The Experts below are selected from a list of 14280 Experts worldwide ranked by ideXlab platform
Stuart A. Weinstein - One of the best experts on this subject based on the ideXlab platform.
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The effect of convection planform on the toroidal–poloidal energy ratio
Earth and Planetary Science Letters, 1998Co-Authors: Stuart A. WeinsteinAbstract:Abstract This study investigates the influence of thermal convection planform geometry on the pattern of surface deformation in a dynamic model of plate–mantle coupling. The lithosphere is viewed as a distinct rheological layer and is modeled as a thin, non-Newtonian sheet that is dynamically coupled to a three-dimensional, convecting Newtonian layer. The results of numerical experiments show that Planforms which possess a high degree of symmetry excite only small amounts of toroidal energy in the thin non-Newtonian sheet and thus have low toroidal–poloidal energy ratios. Asymmetric Planforms tend to possess toroidal–poloidal energy ratios that are one to two orders of magnitude larger than symmetric cases. The results of this study suggest the precipitous drop in the toroidal–poloidal energy ratio for the Earth's surface velocity field that occurred in the late Cretaceous–early Cenozoic resulted from the late Cretaceous superplume which organized mantle flow into a higher degree of symmetry.
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convection Planforms in a fluid with a temperature dependent viscosity beneath a stress free upper boundary
Geophysical Research Letters, 1991Co-Authors: Stuart A. Weinstein, Ulrich R. ChristensenAbstract:This study presents the results of a joint numerical and laboratory study of 3-D Planforms of time-dependent convection in a Newtonian fluid layer with a temperature-dependent viscosity. Planforms are found for the case in which the fluid is bounded from above by a stress-free boundary and below by a rigid boundary and compared to the Planforms found when the fluid layer is bounded by rigid boundaries. All of the laboratory and numerical experiments were performed with nearly the same values of the Rayleigh number Ra1/2 (1 × 105) and viscosity ratio µr (50), and viscosity law to allow direct comparisons. When the fluid layer is bounded by rigid boundaries the observed Planforms are the spoke patterns, which are an interconnected network of descending and ascending sheets. However, when the upper boundary is stress-free, the morphology of the downwellings change from spokes to a dendritic network of descending sheets and the wavelength of the planform is more than 3 times as large as the spoke pattern planform. In both cases the numerical and laboratory experiments are in good agreement.
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Convection Planforms in a fluid with a temperature‐dependent viscosity beneath a stress‐free upper boundary
Geophysical Research Letters, 1991Co-Authors: Stuart A. Weinstein, Ulrich R. ChristensenAbstract:This study presents the results of a joint numerical and laboratory study of 3-D Planforms of time-dependent convection in a Newtonian fluid layer with a temperature-dependent viscosity. Planforms are found for the case in which the fluid is bounded from above by a stress-free boundary and below by a rigid boundary and compared to the Planforms found when the fluid layer is bounded by rigid boundaries. All of the laboratory and numerical experiments were performed with nearly the same values of the Rayleigh number Ra1/2 (1 × 105) and viscosity ratio µr (50), and viscosity law to allow direct comparisons. When the fluid layer is bounded by rigid boundaries the observed Planforms are the spoke patterns, which are an interconnected network of descending and ascending sheets. However, when the upper boundary is stress-free, the morphology of the downwellings change from spokes to a dendritic network of descending sheets and the wavelength of the planform is more than 3 times as large as the spoke pattern planform. In both cases the numerical and laboratory experiments are in good agreement.
Ulrich R. Christensen - One of the best experts on this subject based on the ideXlab platform.
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convection Planforms in a fluid with a temperature dependent viscosity beneath a stress free upper boundary
Geophysical Research Letters, 1991Co-Authors: Stuart A. Weinstein, Ulrich R. ChristensenAbstract:This study presents the results of a joint numerical and laboratory study of 3-D Planforms of time-dependent convection in a Newtonian fluid layer with a temperature-dependent viscosity. Planforms are found for the case in which the fluid is bounded from above by a stress-free boundary and below by a rigid boundary and compared to the Planforms found when the fluid layer is bounded by rigid boundaries. All of the laboratory and numerical experiments were performed with nearly the same values of the Rayleigh number Ra1/2 (1 × 105) and viscosity ratio µr (50), and viscosity law to allow direct comparisons. When the fluid layer is bounded by rigid boundaries the observed Planforms are the spoke patterns, which are an interconnected network of descending and ascending sheets. However, when the upper boundary is stress-free, the morphology of the downwellings change from spokes to a dendritic network of descending sheets and the wavelength of the planform is more than 3 times as large as the spoke pattern planform. In both cases the numerical and laboratory experiments are in good agreement.
