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In this work, the high-order central compact scheme is introduced to improve the accuracy of the IFLOW solver. The high-order compact filter is used to reduce non-physical oscillations. To achieve the conservation property of the scheme, the compact scheme is combined with the ENO reconstruction method. The numerical flux at the cell interface is approximated by the derivative of its primitive function which can be exactly calculated. At the boundary, ghost points are constructed. The high-order extrapolation is used to obtain values at the ghost points. Instead of using the one-sided compact scheme, the explicit central difference scheme is applied at the boundary. The results from spatial simulations of trailing vortices have shown obvious improvement in accuracy., Presented at AFOSR International Conference on DNS/LES (3rd) held at Univ. of Texas, Arlington, TX on 5-9 Aug 2001. Prepared in collaboration with Dept. of Mathematics, Univ. of Texas, Arlington, TX. This article is from ADA412801 DNS/LES Progress and Challenges. Proceedings of the Third AFOSR International Conference on DNS/LES

The standard ship performance prediction method used at the David Taylor Model Basin (DTMB) is compared to the method proposed by the 15th International Towing Tank Conference in 1978 (ITTC-78).

Extracted version of report dated 21 Jan 63.

This project involved the measurement of the loading, strain, deformation, and damage to the hull of a submarine-like target resulting from planned near lethal attack during Shot umbrella. It also involved the measurement of hull strains in an operating submarine in simulated attack positions during Shots Wahoo and Umbrella. The objectives established for this project were: (1) to determine the range for lethal hull damage to a submarine- like target under attack in shallow water by an antisubmarine nuclear weapon; (2) to study the process of hull damange to a submerged target for correlation with observed pressure and existing approximate theories and empirical formulas; and (3) to determine the response of the hull of a submarine in simulated attack position in both deep and shallow water., Extracted version of report dated 15 Dec 1960.

The shock loading in ships and the response of shipboard machinery were measured during Shots Wahoo and Umbrella to: (1) determine safe- and shock- damage ranges, particularly with respect to shipboard machinery and equipment, for delivery of antisubmarine nuclear weapons by destroyers and submarines; (2) determine the intensity and character of the shock motions on a submarine and on a merchant ship under quasi-lethal attack by and underwater nuclear explosion; and (3) acquire shock-motion data and correlate such data with other measurements and with theory in order to extrapolate the results to other attack geometries. Conclusions include: (1) The shock damaging ranges for ships from underwater explosions depend greatly on the design and condition of the machinery and equipments as well as on charge size, burst depth, water depth, and the like. (2) Immobilization ranges for a destroyer are given as horizontal ranges from surface zero to the center of the ship. (3) Temperature gradients in the water increase or decrease the damage ranges., Extracted version of report dated 30 Sep 1961.

An analysis is developed to account for the effects of imperfections on the collapse strength of spherical shells. The analysis is empirical but is based on an engineering evaluation of recent tests of near-perfect deep spherical shells and spherical caps. Sixty-two models were machined with local thin spots and flat spots and subjected to external hydrostatic pressure. The analysis is in good agreement with experimental results despite the severity of imperfections selected to test the analysis. The limitations of the analysis are discussed and curves showing the relationship between out of roundness and local radius are presented to aid the design engineer in establishing acceptable tolerance limits for fabrication of spherical shells.

Two accurately machined hemispherical shells bound by ring-stiffened cylinders designed to provide ideal edge conditions were tested under hydrostatic pressure to determine the elastic buckling strength of near-perfect deep spherical shells. Ratios of experimental collapse pressure to the pressure calculated by using the classical small-deflection theory of 0.73 and 0.90 were obtained. The ratio of 0.90 is considerably higher than the ratios obtained in previous tests recorded in the literature. Since these models had small, unavoidable imperfections, the experimental results lend considerable support to the validity of the small-deflection analysis for the elastic buckling strength of initially perfect spheres.

General resistance tests of TMB Model 4667 were conducted to determine the performance characteristics of one of a series of hulls which might be adaptable for use with hydrofoils. Resistance, trimming moment, and wetted length were measured for several load, trim, and speed conditions. All data are presented in nondimensional form for use in comparing hull forms and calculating takeoff performance.

