form of the Navier–Stokes equations in a time-dependent generalized curvilinear coordinate system. Such an integral contravariant form of the equations of motion is numerically integrated by a new conservative numerical scheme that is based on three elements of originality: the time evolution of the state of the system is carried out using a predictor–corrector method in which exclusively the conserved variables are used; the point values of the conserved variables on the cell face of the computational grid are obtained using an original high-order reconstruction procedure called a wave-targeted essentially non-oscillatory scheme; the time evolution of the discontinuity on the cell faces is calculated using an exact Riemann solver. The proposed model is validated by numerically reproducing several experimental t...
This numerical study investigated the effects of a vegetation patch on the flow of a channel. The... more This numerical study investigated the effects of a vegetation patch on the flow of a channel. The numerical approach consisted of a CFD, 3-D model that applied the RANS equations to simulate the flow field, and the VOF model to represent the free surface. The patch altered the initial flow by inducing regions of reduced velocity in the patch wake (approximately 40% reduction), and regions of enhanced velocity around of the patch (approximately 16% increase), and these regions extended throughout the water depth. Also, the patch induced a small change of 3.83% in the water surface, in the streamwise direction.
ABSTRACT In this paper, we propose a system of numerical models for the compatibility assessment ... more ABSTRACT In this paper, we propose a system of numerical models for the compatibility assessment of reservoir sediment flushing and protection of downstream river environments. The model system is made up of two simulation models. The first model simulates soil erosion in watershed slopes and sediment transport in the tributary of the reservoir by means of a weighted essentially nonoscillatory (WENO) method, which is conservative and fourth-order accurate in space and time. The second model simulates velocity and suspended solid concentration fields in the reservoirs. This model is based on the three-dimensional (3D) numerical integration of motion and concentration equations, expressed in contravariant form on a generalized boundary-conforming curvilinear coordinate system by using a conservative and higher-order accurate numerical scheme. The proposed system of models is applied to the Pieve di Cadore (Veneto, Italy) reservoir and to its catchment area. By comparing suspended solid concentrations that are discharged through the bottom outlets during flushing operations with suspended solid concentrations in the main river during natural flooding, we perform an assessment of the compatibility between sediment flushing and the protection of the river ecosystem downstream
International Journal for Numerical Methods in Fluids, 2010
Page 1. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids (2010) ... more Page 1. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids (2010) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/fld.2392 Central WENO scheme ...
Proceedings of the Sixth International Symposium On Turbulence, Heat and Mass Transfer, 2009
In this paper the relation between the Noll formulation of the Principle of Material Frame-Indiff... more In this paper the relation between the Noll formulation of the Principle of Material Frame-Indifference and the Hutter & Joehnk formulation of the Principle of Turbulent Frame-Indifference in Large Eddy Simulation is revised; the definition of a new rule for the formulation of turbulent closure relations is proposed. In this paper we demonstrate the Euclidean form-invariance and frame-dependence of the transport equation of the generalised SGS viscous dissipation ε . New closure relations for the SGS viscous dissipation transport equation are proposed. The proposed closure relations allow the modeled balance equation of ε to respect the properties of Euclidean form-invariance and frame-dependence of the exact equation
The present- day Large Eddy Simulation models based on the Smagorinsky assumption and the drawbac... more The present- day Large Eddy Simulation models based on the Smagorinsky assumption and the drawbacks of the dynamic calcula-tion of the closure coefficient for the generalised subgrid scale turbulent stress tensor are presented. The relations between numerical scheme conservation property of mass, momentum and kinetic energy and the drawbacks of the dynamic Smagorinsky- type turbulence models are shown. A new turbulence model is proposed. The proposed model: a) is able to take into account the anisotropy of the turbulence; b) remove any balance assumption between the production and dissipation of sub-grid scale turbulent kinetic energy; c) is able to eliminate the numerical effects produced by the non conservation a priori of the resolved kinetic energy. New closure relations for the unknown terms of the subgrid scale viscous dissipation balance equation are proposed. The filtered momentum equations are solved by using a sixth order finite difference scheme. The proposed model is tes...
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