Maria Clavero - Academia.edu (original) (raw)

Papers by Maria Clavero

Research paper thumbnail of Pressure Distributions on a Vertical Breakwater: Experimental

Coastal Engineering Proceedings, Feb 1, 2011

This work studies the horizontal and uplift pressure distributions over a caisson founded on poro... more This work studies the horizontal and uplift pressure distributions over a caisson founded on porous materials, and their dependence on the stone diameter and the height of the foundation. For this, tests at a wave flume with an idealized composite breakwater of rectangular section, varying the depth of the foundation of the caisson and the diameter of the stones, were carried on. Eight resistive gauges and eight pressures sensors were used to measure free surface elevations and horizontal and uplift pressure variation, respectively. Results show that: 1) there exist a "saturation" of the reflection coefficient for B/L>0.4, being B the width of the dike and L the wave length, 2) by using the total wave height measured at the toe of the dike in the analysis, the dispersion of the results is significantly reduced; 3) dimensionless run-up and pressures obtained using total wave height mainly depends on the reflection regime and on the relative height of the foundation; 4) maximum uplift and horizontal forces are not always in phase, and three regimes are identified depending on which force dominates; and 5) the relation between the dimensionless forces with the total wave height at the toe of the dike depends mainly on the reflection regime and on the relative foundation height.

Research paper thumbnail of Note on a real gas model for OWC performance

Renewable Energy, 2016

Oscillating water column (OWC) are devices for wave energy extraction equipped with turbines for ... more Oscillating water column (OWC) are devices for wave energy extraction equipped with turbines for energy conversion. The purpose of the present work is to study the thermodynamic of a real gas flow through the turbine and its differences with respect to the ideal gas hypothesis, with the final goal to be applied to OWC systems. The effect of moisture in the air chamber of the OWC entails variations on the atmospheric conditions near the turbine, modifying its performance and efficiency. In this work we study the influence of humid air in the performance of the turbine. Experimental work is carried out and a real gas model is asserted, in order to take a first approach to quantify the extent of influence of the airewater vapour mixture in the turbine performance. The application of a real gas model and the experimental study confirmed the deviations of the turbine performance from the expected values depending on flow rate, moisture and temperature.

Research paper thumbnail of Wave Reflection and Stability Evolution of S-Profile Breakwaters

Coastal Structures 2007 - Proceedings of the 5th Coastal Structures International Conference, CST07, 2009

Research paper thumbnail of Failure of Seabeds with a High Mud Content: An Experimental Study

Coastal Engineering Proceedings, 2014

Seabed instability has been cited as the cause of failure for a number of coastal structures in r... more Seabed instability has been cited as the cause of failure for a number of coastal structures in recent years, stimulating an interest in understanding the interaction between waves, marine structures and the seabed upon which they are built. A series of experimental tests were carried out in a wave flume at the Engineering Institute of the National University of Mexico, to investigate the failure of seabeds with a high mud content and the interaction of the seabed with a scaled structure (vertical breakwater) and regular waves (T = 0.6, 0.8 and 1.0 s; H = 6, 8 and 10 cm), through the analysis of pore pressure distribution. Three different materials were tested: 100, 90 and 85 % mud content, mixed with natural sand and water. Pore pressure build-up was registered in the tests with 85 % of mud content, and knowing that a buildup precedes soil liquefaction, failure may have occurred. But in these cases the maximum pressure in the tests did not exceed the critical value and no liquefaction was observed. For soils of 90 and 100 % mud content, the pore pressure shows a homogeneous vertical behaviour and only pore pressure falls were registered. This phenomenon may be attributed to the cohesion effect in the mud particles and to the consolidation process.

Research paper thumbnail of Experimental Verification of Mound Breakwater Built with an S-Profile

Coastal Engineering 2006 - Proceedings of the 30th International Conference, 2007

In this paper, laboratory data of breakwater damage, profile evolution and energy fluxes over an ... more In this paper, laboratory data of breakwater damage, profile evolution and energy fluxes over an homogeneous mound breakwater are presented and discussed. The experiments were done over two models, consisting on a mound breakwater composed of cubes of the same size, ...

