Cheryl Blain - Academia.edu (original) (raw)
Papers by Cheryl Blain
The flow in the vicinity of an idealized tidal inlet is studied using the nonlinear finite-elemen... more The flow in the vicinity of an idealized tidal inlet is studied using the nonlinear finite-element model ADCIRC. The principal aim is to establish a database of results to identify, analyze, and explain the processes in and near tidal inlets of the Mississippi Sound region in the northeast Gulf of Mexico. Coastal waters in the northeast Gulf of Mexico are forced by a combination of tides, river runoff, and wind. The effects of these forcings, and that of advection, Coriolis acceleration, and barrier islands are studied. The two-dimensional (2D) depth-averaged results derived from the three-dimensional (3D) model computations are similar to those computed by the 2D model for the tidally driven flow, whereas they are significantly different for the wind- and river-induced flow. Counter-rotating eddies are produced by tides when convective terms are included in the simulation. Coriolis acceleration accounts for the asymmetry within and outside the inlet. The flow in the region is weakl...
The continued necessity of military special forces operations in riverine and coastal environment... more The continued necessity of military special forces operations in riverine and coastal environments along with increasing civilian concerns related to sediment transport, search and rescue, pollutant dispersal, and coastal restoration, have resulted in the need for detailed knowledge of currents and water levels in coastal, estuarine, and riverine environments. This demand for information at highly resolved spatial and temporal scales and the availability of massively parallel computer resources has brought to the forefront the capabilities of finite element (FE)-based coastal ocean circulation models. The use by these models of unstructured triangular meshes permits a large degree of flexibility in representing the complexities of coastal environments associated with convoluted shorelines, and steep gradients in currents or bathymetry. Ultimately this flexibility results in model predictions over periods of hours or less at spatial scales that range from meters to kilometers. Unstru...
This report describes the implementation of the QUODDY finite-element circulation model on shared... more This report describes the implementation of the QUODDY finite-element circulation model on shared-memory multiprocessor computers using OpenMP. Because all code modifications were restricted to the main computational routines and no changes are required in the user interface and configuration files, the parallel code can be seamlessly integrated into existing regional applications of the model. Bit-for-bit matching between serial and parallel execution has been achieved. The code modifications reduced the execution time per model time step of one test case from 21.1 s on a single processor to about 1.4 s on 32 processors. By reducing turnaround time and enabling substantial increases in model resolution, the parallel code will benefit further coastal ocean model development.
Acta Oceanologica Sinica -English Edition-
Estuarine and Coastal Modeling (2001), 2002
The goal is to fulfill the US Navy's need for a relocatable, robust operational coastal forec... more The goal is to fulfill the US Navy's need for a relocatable, robust operational coastal forecast system by developing and transitioning a high-resolution, coastal circulation model into the Naval Oceanographie Office's operational environment. The coastal circulation model undergoing transition is a three-dimensional, finite-element based hydrodynamic model, the Advanced Circulation Model for Shelves, Coastal Seas, and Estuaries (ADCIRC). Its unstructured grid
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503,
Prescribed by ANSI Std. Z39.18
Continental Shelf Research, 2005
A two-dimensional barotropic finite element model with the grid resolution varying between 0.2 an... more A two-dimensional barotropic finite element model with the grid resolution varying between 0.2 and 2km and forced by eight principle constituents (Q1, O1, P1, K1, N2, M2, S2, and K2) was used to compute tidal elevations and currents in the Bab el Mandab Strait. Good agreement is achieved with the available observations for both diurnal and semidiurnal tidal currents and
Prescribed by ANSI Std. Z39.18
2003 User Group Conference. Proceedings, 2003
Estuarine and Coastal Modeling (2001), 2002
This study focuses on modeling the 2D, depth-averaged circulation of an ideal inlet that is drive... more This study focuses on modeling the 2D, depth-averaged circulation of an ideal inlet that is driven by waves and tides using a coupled hydrodynamic-wave model. The circulation of an ideal inlet, consisting of a shallow bay of constant depth connected by a relatively narrow inlet to a sloping coastal shelf region, is studied. Circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The ideal inlet is also simulated with only wave forcing to better understand the effect of wave-current interaction on the circulation. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers.