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Convection Planforms in a fluid with a temperature‐dependent viscosity beneath a stress‐free upper boundary
Geophysical Research Letters, 1991Co-Authors: Stuart A. Weinstein, Ulrich R. ChristensenAbstract:This study presents the results of a joint numerical and laboratory study of 3-D Planforms of time-dependent convection in a Newtonian fluid layer with a temperature-dependent viscosity. Planforms are found for the case in which the fluid is bounded from above by a stress-free boundary and below by a rigid boundary and compared to the Planforms found when the fluid layer is bounded by rigid boundaries. All of the laboratory and numerical experiments were performed with nearly the same values of the Rayleigh number Ra1/2 (1 × 105) and viscosity ratio µr (50), and viscosity law to allow direct comparisons. When the fluid layer is bounded by rigid boundaries the observed Planforms are the spoke patterns, which are an interconnected network of descending and ascending sheets. However, when the upper boundary is stress-free, the morphology of the downwellings change from spokes to a dendritic network of descending sheets and the wavelength of the planform is more than 3 times as large as the spoke pattern planform. In both cases the numerical and laboratory experiments are in good agreement.
Maurizio D'anna - One of the best experts on this subject based on the ideXlab platform.
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:9 Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which 10 deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art 11 shoreline change model coupled with a spectral wave model to address embayed beach shoreline 12 dynamics driven by longshore sediment transport processes. The model is applied to different 13 idealized embayed beach configurations including variations in headland lengths. The model simulates 14 a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of 15 shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed 16 beach curvature and maximum erosion at the upwave side of the embayment increases with increasing 17 headland length. Beach curvature also increases with increasing headland length for headlands long 18 enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach 19 becomes increasingly curved and symmetric, with maximum localised erosion within the embayment 20 decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in 21 amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-22 invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the 23 envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all 24 increasing with decreasing modal directional spreading. Embayed beach rotation characteristic 25 timescale increases with increasing embayed beach length, while the narrower the embayment the 26 smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the 27 influence of embayment characteristics and incident wave conditions on equilibrium planform and 28 shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland 29 sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed 30 beach dynamic planform configuration. 31 Highlights 32 • Embayed beach shoreline response is simulated with a hybrid shoreline model 33 • Headland length and headland sediment bypassing control shoreline response 34 • Wave directional spreading is critical to both mean shoreline and rotation signal 35 • Embayment beach length controls rotation characteristic timescale 36 37 Keywords: embayed beach ; hybrid shoreline model ; headland length ; rotation ; equilibrium 38 beach planform; headland sand bypassing 39 40
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:Abstract Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art shoreline change model coupled with a spectral wave model to address embayed beach shoreline dynamics driven by longshore sediment transport processes. The model is applied to different idealized embayed beach configurations including variations in headland lengths. The model simulates a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed beach curvature and maximum erosion at the upwave side of the embayment increases with increasing headland length. Beach curvature also increases with increasing headland length for headlands long enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach becomes increasingly curved and symmetric, with maximum localised erosion within the embayment decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all increasing with decreasing modal directional spreading. Embayed beach rotation characteristic timescale increases with increasing embayed beach length, while the narrower the embayment the smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the influence of embayment characteristics and incident wave conditions on equilibrium planform and shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed beach dynamic planform configuration.
Bruno Castelle - One of the best experts on this subject based on the ideXlab platform.