Research paper thumbnail of Pressure Distributions on a Vertical Breakwater: Experimental

Coastal Engineering Proceedings, 2011

This work studies the horizontal and uplift pressure distributions over a caisson founded on poro... more This work studies the horizontal and uplift pressure distributions over a caisson founded on porous materials, and their dependence on the stone diameter and the height of the foundation. For this, tests at a wave flume with an idealized composite breakwater of rectangular section, varying the depth of the foundation of the caisson and the diameter of the stones, were carried on. Eight resistive gauges and eight pressures sensors were used to measure free surface elevations and horizontal and uplift pressure variation, respectively. Results show that: 1) there exist a "saturation" of the reflection coefficient for B/L>0.4, being B the width of the dike and L the wave length, 2) by using the total wave height measured at the toe of the dike in the analysis, the dispersion of the results is significantly reduced; 3) dimensionless run-up and pressures obtained using total wave height mainly depends on the reflection regime and on the relative height of the foundation; 4) maximum uplift and horizontal forces are not always in phase, and three regimes are identified depending on which force dominates; and 5) the relation between the dimensionless forces with the total wave height at the toe of the dike depends mainly on the reflection regime and on the relative foundation height.

Research paper thumbnail of Determinação de forças actuantes em quebra-mares verticais e mistos

Revista da Gestão Costeira Integrada, 2012

Research paper thumbnail of An Unified Design Method of Maritime Works Against Waves

Coastal Engineering Proceedings, 2012

This work studies the interaction of a composite breakwater and irregular waves as a function of ... more This work studies the interaction of a composite breakwater and irregular waves as a function of the breakwater geometry and wave characteristics. For this, tests in a flume wave were carried out. The model consisted of a composite breakwater with rectangular cross section and with the width, foundation depth and stone diameter varying in order to know their influence in the breakwater behavior. Results show that reflection coefficient increase with B/L (where B is the width of the dike and L is the wave length) until a maximum value (saturation point) from which it is constant or decreases slightly. Before this point, reflection coefficient depends on breakwater geometry and wave characteristics and when the dike reaches the saturation regime, it only depends on stone diameter or porosity. The value of the sea water elevation at the wall and the horizontal pressure depends on the reflection coefficient. Finally, the relationship between horizontal and vertical forces is linear depending on the reflection regime. This analysis shows that energy distribution is the main variable to know the structural behavior of a dike. Based on these results, a methodology to obtain the loads over the composite breakwater is proposed.

Research paper thumbnail of Forces and Subpressures on Non-Overtoppable Vertical Breakwaters

Coastal Structures 2011, 2012

ABSTRACT This paper presents an analysis of measured data of pressures and subpressures, as well ... more ABSTRACT This paper presents an analysis of measured data of pressures and subpressures, as well as horizontal and vertical forces exerted by waves on a non-overtopping vertical breakwater during storm events. The breakwater studied was the North Breakwater of the Port of Gijón (Spain). The forces were obtained by integrating the measured pressures from 17 sensors spread across the central body, the superstructure and the bottom of the caisson. The results show the influence of the distribution of energy flows on the pressure laws due to the wave-breakwater interaction. The maximum sea-level reference pressure is directly proportional to the free surface at that instant. The simultaneity of the maximum horizontal and vertical forces in a given sea state was also analyzed, concluding that these forces are not always in phase.

Research paper thumbnail of Experimental analysis of the coherent structures and turbulence past a hydrofoil in stalling condition beneath a water–air interface

European Journal of Mechanics - B/Fluids, 2014

Research paper thumbnail of Study of the turbulence in the air-side and water-side boundary layers in experimental laboratory wind induced surface waves

This study detailed the structure of turbulence in the air-side and water-side boundary lay... more This study detailed the structure of turbulence in the air-side and water-side boundary layers in wind­ induced surface waves. lnside the air boundary layer, the kurtosis is always greater than 3 (the value for nor­mal distribution) for both horizontal and vertical velocity fluctuations.The skewness for the horizontal veloc­ity is negative, but the skewness for the vertical velocity is always positive. On the water side, the kurtosis is always greater than 3, and the skewness is slightly negative for the horizontal velocity and slightly positive for the vertical velocity.The statistics of the angle between the instantaneous vertical fluctuation and the in­stantaneous horizontal velocity in the air is similar to those obtained over solid walls.Measurements in water show a large variance, and the peak is biased towards negative angles.In the quadrant analysis, the contribu­tion of quadrants Q2 and Q4 is dominant on both the air side and the water side.The non-dimensional relative contributions and the concentration match fairly well near the interface. Sweeps in the air side (belonging to quadrant Q4) act directly on the interface and exert pressure fluctuations, which, in addition to the tangential stress and form drag, lead to the growth of the waves. The water drops detached from the crest and accelerated by the wind can play a major role in transferring momentum and in enhancing the turbulence level in the water side.
On the air side, the Reynolds stress tensor's principal axes are not collinear with the strain rate tensor, and show an angle aa =-20° to-25°. On the water side, the angle is aa = -40° to-45°. The ratio be­tween the maximum and the minimum principal stresses is aolab =3 to 4 on the air side, and arJ ab=1.5 to 3 on the water side. In this respect, the air-side flow behaves like a classical boundary layer on a solid wall, while the water-side flow resembles a wake. The frequency of bursting on the water side in­ creases significantly along the flow, which can be attributed to micro-breaking effects - expected to be more frequent at larger fetches.