The utilization of a design approach for a planing boat similar to that followed in the design of a hydrofoil boat or an airplane leads to a new, more efficient type of planing boat configuration. The lift-drag ratio of the new configuration is approximately 50 percent greater than that of the conventional stepless planing boat.

A planing surface with 15-deg deadrise, circular-arc camber, and a moderate amount of trailing edge sweep was designed as the main lifting surface for an existing experimental stepped planing boat. A model of the planing surface was then built and tested in the towing basin. The test results indicate that the lift/drag ratio of the main planing surface of the boat will be increased 10 percent by utilization of this design. Also, the performance in head seas should be significantly improved since the cambered surface will develop the necessary lift at approximately one-half the forebody angle of attack at which the boat now operates.

Data on the performance characteristics of a planing float and of a displacement float, originally designed for supporting a catenary loop of minesweeping cable, are analyzed. The planing float was a prototype of the TMB planing float and was constructed of welded steel. The displacement float was in the form of a body of revolution and was constructed of balsa wood. The data on the planing float in the planing regime are compiled into a single nondimensional relationship between drag, total load, and speedlength ratio. The characteristics of the balsa-wood displacement float are also presented in nondimensional form as a family of curves of drag coefficient plotted on speed- length ratio with a load coefficient as parameter.

Experiments were made to determine the effects on planing boat resistance of several configurations of longitudinal bottom spray strips. It was found that such strips extending aft from the bow about 70% of the hull length decreased the resistance somewhat at high speed but increased the resistance at low speed. The performance was noticeably improved by sharpening the edges of the spray strips. An experiment was also made with bottom spray strips extending only forward of the high-speed stagnation line. This arrangement gave a 6% reduction in resistance at high speed with no increase in resistance at low speed.

An unswept 12-percent-thick wing panel (NACA 0012 section) was tested with a wedge protruding from the blunt leading edge to determine if wing drag could be reduced and lift-to-drag ratio improved at a supersonic airspeed (Mach number 1.87). The wing and wedge were also tested at low subsonic airspeeds to determine if a slat effect existed which would increase maximum lift. At the supersonic airspeed, the wedge reduced the drag of the plain wing by as much as 29 percent at low angles of attack. At higher angles, this drag reduction vanished but the wedge still increased the maximum ratio of lift to drag by as much as 20 percent. At low speeds, a wedge slat increased maximum lift by as much as 54 percent. A small cambered airfoil slat (with a somewhat larger chord than the wedge) was able to increase maximum lift by 72 percent.

The effects of austenitizing, tempering temperatures times on fully quenched low- and high-chemistry HY-80 steels were investigated. Correlation procedures were established for relating notch-brittleness properties to tensile strength for a given Charpy V-notch fibrous fracture appearance. The results indicate that Charpy V-notch transition temperatures increase with increasing austenitizing and decreasing tempering temperatures. For fully quenched HY-80 steels, the optimum Charpy V-notch impact fibrous transition temperatures are attained for the 100,000psi-yield-strength level.

A small-deflection analysis is developed for the elastic interbay buckling of ring-stiffened cylindrical shells in which the influence of the rings on deformations before an during budkling is considered. Tests were carried out with a machined, ring-stiffened cylinder (BR-4B) subjected to external hydrostatic pressure Collapse was initiated by elastic asymmetric buckling of the shell. Strain easurements taken during the test demonstrated that the South ell method of determining buckling strength nondestructively is applicable in the case of interbay buckling. The results of this and three other tests of machined cylinders are in good agreement with the theory. While the Von Mises theory is inaccurate for closely spaced rings, its continued application for estimating elastic buckling strength is probably justified since it is always conservative and can be represented in a simple form.