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:9 Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which 10 deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art 11 shoreline change model coupled with a spectral wave model to address embayed beach shoreline 12 dynamics driven by longshore sediment transport processes. The model is applied to different 13 idealized embayed beach configurations including variations in headland lengths. The model simulates 14 a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of 15 shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed 16 beach curvature and maximum erosion at the upwave side of the embayment increases with increasing 17 headland length. Beach curvature also increases with increasing headland length for headlands long 18 enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach 19 becomes increasingly curved and symmetric, with maximum localised erosion within the embayment 20 decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in 21 amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-22 invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the 23 envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all 24 increasing with decreasing modal directional spreading. Embayed beach rotation characteristic 25 timescale increases with increasing embayed beach length, while the narrower the embayment the 26 smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the 27 influence of embayment characteristics and incident wave conditions on equilibrium planform and 28 shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland 29 sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed 30 beach dynamic planform configuration. 31 Highlights 32 • Embayed beach shoreline response is simulated with a hybrid shoreline model 33 • Headland length and headland sediment bypassing control shoreline response 34 • Wave directional spreading is critical to both mean shoreline and rotation signal 35 • Embayment beach length controls rotation characteristic timescale 36 37 Keywords: embayed beach ; hybrid shoreline model ; headland length ; rotation ; equilibrium 38 beach planform; headland sand bypassing 39 40
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:Abstract Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art shoreline change model coupled with a spectral wave model to address embayed beach shoreline dynamics driven by longshore sediment transport processes. The model is applied to different idealized embayed beach configurations including variations in headland lengths. The model simulates a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed beach curvature and maximum erosion at the upwave side of the embayment increases with increasing headland length. Beach curvature also increases with increasing headland length for headlands long enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach becomes increasingly curved and symmetric, with maximum localised erosion within the embayment decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all increasing with decreasing modal directional spreading. Embayed beach rotation characteristic timescale increases with increasing embayed beach length, while the narrower the embayment the smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the influence of embayment characteristics and incident wave conditions on equilibrium planform and shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed beach dynamic planform configuration.
Déborah Idier - One of the best experts on this subject based on the ideXlab platform.
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:9 Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which 10 deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art 11 shoreline change model coupled with a spectral wave model to address embayed beach shoreline 12 dynamics driven by longshore sediment transport processes. The model is applied to different 13 idealized embayed beach configurations including variations in headland lengths. The model simulates 14 a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of 15 shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed 16 beach curvature and maximum erosion at the upwave side of the embayment increases with increasing 17 headland length. Beach curvature also increases with increasing headland length for headlands long 18 enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach 19 becomes increasingly curved and symmetric, with maximum localised erosion within the embayment 20 decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in 21 amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-22 invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the 23 envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all 24 increasing with decreasing modal directional spreading. Embayed beach rotation characteristic 25 timescale increases with increasing embayed beach length, while the narrower the embayment the 26 smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the 27 influence of embayment characteristics and incident wave conditions on equilibrium planform and 28 shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland 29 sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed 30 beach dynamic planform configuration. 31 Highlights 32 • Embayed beach shoreline response is simulated with a hybrid shoreline model 33 • Headland length and headland sediment bypassing control shoreline response 34 • Wave directional spreading is critical to both mean shoreline and rotation signal 35 • Embayment beach length controls rotation characteristic timescale 36 37 Keywords: embayed beach ; hybrid shoreline model ; headland length ; rotation ; equilibrium 38 beach planform; headland sand bypassing 39 40
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Modelling of embayed beach equilibrium planform and rotation signal
Geomorphology, 2020Co-Authors: Bruno Castelle, Arthur Robinet, Déborah Idier, Maurizio D'annaAbstract:Abstract Embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries, which deeply affect equilibrium beach planform and shoreline dynamics. We use LX-Shore, a state-of-the-art shoreline change model coupled with a spectral wave model to address embayed beach shoreline dynamics driven by longshore sediment transport processes. The model is applied to different idealized embayed beach configurations including variations in headland lengths. The model simulates a large range of equilibrium embayed beach Planforms and associated spatial and temporal modes of shoreline variability. For short headlands enabling occasional headland sand bypassing, both embayed beach curvature and maximum erosion at the upwave side of the embayment increases with increasing headland length. Beach curvature also increases with increasing headland length for headlands long enough to prevent any headland sand bypassing. In contrast, at the same time, embayed beach becomes increasingly curved and symmetric, with maximum localised erosion within the embayment decreasing in intensity. When there is no headland sand bypassing, rotation signal decreases in amplitude and becomes increasingly symmetric with increasing headland length. The modal (time-invariant) directional spreading of incident waves is critical to embayed beach behaviour, with the envelope and variance of cross-shore shoreline change and time-averaged shoreline curvature all increasing with decreasing modal directional spreading. Embayed beach rotation characteristic timescale increases with increasing embayed beach length, while the narrower the embayment the smaller the cross-shore amplitude of shoreline variability. Our simulations provide new insight into the influence of embayment characteristics and incident wave conditions on equilibrium planform and shoreline dynamics of embayed beaches. This work also implies that the degree of potential headland sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed beach dynamic planform configuration.
