IOWA INST OF HYDRAULIC RESEARCH IOWA CITY
Most widely held works by IOWA INST OF HYDRAULIC RESEARCH IOWA CITY
Experimental Study of the Wavemaking of Horizontally-Oriented Vorticity in a Wake ( Book )
1 edition published in 1974 in English and held by 2 libraries worldwide
Towing-tank experiments were conducted in order to investigate the wavemaking of horizontally-oriented vorticity in a wake. It was found that the amplitudes of the surface disturbance, measured with three capacitance wires, were about one tenth of those generated by a ship model of the same length and Froude number. Furthermore, the wave resistance was about one percent of that obtained for a Series-60 model of the same wetted-surface area. (Author).
Viscous Effect on Ship Wave Resistance ( Book )
1 edition published in 1983 in English and held by 2 libraries worldwide
Topics contained in this report are: (1) The methods of conformal mapping and analytic continuation are applied to obtain slender-body centerplane distributions; and (2) Three closed-form approximations to the double-integral 'near field' term in the Havelock Green function are derived. An application to centerplane source distributions for ship-wave problems is discussed.
Calculation of the Viscous Resistance of Bodies of Revolution ( Book )
1 edition published in 1973 in English and held by 2 libraries worldwide
The flow in the tail region of a body of revolution is a complex one since there the boundary layer often grows to a thickness many times the local radius of the body and there results a strong interaction between the boundary layer and the external potential flow. The influence of making simplifying assumptions concerning the flow in this region in conventional drag-calculation methods is discussed, and assessed by incorporating a method which takes into account the effects of the thick axisymmetric boundary-layer near the tail in an approximate manner. It is shown that this modification leads to a drag-calculation method which gives consistently accurate prediction of the viscous resistance of a wide variety of bodies of revolution. (Author).
GREAT II Upper Mississippi River (Guttenberg, Iowa to Saverton, Missouri) Water Quality Work Group Appendix ( Book )
1 edition published in 1980 in English and held by 2 libraries worldwide
The study programs and recommendations of the three GREAT Teams will be brought together into a river management strategy for the entire Upper Mississippi River. The goal of the study is to present to Congress and the people a river resource management plan that is, above all, realistic - a plan that is technically and economically sound, socially and environmentally acceptable, and capable of being put into action within a reasonable period of time.
Effects of Waves on the Boundary Layer of a Surface-Piercing Body ( Book )
2 editions published between 1985 and 1987 in English and held by 1 library worldwide
The boundary-value problem associated with the boundary-layer development on a surface-piercing body is formulated in a rigorous manner in which proper consideration is given both to the kinematic and dynamic boundary conditions and to the deformation of the potential-flow free surface within the boundary layer. Simplifications that are appropriate for small amplitude waves are then investigated. The flow flow field in the neighborhood of the body-boundary-layer/free-surface juncture is divided into five regions and order-of-magnitude estimated for each region are provided. Of particular interest is the body/free-surface boundary layer in the region very close to the free surface in which the free-surface boundary conditions have a significant influence. In this region, it is shown that, for laminar flow, the parameter Ak/e (where Ak is the wave-steepness parameter and e = delta/L is the nondimensional boundary-layer thickness) is an important parameter for characterizing the flow. Different solution regimes are identified depending on the magnitude of Ak/e. In particular, for Ak/e sufficiently large such that the free-surface boundary conditions have a significant influence a consistent formulation requires the solution of the partially-parabolic Navier-Stokes equations. For turbulent flow, these conclusions cannot be reached with the same degree of certainty due to the present uncertainties in turbulence modelling, especially when a free surface is present. Numerical results are provided for the idealized geometry of a combination Stokes-wave/flat-plate. Keywords: Wave/boundary layer interaction; 3-D boundary layer; Ship boundary layer.
General-Purpose Parallel Unsteady Rans Ship Hydrodynamics Code: CFDSHIP-Iowa ( Book )
1 edition published in 2003 in English and held by 1 library worldwide
CFDSHIP-IOWA is a general-purpose unsteady Reynolds-averaged Navier-Stokes CFD code that has been developed, over the past 10 years, to handle a broad range of ship hydrodynamics problems. Originally designed to support both thesis and project research in the areas of resistance and propulsion, it has been successfully transitioned to Navy and university laboratories and industry, and has recently been extended to unsteady applications such as seakeeping and maneuvering. It was developed following a modern software-development philosophy, which was based upon open source, revision control, modular coding using Fortran 90/95, liberal use of comments, and an easy to understand architecture which enables model development by users.