A series of small machined aluminum models were collapsed under external hydrostatic pressure to study the inelastic buckling of near-perfect ring-stiffened cylinders made of strain-hardening materials. The predominant modes of failure were general instability and axisymmetric shell buckling. Comparisons of test results with the analyses of Lunchick, Krenzke, and Kiernan show promising correlation but additional data would be needed for a complete evaluation. High bending stresses near frames did not noticeably affect axisymmetric shell buckling strength. The presence of frame fillets, however, caused a significant increase in general instability strength although bending stresses in the absence of fillets were relatively low.

A theoretical derivation is given for elastic and plastic buckling of stiffened circular cylindrical shells under external hydrostatic pressure. The theory accounts for variable shell stresses, as influenced by the circular stiffeners, and critical buckling pressures are obtained for simple support conditions at the shell-frame junctures. Methods are given for the determination of collapse pressures for both elastic and plastic asymmetric buckling by interation and numerical minimization. The theory is applicable to shells made either of strain-hardening or elastic-perfectly plastic materials. Using the theory, it is shown that a variation in stiffener size can change the buckling pressures. Test data from high-strength steel and aluminum cylinders are presented which show theoretical and experimental collapse pressures to agree within approximately 6 per cent.

Experimental and theoretical studies of the type 5M10,000-H rubber resilient mount assembly consisting of a compression and shear mount and snubber were conducted to determine its performance under shock loading. In the experimental study, the mount assembly (supporting a rigid test mass) was installed on the Floating Shock Platform and subjected to a series of five shock tests. The experimental data were analyzed and dynamic force-deflection curves were obtained. Parallel theoretical studies were conducted. A simple mathematical model combining springs and dashpots was used to represent the response of the mounts under vertical shock loading. Theoretical dynamic force deflection curves obtained from this system showed good agreement with the experimental data. Findings of the experimental and theoretical studies led to the conclusion that dynamic force-deflection curves must be used in calculations of the shock response of supported equipment.

The report evaluates the effects of strength level, Charpy V-notch energy, prestraining, prestraining and stress relieving, and austenitizing temperature on the fatigue life of a fully quenched HY-80 steel composition. The fatigue data developed indicate that the designer would have to be cautious when going to higher strength steel when using a safety factor which is considered satisfactory for lower strength steels, i.e., if higher strength steels are to be used, larger safety factors are necessary to obtain a comparable fatigue life. The limited data presented on experimental HY-150 steels indicate that caution will have to be exercised in evaluating large specimen fatigue data.

The paper presents a method for calculation the instantaneous pressure, velocity, acceleration, and radius associated with the collapse of a spherical gas-filled cavity in an infinite compressible liquid. The method is an independent approach which makes use of Hamming's technique to numerically integrate Gilmore's differential equations which describe the collapse. Included is a computer program which will perform the necessary calculation on a IBM 7090/1401 digital computer. It may be inferred that the peak shock wave pressure is significantly reduced by a decrease in ambient pressure, and increase in internal pressure, and/or a variation of the specific heat ratio by proper selection of the gas. Control of the last two parameters can be investigated as a possible means of protecting glass spheres against sympathetic implosion in multiple sphere buoyancy systems.

Details are given on the general subject of ship vibration, including both the structural and hydrodynamic phases of the subject. Brief mention is also made of vibration in the propulsion system. Procedures for dealing with the problem of ship vibration in the design stage are suggested. An introduction to hydroelasticity is included.

Expressions are given for the complete added mass effect for any rigid body moving in any manner in an ideal fluid. The expressions give the force and moment acting on the body in terms of 21 added mass derivatives. These derivatives are the maximum number that are independent for a Cartesian set of body axes. Reduced expressions are also given for a finned prolate spheroid with the origin of the body axes located at some point on the axis of revolution. Theoretical values of the added mass derivatives are given for an ellipsoid and a prolate spheroid when the reference axes are principal axes for an origin located at the center of the ellipsoid or spheroid. The added mass effect for a stationary body in an accelerating fluid is also described.

