Dirk Rijnsdorp - Academia.edu (original) (raw)

Papers by Dirk Rijnsdorp

Research paper thumbnail of Simulating waves and their interactions with a restrained ship using a non-hydrostatic wave-flow model

Coastal Engineering, 2016

Research paper thumbnail of Numerical modelling of interactions between non-hydrostatic free-surface flows and a non-moving floating body

In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating inte... more In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating interactions between free-surface flows and a non-moving floating body. The proposed numerical model is validated for the wave transformation around a non-moving box-shaped body. Numerical results are compared with a semi-analytical solution and a laboratory experiment. These demonstrate that the proposed numerical model, despite the fact that it does not fully resolve the complex three-dimensional flow patterns near the body, describes the wave transformation well around a box-shaped body.

Research paper thumbnail of Infragravity-wave dynamics in a barred coastal region, a numerical study

Journal of Geophysical Research: Oceans, 2015

This paper presents a comprehensive numerical study into the infragravity-wave dynamics at a fiel... more This paper presents a comprehensive numerical study into the infragravity-wave dynamics at a field site, characterised by a gently-sloping barred beach. The non-hydrostatic wave-flow model SWASH was used to simulate the local wave field for a range of wave conditions (including mild and storm conditions). The extensive spatial coverage of the model allowed us to analyse the infragravity-wave dynamics at spatial scales not often covered before. Overall, the model predicted a wave field that was representative of the natural conditions, supporting the model application to analyse the wave dynamics. The infragravity-wave field was typically dominated by leaky waves, except near the outer bar where bar-trapped edge waves were observed. Relative contributions of bar-trapped waves peaked during mild conditions, when they explained up to 50% of the infragravity variance. Near the outer bar, the infragravity wave growth was partly explained by nonlinear energy transfers from short-waves. This growth was strongest for mild conditions, and decreased for more energetic conditions when short-waves were breaking at the outer bar. Further shoreward, infragravity waves lost most of their energy, due to a combination of nonlinear transfers, bottom friction, and infragravitywave breaking. Nonlinear transfers were only effective near the inner bar, whereas near the shoreline (where losses were strongest) the dissipation was caused by the combined effect of bottom friction and breaking. This study demonstrated the model's potential to study wave dynamics at field scales not easily covered by in-situ observations. Second, infragravity waves can break and lose most of their energy in a region close to the shore [van Dongeren et al., 2007; de Bakker et al., 2014 de Bakker et al., , 2015. Third, infragravity waves can lose energy due to bottom friction, although this mechanism is mainly significant in the case of extensive shallow regions such as coral reefs Van Dongeren et al., 2013].

Research paper thumbnail of Numerical modelling of interactions between non-hydrostatic free-surface flows and a non-moving floating body

In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating inte... more In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating interactions between free-surface flows and a non-moving floating body. The proposed numerical model is validated for the wave transformation around a non-moving box-shaped body. Numerical results are compared with a semi-analytical solution and a laboratory experiment. These demonstrate that the proposed numerical model, despite the fact that it does not fully resolve the complex three-dimensional flow patterns near the body, describes the wave transformation well around a box-shaped body.

Research paper thumbnail of Non-hydrostatic modelling of infragravity waves under laboratory conditions

Coastal Engineering, 2014

The non-hydrostatic wave model SWASH is compared to flume observations of infragravity waves prop... more The non-hydrostatic wave model SWASH is compared to flume observations of infragravity waves propagating over a plane slope and barred beach. The experiments cover a range of infragravity wave conditions, including forcing by bichromatic and irregular waves, varying from strongly dissipative to strongly reflective, so that model performance can be assessed for a wide range of conditions. The predicted bulk wave parameters, such as wave height and mean wave period, are found to be in good agreement with the observations. Moreover, the model captures the observed breaking of infragravity waves. These results demonstrate that SWASH can be used to model the nearshore evolution of infragravity waves, including nonlinear interactions, dissipation and shoreline reflections.