Numerical Simulations of the Fish Passage Facilities at Lower Granite Dam ( Book )
1 edition published in 2000 in English and held by 1 library worldwide
The purpose of these numerical simulations is to investigate possible modifications to the fish diversion facilities currently installed at Lower Granite Dam. These modifications are intended to refine the flow field just upstream of the powerhouse thereby improving the juvenile salmonid attraction potential. A pressure-based finite volume, computational fluid dynamics code was utilized to solve the Reynolds-averaged Navier-Stokes equations. The computational grids, comprising between 350,000 and 1,000,000 nodes, simulated a region encompassing the entire dam geometry as well as 5000 feet upstream. This report describes the numerical model, model boundary conditions, numerical grid and general flow field dynamics obtained from the study as well as providing recommendations for future work pertaining to numerical studies of surface collection facilities.
Ship Stern and Wake Flows: Solutions of the Fully-Elliptic Reynolds-Averaged Navier-Stokes Equations and Comparisons with Experiments ( Book )
1 edition published in 1988 in English and held by 1 library worldwide
The numerical method developed for the solution of the partially- parabolic Reynolds-averaged Navier-Stokes equations has been generalized to solve the fully-elliptic equations. This method is applied to calculate the flow over the stern and in the wake of several ship forms for which extensive data are available. The report also provides an overview of the present status of experiments and computational capabilities for such flows. Keywords: Reynolds averaged Navier Stokes, Equations, Turbulence models, Body fitted coordinates, Ship stern flows, Ship wake.
Contributions on the Problem of Ship Vibration ( Book )
1 edition published in 1972 in English and held by 1 library worldwide
Contributions to three problems of ship vibrations, (a) added masses of two-dimensional ship sections (including horizontal vibrations at a free surface), (b) three-dimensional corrections to strip theory, and (c) three-dimensional theory for vibration in a liquid, presented in a series of 16 papers, are briefly summarized. If strip theory is used, it is preferable to determine the added mass of a ship section by conformal mapping than by matching against families of forms of known added mass. If natural frequencies at higher modes are required, the three-dimensional vibration theory, which essentially replaces the added-mass vector of strip theory by an added-mass matrix, should be employed. (Author).
Free-Surface Boundary Layer and the Origin of Bow Vortices ( Book )
1 edition published in 1984 in English and held by 1 library worldwide
The boundary layer that exists due to the boundary conditions at a curved free surface of a viscous liquid ahead of a body in motion is analyzed. It is shown that surface tension and viscous effects are important and together explain the occurrence of vortices which have been observed on ship bows. The equations of the free-surface boundary layer have been derived and an integral method has been suggested for their solution.
Bed Armoring Procedures in IALLUVIAL and Application to the Missouri River ( Book )
1 edition published in 1983 in English and held by 1 library worldwide
The Conceptual model of bed 'armoring' employed in the IALLUVIAL numerical model for simulation of bed evolution in alluvial rivers has been critically assessed and refined. The approach involves use of the bed surface covered by immobile particles as a correction factor for reducing theoretical sediment transport capacity, reducing theoretical dune heights, and allocating energy losses between bed form resistance and surface roughness resistance. Computation of the armoring factor takes into account persistence in time, moving dune effects, and the stochastic nature of incipient particle motion. The report includes a review of current literature on armoring, describes the implementation of various armoring procedures in the IALLUVIAL computer program, and presents detailed results and analyses of all test performed, including several on the Missouri River between Omaha and Sioux City. Originator-supplied descriptors include: Sediment transport and Computational hydraulics.