Developments in Water Science, 2004
Estuarine and Coastal Modeling (2001), 2002
In shelf regions with steep bathymetry in the presence of density gradients, the computation of t... more In shelf regions with steep bathymetry in the presence of density gradients, the computation of the baroclinic pressure gradient term in 3D shallow water models may either become unstable or physically unrealistic. This manuscript examines four algorithms to compute the baroclinic pressure gradient term in finite element models. Two common systems for discretizing the vertical are sigma or zlevel coordinates. In turn, permutations of these two coordinate systems serve as the basis for the four different algorithms examined herein. All are implemented in the context of the finite element hydrodynamic model, ADCIRC. Several density gradients that vary horizontally and vertically, with the pycnocline occurring at different depths, are used to evaluate the methods in a three-dimensional box grid with variable bathymetry. Initial testing, the subject of this work, focuses on model behavior for simplified problem with known analytic solutions. Long term goals for this study (the subject of subsequent papers) are three-fold: 1) to determine the vertical node placement algorithm that produces the most stable and physically realistic results; 2) to determine the interplay of vertical and horizontal resolution (and bathymetry and density profile), while considering simulation time; and 3) to produce accurate 3D flow fields and baroclinic pressure gradients. Outcomes from the study will be used to direct on-going modeling research in the Mississippi Sound.
A better understanding of nearshore circulation is crucial to problems concerning coastal zone ma... more A better understanding of nearshore circulation is crucial to problems concerning coastal zone management such as sediment transport, pollutant transport, water quality, and ship navigation. The two main questions we wish to address in this study are: 1) Is it possible to apply a shelf-scale hydrodynamic model to nearshore environments and 2) How sensitive is the model to changes in its physical parameters (e.g. nonlinear bottom friction coefficient, lateral dispersion coefficient)? ADCIRC-2DDI, a two-dimensional finite element barotropic hydrodynamic model, is used to study the contributions of nearshore nonlinear processes (wave-current interactions, nonlinear bottom stress, advection, lateral diffusion/dispersion) within the context of wave-induced nearshore flow for planar and barred-planar beaches. The mesh resolution necessary for capturing nearshore circulation within the numerical model was determined through a convergence study. The sensitivity of the model to its nonlinear...
The model forecast system comprising the finite element-based hydrodynamic model ADCIRC-2DDI, the... more The model forecast system comprising the finite element-based hydrodynamic model ADCIRC-2DDI, the Navy Operational Global Atmospheric Prediction System (NOGAPS), and the Grenoble tidal database (FES95.2.1) is evaluated in the Western North Atlantic Ocean under an operational test (OPTEST) defined by the Naval Oceanographic Office (NAVOCEANO). Using tidal forcing at the open boundary, model forecasts of water elevations are made with and without wind forcing and compared to observations available through the National Atmospheric and Oceanic Administration (NOAA). The model forecast system, configuration. and implementation are described at length with respect to the definition of the operational test. data processing, and evaluation criteria. Model predictions fall within the acceptable Navy standard of 20% RMS amplitude error and 60 minutes phase error for both the tides-only and wind- and tidally-driven forecasts.
The Validation Test Report for the Advanced CIRCulation Model, ADCIRC, v45.11 addresses the predi... more The Validation Test Report for the Advanced CIRCulation Model, ADCIRC, v45.11 addresses the prediction of barotropic 2D and 3D currents, water levels and inundation. Validation efforts address 1) the wetting and drying capability, 2) the prediction of surge, inundation and surge-induced currents, 3) the prediction of two- and three-dimensional currents and water levels in a bay, and 4) the prediction of three-dimensional tidal currents in the wake of an island. Lastly, a simulated real-time exercise with the model is conducted during the international sea trial, MREA07, and is used to evaluate the developed enabling software as well as the prediction of 2D barotropic currents. Generally, model predictions of evaluated products are reasonably accurate and realistic for truly barotropic applications. More work is needed to better assess the impact of boundary condition specification on predictive capability and to determine the model sensitivity to the 3D turbulence closure formulatio...