Research paper thumbnail of 3D flow measurements in regular breaking waves past a fixed submerged bar on an impermeable plane slope

The velocity fields induced by regular breaking waves past a fixed bar on a 1:10 rigid plane slop... more The velocity fields induced by regular breaking waves past a fixed bar on a 1:10 rigid plane slope were measured and analysed using a volumetric particle-tracking velocimetry system. Under specific conditions, the wave-mophological features interaction steepens the waves which eventually breaks. The geometry of the boundaries of the present experiments is common in natural environments, where reefs, sand and gravel bars, and submerged coastal structures, interact with the incoming wave field 'affecting' the transport budget of substances (sediment, nutrients and pollutants), with relevant consequences on the water quality. The aims of the present work are the analysis of the flow field in the breaker, the quantification of the terms in the equations usually adopted for modelling the flow and the turbulence. Two sets of attacking monochromatic wave trains with different periods and heights were used to generate a dataset of instantaneous velocity, which was further analysed to extract turbulence. The measurement volume extended from the wave crest to a portion of the domain below the wave trough. The balance of linear momentum for the average field and the balance of turbulence, were scrutinised and included all the terms in a 3D approach. The analysed data and results are original and novel because they include all the contributions derived from the 3D structure of a real flow field, and constitute a huge data set for calibration of numerical codes.

Research paper thumbnail of Pressure Distributions on a Vertical Breakwater: Experimental

Coastal Engineering Proceedings, Feb 1, 2011

This work studies the horizontal and uplift pressure distributions over a caisson founded on poro... more This work studies the horizontal and uplift pressure distributions over a caisson founded on porous materials, and their dependence on the stone diameter and the height of the foundation. For this, tests at a wave flume with an idealized composite breakwater of rectangular section, varying the depth of the foundation of the caisson and the diameter of the stones, were carried on. Eight resistive gauges and eight pressures sensors were used to measure free surface elevations and horizontal and uplift pressure variation, respectively. Results show that: 1) there exist a "saturation" of the reflection coefficient for B/L>0.4, being B the width of the dike and L the wave length, 2) by using the total wave height measured at the toe of the dike in the analysis, the dispersion of the results is significantly reduced; 3) dimensionless run-up and pressures obtained using total wave height mainly depends on the reflection regime and on the relative height of the foundation; 4) maximum uplift and horizontal forces are not always in phase, and three regimes are identified depending on which force dominates; and 5) the relation between the dimensionless forces with the total wave height at the toe of the dike depends mainly on the reflection regime and on the relative foundation height.

Research paper thumbnail of Note on a real gas model for OWC performance

Renewable Energy, 2016

Oscillating water column (OWC) are devices for wave energy extraction equipped with turbines for ... more Oscillating water column (OWC) are devices for wave energy extraction equipped with turbines for energy conversion. The purpose of the present work is to study the thermodynamic of a real gas flow through the turbine and its differences with respect to the ideal gas hypothesis, with the final goal to be applied to OWC systems. The effect of moisture in the air chamber of the OWC entails variations on the atmospheric conditions near the turbine, modifying its performance and efficiency. In this work we study the influence of humid air in the performance of the turbine. Experimental work is carried out and a real gas model is asserted, in order to take a first approach to quantify the extent of influence of the airewater vapour mixture in the turbine performance. The application of a real gas model and the experimental study confirmed the deviations of the turbine performance from the expected values depending on flow rate, moisture and temperature.