Study of Unsteady Turbulent Boundary Layers ( Book )
1 edition published in 1983 in English and held by 1 library worldwide
A turbulent boundary layer, subjected to a free-stream velocity which changes sinusiodally in time under a zero time mean pressure gradient, is studied both experimentally and analytically. Using a two-component Laser Doppler Anemometer and a Heat Flux Gage, detailed and high quality information is obtained on the instantaneous velocity distribution and wall shear stress, respectively, at various stations. An asymptotic theory, for large Reynolds numbers, is developed for the oscillatory motion. It is valid for both boundary layers at arbitrary time-mean pressure gradients and fully developed pipe and channel flow, and is successfully applied to the present and previous available experimental information. The theory identifies two frequency parameters, in terms of which four different frequency regimes are defined. Similarity laws are identified for each one of these frequency regimes. All the experimental data have been archived on magnetic tape. (Author).
Three-Dimensional Turbulent Boundary Layer on a Body of Revolution at Incidence ( Book )
1 edition published in 1983 in English and held by 1 library worldwide
An experimental and theoretical study of three-dimensional boundary layers on bodies of revolution at incidence was conducted during the period May 1980-July 1983. This final report summarizes the technical accomplishments. Reference is made to previous reports and papers resulting from the study and some recent experimental results on the boundary layer in the plane of symmetry and the vortex formation region are presented. One of the primary objectives of this study was to develop instrumentation for the measurement of the mean flow and the Reynolds stresses in three-dimensional turbulent boundary layers, and to use these to supplement the mean-flow measurements made earlier by Ramaprian, Patel and Choi on the combination body at an incidence of 15 degrees.
On the Equations of a Thick Axisymmetric Turbulent Boundary Layer ( Book )
1 edition published in 1973 in English and held by 1 library worldwide
An examination of the Reynolds equations for axisymmetric turbulent flow where the thickness of the boundary layer is of the same order as the transverse radius of curvature of the surface shows that neither the boundary layer nor the potential flow outside it may be calculated independently of the other, owing to significant interactions between the two flow regimes. Following a discussion of various procedures for extending conventional thin boundary-layer calculation methods to treat thick axisymmetric turbulent boundary-layers, a method is proposed for the simultaneous solution of the boundary layer and the potential flow equations, allowing the two flow regimes to interact. (Author Modified Abstract).
Three-Dimensional Boundary Layers on Bodies of Revolution at Incidence ( Book )
1 edition published in 1978 in English and held by 1 library worldwide
This report summarizes the objectives and accomplishments of an experimental and theoretical investigation of the boundary layer development on bodies of revolution at incidence. The results of the flow visualization studies in laminar flow, detailed measurements in a turbulent boundary layer, and calculations of laminar as well as turbulent boundary layers using two different numerical schemes and turbulence models are reviewed to emphasize the important characteristics of separation in three dimensions.
Sediment-Budget Study for the Upper Mississippi River, GREAT-III Reach ( Book )
1 edition published in 1981 in English and held by 1 library worldwide
The sediment-budget analysis along the Upper Mississippi River was made using limited field data for the GREAT-II reach between Guttenberg, Iowa and Saverton, Missouri (Pool 11-Pool 22). This analysis resulted in a detailed pool-by-pool estimate of sediment balance, including sediment inputs and outputs on each pool boundary, and average sediment deposition (or scour) or dredging within the pool. (Author).
Coralville Reservoir Water Quality Study ( Book )
1 edition published in 1977 in English and held by 1 library worldwide
The purpose of the Coralville Reservoir Water Quality Project has been the determination of the effects of a flood control reservoir on the chemical and biological characteristics of its parent river. Samples were collected from the Iowa River upstream from the reservoir; from the top, mid-depth and bottom of the reservoir and from the Iowa River at two points downstream from the dam. From October 1975 through July 1976 samples were collected on a weekly basis and analyzed only for temperature, conductivity, turbidity, dissolved oxygen and pH. Plankton analyses were carried out monthly while all other parameters were determined on a twice monthly basis. During August and September samples were collected and analyzed twice monthly for all parameters except plankton which continued to be enumerated on a monthly basis.
Studies of axisymmetric gravity waves of finite amplitude ( Book )
1 edition published in 1960 in English and held by 1 library worldwide
ROLL DAMPING DUE TO BILGE KEELS ( Book )
1 edition published in 1958 in English and held by 1 library worldwide
An investigation of the total sediment load ( Book )
1 edition published in 1957 in English and held by 1 library worldwide