The flow in the vicinity of an idealized tidal inlet is studied using the nonlinear finite-elemen... more The flow in the vicinity of an idealized tidal inlet is studied using the nonlinear finite-element model ADCIRC. The principal aim is to establish a database of results to identify, analyze, and explain the processes in and near tidal inlets of the Mississippi Sound region in the northeast Gulf of Mexico. Coastal waters in the northeast Gulf of Mexico are forced by a combination of tides, river runoff, and wind. The effects of these forcings, and that of advection, Coriolis acceleration, and barrier islands are studied. The two-dimensional (2D) depth-averaged results derived from the three-dimensional (3D) model computations are similar to those computed by the 2D model for the tidally driven flow, whereas they are significantly different for the wind- and river-induced flow. Counter-rotating eddies are produced by tides when convective terms are included in the simulation. Coriolis acceleration accounts for the asymmetry within and outside the inlet. The flow in the region is weakl...
The continued necessity of military special forces operations in riverine and coastal environment... more The continued necessity of military special forces operations in riverine and coastal environments along with increasing civilian concerns related to sediment transport, search and rescue, pollutant dispersal, and coastal restoration, have resulted in the need for detailed knowledge of currents and water levels in coastal, estuarine, and riverine environments. This demand for information at highly resolved spatial and temporal scales and the availability of massively parallel computer resources has brought to the forefront the capabilities of finite element (FE)-based coastal ocean circulation models. The use by these models of unstructured triangular meshes permits a large degree of flexibility in representing the complexities of coastal environments associated with convoluted shorelines, and steep gradients in currents or bathymetry. Ultimately this flexibility results in model predictions over periods of hours or less at spatial scales that range from meters to kilometers. Unstru...
This report describes the implementation of the QUODDY finite-element circulation model on shared... more This report describes the implementation of the QUODDY finite-element circulation model on shared-memory multiprocessor computers using OpenMP. Because all code modifications were restricted to the main computational routines and no changes are required in the user interface and configuration files, the parallel code can be seamlessly integrated into existing regional applications of the model. Bit-for-bit matching between serial and parallel execution has been achieved. The code modifications reduced the execution time per model time step of one test case from 21.1 s on a single processor to about 1.4 s on 32 processors. By reducing turnaround time and enabling substantial increases in model resolution, the parallel code will benefit further coastal ocean model development.
Acta Oceanologica Sinica -English Edition-
Estuarine and Coastal Modeling (2001), 2002
The goal is to fulfill the US Navy's need for a relocatable, robust operational coastal forec... more The goal is to fulfill the US Navy's need for a relocatable, robust operational coastal forecast system by developing and transitioning a high-resolution, coastal circulation model into the Naval Oceanographie Office's operational environment. The coastal circulation model undergoing transition is a three-dimensional, finite-element based hydrodynamic model, the Advanced Circulation Model for Shelves, Coastal Seas, and Estuaries (ADCIRC). Its unstructured grid
Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503,
Prescribed by ANSI Std. Z39.18
Continental Shelf Research, 2005
A two-dimensional barotropic finite element model with the grid resolution varying between 0.2 an... more A two-dimensional barotropic finite element model with the grid resolution varying between 0.2 and 2km and forced by eight principle constituents (Q1, O1, P1, K1, N2, M2, S2, and K2) was used to compute tidal elevations and currents in the Bab el Mandab Strait. Good agreement is achieved with the available observations for both diurnal and semidiurnal tidal currents and
Prescribed by ANSI Std. Z39.18
2003 User Group Conference. Proceedings, 2003
Estuarine and Coastal Modeling (2001), 2002
This study focuses on modeling the 2D, depth-averaged circulation of an ideal inlet that is drive... more This study focuses on modeling the 2D, depth-averaged circulation of an ideal inlet that is driven by waves and tides using a coupled hydrodynamic-wave model. The circulation of an ideal inlet, consisting of a shallow bay of constant depth connected by a relatively narrow inlet to a sloping coastal shelf region, is studied. Circulation within the inlet is examined during the flood, slack, and ebb phases of the tidal cycle. The ideal inlet is also simulated with only wave forcing to better understand the effect of wave-current interaction on the circulation. The influence of the various forcings on bay/inlet circulation is further investigated by the introduction of Lagrangian tracers.
