Investigation of Tidally Induced Turbulent Flow

Source: https://erdc-library.erdc.dren.mil/jspui/A two-dimensional numerical model was developed for the case of tidally induced turbulent flow. An analysis of shallow-water waves is made followed by the development of a second-order closure Reynolds stress turbulence model for the specific application to shallow-water waves. Verification of the resulting numerical model is made to existing steady-state turbulent flume data

Stable Three-Dimensional Biperiodic Waves in Shallow Water

Source: https://erdc-library.erdc.dren.mil/jspui/The Kadomtsev-Petviashvili (KP) equation is tested as a model for these biperiodic waves. This equation is the direct three-dimensional generalization of the famous KortewegdeVries (KdV) equation for weakly nonlinear waves in two dimensions. It is known that the KP equation admits an infinite dimensional family of periodic solutions which are defined in terms of Riemann theta functions of genus N. Genus 2 solutions have two real periods and are similar in structure to the hexagonally shaped waves observed in the experiments. A methodology is developed which relates the free parameters of the genus 2 solution to the temporal and spatial data of the experimentally generated waves. Comparisons of exact genus 2 solutions with measured data show excellent agreement over the entire range of experiments. Even though near-breaking waves and highly three-dimensional wave forms are encountered, the total rms error between experiment and KP theory never exceeds 20 percent, although known sources of error are introduced. Hence, the KP equation appears to be a very robust model of nonlinear three-dimensional waves propagating in shallow water, reminiscent of the KdV equation in two dimensions

Coastal Engineering Studies in Support of Virginia Beach, Virginia, Beach Erosion Control and Hurricane Protection Project: Report 3

Source: https://erdc-library.erdc.dren.mil/jspui/A study was conducted to determine beach-fill berm dimensions in order to provide backshore areas with sufficient protection from storm-induced flooding. The beach-fill design was part of a beach erosion control and hurricane protection project along approximately 6 miles of Virginia Beach, Virginia. A modified Kriebel cross-shore numerical model was used to evaluate various berm dimensions for several hurricane and northeaster storm events. Results of the modeling effort indicated a 100-ft-wide berm with an elevation of 5.4 ft National Geodetic Vertical Datum would provide sufficient protection for the 100-yeastorm event. Grain size analysis of the native beach and seven borrow areas indicated that an overfill ratio of 1.37 was appropriate for the design. Applying this value, initial beachfill volumes were calculated in addition to 2- and 5-year advanced nourishment quantities

Computation of Long-Term Three-Dimensional Hydrodynamics of New York Bight

A time-varying three-dimensional (3D) numerical hydrodynamic model has been applied to the New York Bight to provide flow fields to a 3D water quality model. The spatial computational domain extends from Cape May, New Jersey at its south-west end and Narragansett Bay, Rhode Island, at the north-east end and seaward to the shelf-break. As illustrated below, the numerical model has more than 2500 active horizontal cells and ten vertical layers. Features of the hydrodynamic model include coupling of temperature grids to better represent geometric features, and an algebraic vertical turbulence model based upon the assumption that turbulence production and dissipation are in equilibrium. Using historical forcing data, flow fields for the period of September 1975 - October 1976 have been computed. These results demonstrate that the numerical model is able to accurately reproduce the observed salinity field

A User's Guide to the N-Line Model: A Numerical Model to Simulate Sediment Transport in the Vicinity of Coastal Structures

Source: https://erdc-library.erdc.dren.mil/jspui/A user's manual was developed for the W-line numerical sediment transport model by the Coastal Engineering Research Center (CERC). This report provides the necessary guidance, complete with multiple example applications which include model input and output, for using the N-line numerical model. Capabilities of the model include the simulation of (a) single or multiple shore-perpendicular structures, (b) single or multiple detached offshore breakwaters, and (c) disposal of material or dredging of material in the coastal zone. Model parameters are discussed in order to guide the potential user to a successful application of the model. The N-line model is versatile, easy to use, and capable of producing dependable results when used for appropriate applications. The documentation presented in this manual is intended to cover only the breakwater subroutine, Since conceptual modifications were not made to the original model, the original documentation, presented in CERC's report MR 83-10, should be obtained by any potential user of the model. The N-line model is useful in showing qualitative trends for a complex case such as Lakeview Park, Lorain, Ohio. Some of the drawbacks of the program when modeling Lakeview Park, such as the inability to reach an equilibrium shoreline, and the low sinuosity of the shoreline when influenced by breakwater segments, could possibly be successfully modeled by modifying the different input parameters, such as the ADEAN parameter and/or initial shoreline location and/or the model code. Perhaps then a quantitative verification of the model could be made. However, in this case, the model would have then been tailored to produce a previously known result. A project cannot be successfully modeled without experimenting with different timesteps, space-steps, contour depths, shoreline locations, and structure configurations, A wave climate representative of the area being modeled is also very important. Finally, the response of the model to a particular setup must be interpreted with engineering judgment

Coastal Processes from Asbury Park to Manasquan, New Jersey

Source: https://erdc-library.erdc.dren.mil/jspui/This report describes a study of coastal processes along the Atlantic coast from Asbury Park to Manasquan, New Jersey. Numerical predictive models for storm surge, dune erosion, nearshore wave transformation, and shoreline response were used in conjunction with an intensive analysis of available physical data to assist in the design, evaluation, and implementation of comprehensive shore protection plans for this densely populated and heavily structured coastal region. the study was divided into four independent but interrelated areas: (a) deepwater wave climate analysis and nearshore wave transformation, (b) long-term shoreline response numerical modeling, (c) development of coastal stage-frequency relationships, and (d) numerical modeling of storm-induced dune erosion. The results, interrelations, and recommendations of these tasks are presented in the main body of the report together with guidance for the interpretation of the numerical model results. The statistics of the wave hindcast data base, along with graphical representations of the model results, are given in the appendices. Six proposed and four revised design alternatives were evaluated using the shoreline response model to predict the platforms evolution of the beach. Cross-shore responses of the proposed design alternatives were evaluated in a probabilistic manner using the dune erosion model in conjunction with the stage-frequency relationships