Various phases of an underwater explosion are described. Nomograms are given for characteristics parameters of the shock wave and the bubble pulsation. Possible effects of the water surface and the sea bottom are discussed. Characteristic ship-response phases are reviewed and explained. They are demonstrated by actual examples of hull response and hull damage. The shipboard shock environment to which any installation aboard a ship is subjected is presented, and typical cases of shock damage are shown. The significance of the study of ship response to underwater explosions is reviewed. Generalization of the few controlled explosion tests against ships becomes possible by application to loading and response theories. The foundation is thus laid for increasing the combat reliability of ships and their endurance under attack., Reprint of paper presented at the Annual Meeting, Society of Naval Architects and Marine Engineers, 16-17 Nov 61, New York, N. Y.

Four existing models of planing craft were retested at the Taylor Model Basin's "standard condition" for planing boat models. The test results for each model are presented in a design data sheet. The data are compared to show the effects of differences in hull form. These comparisons are independent of differences in hull loading, in LCG location, or in size of boat. Auxiliary graphs are included to assist in making estimates of speed and power for new designs.

Complete expressions are given for the forces and moments acting on a submerged body because of gravitational attraction on the mass of the body and buoyancy force acting on the body boundary. The variations of the forces and moments with changes in angular attitude of the body are discussed in detail. The relationship of these variations to the phenomenon of metacentric stability is described.

Trans. no. 6 from Stodola's Festschrift, Zurich, pp. 418-430, 1929.

An investigation was conducted in the Taylor Model Basin 8- by 10- foot subsonic, atmospheric Wind Tunnel 2 to determine the drag coefficient of man. Tests were made at several yaw angles with subjects of various sizes in five body positions: standing, sitting supine, and two squat positions. Data were obtained for the subjects in both the clothed and nude conditions. A parameter was formulated from the available physical characteristics of the subjects tested and all coefficients were based on this. Drag coefficients were obtained which should be reliable in predicting drag forces on men of average stature under a variety of conditions. Lift, side force, and moments were also obtained which indicate relative trends of motion for each position.

Following a brief review of prior work on wave resistance of bodies of revolution carried out by Havelock and Weinblum a discussion is presented of the approximate relations between the shape of sectional-area curves and of hydrodynamic irregularity distributions. The latter are expressed by polynomials, which lend themselves to an evaluation of the basic resistance integrals by computing intermediate integrals. Values of the functions thus obtained are tabulated in an appendix. These functions are then used to calculate the resistance of some simple bodies of revolution. Also investigated is how the resistance is influenced by asymmetry with respect to midship section. Distributions leading to bodies of least wave resistance are calculated, assuming rather severe restrictions. A rather complete set of resistance curves is given for an important family of bodies.

A 12-percent-thick section (NACA 0012) wing panel with leading-edge spikes was tested at a Mach number of 1.88 to determine whether the wing drag could be reduced in such a manner that the ratio of maximum lift coefficient at landing speed to minimum drag coefficient at high speed would compare favorably with the ratio obtained from a thin, high-speed wing. A 6-percent-thick high- speed wing section (NACA 65-006) was tested to provide comparison data for the thick wing. A drag reduction of 20 percent (compared to the plain wing) was obtained when spikes protruded forward ten times the leading-edge radius. This drag reduction was obtained with a spike spacing of 5 percent of the chord. This drag reduction was not enough to make the ratio of maximum lift coefficient to minimum drag coefficient for the thick wing compare favorably with that for the thin wing.

From the theory of wave resistance various deductions can be made on the resistance of bodies of revolution immersed at finite depth; especially, favorable 'optimum' forms can be developed for given Froude numbers. By testing three models it is shown that theoretical results agree well, qualitatively and even quantitatively with the experimental results, if a 'phase displacement' is ignored. The theory can be used up to minimum immersions of f = 2b for a length/ diameter ratio L : B = a : b = 8; for a first orientation even f = b can be admitted as long as full and short bodies are excluded., Trans. from Versuche ueber den Wellenwiderstand Getauchter Rotationskoerper, Preussische Versuchsanstalt fuer Wasserbau und Schiffbau. Mitteilungen (Germany East and West) n.p., 1936. Translated by G. Weinblum and R. Widmer. Text in English.