Developments in Water Science, 2004
Estuarine and Coastal Modeling (2001), 2002
In shelf regions with steep bathymetry in the presence of density gradients, the computation of t... more In shelf regions with steep bathymetry in the presence of density gradients, the computation of the baroclinic pressure gradient term in 3D shallow water models may either become unstable or physically unrealistic. This manuscript examines four algorithms to compute the baroclinic pressure gradient term in finite element models. Two common systems for discretizing the vertical are sigma or zlevel coordinates. In turn, permutations of these two coordinate systems serve as the basis for the four different algorithms examined herein. All are implemented in the context of the finite element hydrodynamic model, ADCIRC. Several density gradients that vary horizontally and vertically, with the pycnocline occurring at different depths, are used to evaluate the methods in a three-dimensional box grid with variable bathymetry. Initial testing, the subject of this work, focuses on model behavior for simplified problem with known analytic solutions. Long term goals for this study (the subject of subsequent papers) are three-fold: 1) to determine the vertical node placement algorithm that produces the most stable and physically realistic results; 2) to determine the interplay of vertical and horizontal resolution (and bathymetry and density profile), while considering simulation time; and 3) to produce accurate 3D flow fields and baroclinic pressure gradients. Outcomes from the study will be used to direct on-going modeling research in the Mississippi Sound.
A better understanding of nearshore circulation is crucial to problems concerning coastal zone ma... more A better understanding of nearshore circulation is crucial to problems concerning coastal zone management such as sediment transport, pollutant transport, water quality, and ship navigation. The two main questions we wish to address in this study are: 1) Is it possible to apply a shelf-scale hydrodynamic model to nearshore environments and 2) How sensitive is the model to changes in its physical parameters (e.g. nonlinear bottom friction coefficient, lateral dispersion coefficient)? ADCIRC-2DDI, a two-dimensional finite element barotropic hydrodynamic model, is used to study the contributions of nearshore nonlinear processes (wave-current interactions, nonlinear bottom stress, advection, lateral diffusion/dispersion) within the context of wave-induced nearshore flow for planar and barred-planar beaches. The mesh resolution necessary for capturing nearshore circulation within the numerical model was determined through a convergence study. The sensitivity of the model to its nonlinear...
The model forecast system comprising the finite element-based hydrodynamic model ADCIRC-2DDI, the... more The model forecast system comprising the finite element-based hydrodynamic model ADCIRC-2DDI, the Navy Operational Global Atmospheric Prediction System (NOGAPS), and the Grenoble tidal database (FES95.2.1) is evaluated in the Western North Atlantic Ocean under an operational test (OPTEST) defined by the Naval Oceanographic Office (NAVOCEANO). Using tidal forcing at the open boundary, model forecasts of water elevations are made with and without wind forcing and compared to observations available through the National Atmospheric and Oceanic Administration (NOAA). The model forecast system, configuration. and implementation are described at length with respect to the definition of the operational test. data processing, and evaluation criteria. Model predictions fall within the acceptable Navy standard of 20% RMS amplitude error and 60 minutes phase error for both the tides-only and wind- and tidally-driven forecasts.
The Validation Test Report for the Advanced CIRCulation Model, ADCIRC, v45.11 addresses the predi... more The Validation Test Report for the Advanced CIRCulation Model, ADCIRC, v45.11 addresses the prediction of barotropic 2D and 3D currents, water levels and inundation. Validation efforts address 1) the wetting and drying capability, 2) the prediction of surge, inundation and surge-induced currents, 3) the prediction of two- and three-dimensional currents and water levels in a bay, and 4) the prediction of three-dimensional tidal currents in the wake of an island. Lastly, a simulated real-time exercise with the model is conducted during the international sea trial, MREA07, and is used to evaluate the developed enabling software as well as the prediction of 2D barotropic currents. Generally, model predictions of evaluated products are reasonably accurate and realistic for truly barotropic applications. More work is needed to better assess the impact of boundary condition specification on predictive capability and to determine the model sensitivity to the 3D turbulence closure formulatio...