Research paper thumbnail of Wave Reflection and Stability Evolution of S-Profile Breakwaters

Coastal Structures 2007 - Proceedings of the 5th Coastal Structures International Conference, CST07, 2009

Research paper thumbnail of Failure of Seabeds with a High Mud Content: An Experimental Study

Coastal Engineering Proceedings, 2014

Seabed instability has been cited as the cause of failure for a number of coastal structures in r... more Seabed instability has been cited as the cause of failure for a number of coastal structures in recent years, stimulating an interest in understanding the interaction between waves, marine structures and the seabed upon which they are built. A series of experimental tests were carried out in a wave flume at the Engineering Institute of the National University of Mexico, to investigate the failure of seabeds with a high mud content and the interaction of the seabed with a scaled structure (vertical breakwater) and regular waves (T = 0.6, 0.8 and 1.0 s; H = 6, 8 and 10 cm), through the analysis of pore pressure distribution. Three different materials were tested: 100, 90 and 85 % mud content, mixed with natural sand and water. Pore pressure build-up was registered in the tests with 85 % of mud content, and knowing that a buildup precedes soil liquefaction, failure may have occurred. But in these cases the maximum pressure in the tests did not exceed the critical value and no liquefaction was observed. For soils of 90 and 100 % mud content, the pore pressure shows a homogeneous vertical behaviour and only pore pressure falls were registered. This phenomenon may be attributed to the cohesion effect in the mud particles and to the consolidation process.

Research paper thumbnail of Experimental Verification of Mound Breakwater Built with an S-Profile

Coastal Engineering 2006 - Proceedings of the 30th International Conference, 2007

In this paper, laboratory data of breakwater damage, profile evolution and energy fluxes over an ... more In this paper, laboratory data of breakwater damage, profile evolution and energy fluxes over an homogeneous mound breakwater are presented and discussed. The experiments were done over two models, consisting on a mound breakwater composed of cubes of the same size, ...

Research paper thumbnail of Pressure Distributions on a Vertical Breakwater: Experimental

Coastal Engineering Proceedings, 2011

This work studies the horizontal and uplift pressure distributions over a caisson founded on poro... more This work studies the horizontal and uplift pressure distributions over a caisson founded on porous materials, and their dependence on the stone diameter and the height of the foundation. For this, tests at a wave flume with an idealized composite breakwater of rectangular section, varying the depth of the foundation of the caisson and the diameter of the stones, were carried on. Eight resistive gauges and eight pressures sensors were used to measure free surface elevations and horizontal and uplift pressure variation, respectively. Results show that: 1) there exist a "saturation" of the reflection coefficient for B/L>0.4, being B the width of the dike and L the wave length, 2) by using the total wave height measured at the toe of the dike in the analysis, the dispersion of the results is significantly reduced; 3) dimensionless run-up and pressures obtained using total wave height mainly depends on the reflection regime and on the relative height of the foundation; 4) maximum uplift and horizontal forces are not always in phase, and three regimes are identified depending on which force dominates; and 5) the relation between the dimensionless forces with the total wave height at the toe of the dike depends mainly on the reflection regime and on the relative foundation height.

Research paper thumbnail of Determinação de forças actuantes em quebra-mares verticais e mistos

Revista da Gestão Costeira Integrada, 2012

Research paper thumbnail of An Unified Design Method of Maritime Works Against Waves

Coastal Engineering Proceedings, 2012

This work studies the interaction of a composite breakwater and irregular waves as a function of ... more This work studies the interaction of a composite breakwater and irregular waves as a function of the breakwater geometry and wave characteristics. For this, tests in a flume wave were carried out. The model consisted of a composite breakwater with rectangular cross section and with the width, foundation depth and stone diameter varying in order to know their influence in the breakwater behavior. Results show that reflection coefficient increase with B/L (where B is the width of the dike and L is the wave length) until a maximum value (saturation point) from which it is constant or decreases slightly. Before this point, reflection coefficient depends on breakwater geometry and wave characteristics and when the dike reaches the saturation regime, it only depends on stone diameter or porosity. The value of the sea water elevation at the wall and the horizontal pressure depends on the reflection coefficient. Finally, the relationship between horizontal and vertical forces is linear depending on the reflection regime. This analysis shows that energy distribution is the main variable to know the structural behavior of a dike. Based on these results, a methodology to obtain the loads over the composite breakwater is proposed.