Ground level air blast pressures were measured by the David Taylor Model Basin on the main blast line and in aircraft parking areas for Shots 2, 3, and 4. The purpose of these measurements was two-fold: (a) to provide blast pressure data at specific locations of especial interest to Program 3 in correlating damage to aircraft on the ground and (b) to provide blast pressure data suitable for a check of azimuth symmetry and for comparison with data obtained by other activities participating in the TUMBLER-SNAPPER series of tests. Eight interferometer (Buck) gages and eight David Taylor Model Basin capacitance gages were used in the operation. Reproductions of the recorded pressure-time curves are placed in the main body of the report. In addition, peak pressure values, positive and negative phase durations, and positive and negative impulse values are tabulated for each shot. Self-contained gage stations were used to make these measurements, i.e., recordings were made at each gage location rather than at a central recording station. This technique appears to be quite successful and requires no costly cable trenches. The development of more compact apparatus specifically designed for mounting in a small cylindrical housing underground is desirable.

Subsonic wind-tunnel test results of a tandem wing aircraft configuration are given. Conventional longitudinal tests out of ground effect, and similar tests in ground effect, employing the ground board test technique, were conducted on the configuration. Test variables included height above the surface, forward and aft wing incidence angles, angle of attack, and center-of- gravity location. (Author), Bureau of Naval Weapons (Problem Assignment 1-34-52).

A number of research organizations have been playing a key role in developing the structures and materials technologies required for designing and fabricating the pressure hulls, a controlling factor, of these deep-submergence vehicles. This paper summarizes some significant theoretical and experimental findings, and their application, which have resulted from research and development efforts during the past several years. Specifically, recent developments in shell-like structures, e.g., cylindrical, spherical, and spheroidal, and the impact of new hull materials on structural concepts and design are discussed.

The predominant forces on a mast projecting from a submerged submarine through the surface are steady drag, periodic lift, and wave impact. As the natural frequency of vibration of the mast-radome configuration under consideration is in the vicinity of the vortex shedding frequency, a catastrophic instability should be expected. Since the function of the radome at the top of the mast is to protect the encapsulated instruments, any large deflection of the dome could endanger the contents. The forces on the dome due to drag and breaking waves are estimated for particular operating conditions, numerical values being presented in tabular form for the force distribution over the dome. Also given is the frequency of occurrence of the significant wave for these conditions. The impact force prevails over all others and represents the major obstacle to successful operation of the system in high seas. Pertinent criteria are established to serve as guidelines for the design of the system.

Equations are derived for the pressure rise in a terminal room or chamber due to the propagation through a duct system of a transient pressure from an external blast pressure wave. Numerical values for the peak pressure in the chamber are given in terms of the parameters of the blast pressure wave and the characteristics of the duct-chamber system. The calculation of the relevant characteristics of the duct-chamber system is described and illustrated.

A procedure for calculating the spindle torque and for determining the optimum spindle axis location of a controllable-pitch propeller at design conditions is presented. From the blade geometry and theoretical pressure distribution the hydrodynamic and centrifugal forces acting on the blade are obtained, and from the distribution of these forces the spindle torque is calculated. The optimum spindle axis location is then determined by an iteration process. An example is included to illustrate the procedure.

An 0 Type, Size 5, Reinforced-plastic Minesweeping Float was designed and fabricated at the David Taylor Model Basin. Tests were conducted in the circulating-water channel to determine the net buoyancy, lift, drag, and towing characteristics. Tests to verify towing characteristics were also made using a small boat in the Chesapeake Bay. After modifications to towpoint and control surfaces, the float towed in a stable manner over the speed range of 0 to 7 knots. It is concluded that a Size 5 Minesweeping Float fabricated from plastic will have satisfactory towing characteristics and will allow a substantial reduction in the handling weight.

This report describes a method for obtaining digital computer solutions for the excitation forces on and transient response of a ship subject to (hydrodynamic) slam when certain basic data are obtained by computation rather than by measurement. The method is based on a theory shown in TMB Report 1511 to be in good agreement with experiment for a particular application.