Research paper thumbnail of Simulating waves and their interactions with a restrained ship using a non-hydrostatic wave-flow model

Coastal Engineering, 2016

Research paper thumbnail of Numerical modelling of interactions between non-hydrostatic free-surface flows and a non-moving floating body

In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating inte... more In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating interactions between free-surface flows and a non-moving floating body. The proposed numerical model is validated for the wave transformation around a non-moving box-shaped body. Numerical results are compared with a semi-analytical solution and a laboratory experiment. These demonstrate that the proposed numerical model, despite the fact that it does not fully resolve the complex three-dimensional flow patterns near the body, describes the wave transformation well around a box-shaped body.

Research paper thumbnail of Infragravity-wave dynamics in a barred coastal region, a numerical study

Journal of Geophysical Research: Oceans, 2015

This paper presents a comprehensive numerical study into the infragravity-wave dynamics at a fiel... more This paper presents a comprehensive numerical study into the infragravity-wave dynamics at a field site, characterised by a gently-sloping barred beach. The non-hydrostatic wave-flow model SWASH was used to simulate the local wave field for a range of wave conditions (including mild and storm conditions). The extensive spatial coverage of the model allowed us to analyse the infragravity-wave dynamics at spatial scales not often covered before. Overall, the model predicted a wave field that was representative of the natural conditions, supporting the model application to analyse the wave dynamics. The infragravity-wave field was typically dominated by leaky waves, except near the outer bar where bar-trapped edge waves were observed. Relative contributions of bar-trapped waves peaked during mild conditions, when they explained up to 50% of the infragravity variance. Near the outer bar, the infragravity wave growth was partly explained by nonlinear energy transfers from short-waves. This growth was strongest for mild conditions, and decreased for more energetic conditions when short-waves were breaking at the outer bar. Further shoreward, infragravity waves lost most of their energy, due to a combination of nonlinear transfers, bottom friction, and infragravitywave breaking. Nonlinear transfers were only effective near the inner bar, whereas near the shoreline (where losses were strongest) the dissipation was caused by the combined effect of bottom friction and breaking. This study demonstrated the model's potential to study wave dynamics at field scales not easily covered by in-situ observations. Second, infragravity waves can break and lose most of their energy in a region close to the shore [van Dongeren et al., 2007; de Bakker et al., 2014 de Bakker et al., , 2015. Third, infragravity waves can lose energy due to bottom friction, although this mechanism is mainly significant in the case of extensive shallow regions such as coral reefs Van Dongeren et al., 2013].

Research paper thumbnail of Numerical modelling of interactions between non-hydrostatic free-surface flows and a non-moving floating body

In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating inte... more In this paper we present a depth-averaged semi-implicit non-hydrostatic model for simulating interactions between free-surface flows and a non-moving floating body. The proposed numerical model is validated for the wave transformation around a non-moving box-shaped body. Numerical results are compared with a semi-analytical solution and a laboratory experiment. These demonstrate that the proposed numerical model, despite the fact that it does not fully resolve the complex three-dimensional flow patterns near the body, describes the wave transformation well around a box-shaped body.

Research paper thumbnail of Non-hydrostatic modelling of infragravity waves under laboratory conditions

Coastal Engineering, 2014

The non-hydrostatic wave model SWASH is compared to flume observations of infragravity waves prop... more The non-hydrostatic wave model SWASH is compared to flume observations of infragravity waves propagating over a plane slope and barred beach. The experiments cover a range of infragravity wave conditions, including forcing by bichromatic and irregular waves, varying from strongly dissipative to strongly reflective, so that model performance can be assessed for a wide range of conditions. The predicted bulk wave parameters, such as wave height and mean wave period, are found to be in good agreement with the observations. Moreover, the model captures the observed breaking of infragravity waves. These results demonstrate that SWASH can be used to model the nearshore evolution of infragravity waves, including nonlinear interactions, dissipation and shoreline reflections.