Research paper thumbnail of Forces and Subpressures on Non-Overtoppable Vertical Breakwaters

Coastal Structures 2011, 2012

ABSTRACT This paper presents an analysis of measured data of pressures and subpressures, as well ... more ABSTRACT This paper presents an analysis of measured data of pressures and subpressures, as well as horizontal and vertical forces exerted by waves on a non-overtopping vertical breakwater during storm events. The breakwater studied was the North Breakwater of the Port of Gijón (Spain). The forces were obtained by integrating the measured pressures from 17 sensors spread across the central body, the superstructure and the bottom of the caisson. The results show the influence of the distribution of energy flows on the pressure laws due to the wave-breakwater interaction. The maximum sea-level reference pressure is directly proportional to the free surface at that instant. The simultaneity of the maximum horizontal and vertical forces in a given sea state was also analyzed, concluding that these forces are not always in phase.

Research paper thumbnail of Experimental analysis of the coherent structures and turbulence past a hydrofoil in stalling condition beneath a water–air interface

European Journal of Mechanics - B/Fluids, 2014

Research paper thumbnail of Study of the turbulence in the air-side and water-side boundary layers in experimental laboratory wind induced surface waves

This study detailed the structure of turbulence in the air-side and water-side boundary lay... more This study detailed the structure of turbulence in the air-side and water-side boundary layers in wind­ induced surface waves. lnside the air boundary layer, the kurtosis is always greater than 3 (the value for nor­mal distribution) for both horizontal and vertical velocity fluctuations.The skewness for the horizontal veloc­ity is negative, but the skewness for the vertical velocity is always positive. On the water side, the kurtosis is always greater than 3, and the skewness is slightly negative for the horizontal velocity and slightly positive for the vertical velocity.The statistics of the angle between the instantaneous vertical fluctuation and the in­stantaneous horizontal velocity in the air is similar to those obtained over solid walls.Measurements in water show a large variance, and the peak is biased towards negative angles.In the quadrant analysis, the contribu­tion of quadrants Q2 and Q4 is dominant on both the air side and the water side.The non-dimensional relative contributions and the concentration match fairly well near the interface. Sweeps in the air side (belonging to quadrant Q4) act directly on the interface and exert pressure fluctuations, which, in addition to the tangential stress and form drag, lead to the growth of the waves. The water drops detached from the crest and accelerated by the wind can play a major role in transferring momentum and in enhancing the turbulence level in the water side.
On the air side, the Reynolds stress tensor's principal axes are not collinear with the strain rate tensor, and show an angle aa =-20° to-25°. On the water side, the angle is aa = -40° to-45°. The ratio be­tween the maximum and the minimum principal stresses is aolab =3 to 4 on the air side, and arJ ab=1.5 to 3 on the water side. In this respect, the air-side flow behaves like a classical boundary layer on a solid wall, while the water-side flow resembles a wake. The frequency of bursting on the water side in­ creases significantly along the flow, which can be attributed to micro-breaking effects - expected to be more frequent at larger fetches.

Research paper thumbnail of 3D flow measurements in regular breaking waves past a fixed submerged bar on an impermeable plane slope

The velocity fields induced by regular breaking waves past a fixed bar on a 1:10 rigid plane slop... more The velocity fields induced by regular breaking waves past a fixed bar on a 1:10 rigid plane slope were measured and analysed using a volumetric particle-tracking velocimetry system. Under specific conditions, the wave-mophological features interaction steepens the waves which eventually breaks. The geometry of the boundaries of the present experiments is common in natural environments, where reefs, sand and gravel bars, and submerged coastal structures, interact with the incoming wave field 'affecting' the transport budget of substances (sediment, nutrients and pollutants), with relevant consequences on the water quality. The aims of the present work are the analysis of the flow field in the breaker, the quantification of the terms in the equations usually adopted for modelling the flow and the turbulence. Two sets of attacking monochromatic wave trains with different periods and heights were used to generate a dataset of instantaneous velocity, which was further analysed to extract turbulence. The measurement volume extended from the wave crest to a portion of the domain below the wave trough. The balance of linear momentum for the average field and the balance of turbulence, were scrutinised and included all the terms in a 3D approach. The analysed data and results are original and novel because they include all the contributions derived from the 3D structure of a real flow field, and constitute a huge data set for calibration of numerical codes.