Journal articles on the topic 'Nonlinear hydrodynamic analysis'
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1
Léger, P., and S. S. Bhattacharjee. "Seismic fracture analysis of concrete gravity dams." Canadian Journal of Civil Engineering 22, no. 1 (February 1, 1995): 196–201. http://dx.doi.org/10.1139/l95-018.
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Nonlinear seismic analyses of a 90 m high concrete gravity dam, assumed to be located in eastern Canada, have been conducted using a smeared crack finite element model. Reduced frequency-independent added matrices have been used to represent the hydrodynamic and foundation interaction effects. Parametric analyses have been performed to assess the effects of the initial conditions induced by severe winter temperature, and the effects of hydrodynamic and foundation interaction mechanisms, on the nonlinear seismic behaviour of the dam. Key words: gravity dams, nonlinear seismic response, finite element, crack propagation.
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Viana, Carlos Alberto Alves, Diogo Stuani Alves, and Tiago Henrique Machado. "Linear and Nonlinear Performance Analysis of Hydrodynamic Journal Bearings with Different Geometries." Applied Sciences 12, no. 7 (March 22, 2022): 3215. http://dx.doi.org/10.3390/app12073215.
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In rotor dynamics, a traditional way of representing the dynamics of hydrodynamic bearings is using stiffness/damping coefficients. It is thus necessary to carry out a linearization of hydrodynamic forces around the shaft’s equilibrium position. However, hydrodynamic bearings have highly nonlinear nature, depending on operating conditions. Therefore, this paper discusses the applicability of these linear/nonlinear approaches using a computational model of the rotating system, where the finite element method is used for rotor modelling and the finite volume method for bearing calculation. The main goal is to investigate the boundaries for linear approximation of the hydrodynamic forces present in lobed hydrodynamic bearings, with the system operating under high loading conditions. Several numerical simulations were performed varying preload parameter and rotating speed. A comparison of the system’s responses, in time domain (shaft orbits) and frequency domain (full spectrum), is made for linear and nonlinear models. Results showed that trilobed bearings are more susceptible to nonlinearities, even in situations of smaller vibration amplitudes, while elliptical bearings are sensitive only under larger vibration amplitudes. These analyses are of great importance for mapping the influence of nonlinearities in different types of lobed hydrodynamic bearings with fixed geometry, varying the preload parameter to verify the influence on the system’s dynamic response. This study is important and serves as the basis for cases of monitoring and fault diagnosis (in the field of structural health monitoring) since it is crucial to distinguish what would be a fault signature or a standard nonlinear effect created by the use of hydrodynamic bearings.
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Shao, Song Shi, Jiong Sun, and Kai Liu. "Bifurcation Analysis for Sailing Stability of Autonomous Underwater Vehicle." Applied Mechanics and Materials 44-47 (December 2010): 1682–86. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.1682.
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There are several nonlinear elements in the equations of Autonomous Underwater Vehicle(AUV) movements. It is difficult to deal nonlinear problem with traditional methods. A hydrodynamic parameter interference is chosen as bifurcation parameter at first. Then the sailing stability of AUV with proportional-derivative controller is analysed by bifurcation theory. The center manifold theory is used to get the expression of system state parameters. And the Hopf bifurcation of system is analysed. The result is verified by numerical simulations. It shows that the hydrodynamic parameter’s changing will bring Hopf bifurcation for depthkeeping saiiling. And the range of hydrodynamic parameter value that insures AUV sailing stability is given.
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Deguchi, Kengo. "High-speed shear-driven dynamos. Part 1. Asymptotic analysis." Journal of Fluid Mechanics 868 (April 10, 2019): 176–211. http://dx.doi.org/10.1017/jfm.2019.178.
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Rational large Reynolds number matched asymptotic expansions of three-dimensional nonlinear magneto-hydrodynamic (MHD) states are the concern of this contribution. The nonlinear MHD states, assumed to be predominantly driven by a unidirectional shear, can be sustained without any linear instability of the base flow and hence are responsible for subcritical transition to turbulence. Two classes of nonlinear MHD states are found. The first class of nonlinear states emerged out of a nice combination of the purely hydrodynamic vortex/wave interaction theory by Hall & Smith (J. Fluid Mech., vol. 227, 1991, pp. 641–666) and the resonant absorption theories on Alfvén waves, developed in the solar physics community (e.g. Sakurai et al. Solar Phys., vol. 133, 1991, pp. 227–245; Goossens et al. Solar Phys., vol. 157, 1995, pp. 75–102). Similar to the hydrodynamic theory, the mechanism of the MHD states can be explained by the successive interaction of the roll, streak and wave fields, which are now defined both for the hydrodynamic and magnetic fields. The derivation of this ‘vortex/Alfvén wave interaction’ state is rather straightforward as the scalings for both of the hydrodynamic and magnetic fields are identical. It turns out that the leading-order magnetic field of the asymptotic states appears only when a small external magnetic field is present. However, it does not mean that purely shear-driven dynamos are not possible. In fact, the second class of ‘self-sustained shear-driven dynamo theory’ shows a magnetic generation that is slightly smaller in size in the absence of any external field. Despite its small size, the magnetic field causes the novel feedback mechanism in the velocity field through resonant absorption, wherein the magnetic wave becomes more strongly amplified than the hydrodynamic counterpart.
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Ghesmat, Karim. "In-Situ, Solvent-Assisted Gravity Drainage of Bitumen: Nonlinear Numerical Analysis." SPE Journal 19, no. 01 (June 17, 2013): 109–21. http://dx.doi.org/10.2118/165579-pa.
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Summary The use of condensing solvents, especially propane vapor, has been proposed for the low-temperature recovery of bitumen by gravity drainage. A full numerical analysis of such a process is presented. A hybrid spectral/finite-difference method was implemented to solve equations simultaneously. The results show that the hydrodynamics of a miscible front was highly dependent on the characteristics of the porous medium and also on the properties of the miscible fluid. As a significant factor, the dependency of the production flow rate on the thickness of the porous medium was measured. The order of dependency was found to be a function of time and cannot be considered as a constant. Hydrodynamic dispersion was also found to decrease this dependency. More-detailed results, along with quantitative analyses, are also discussed to indicate how the hydrodynamics was influenced by other porous-medium characteristics and fluid properties, such as dissolution rate and molecular diffusion.
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Bhattacharyya, S. K., and M. R. Haddara. "Parametric Identification for Nonlinear Ship Maneuvering." Journal of Ship Research 50, no. 03 (September 1, 2006): 197–207. http://dx.doi.org/10.5957/jsr.2006.50.3.197.
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A parametric identification method for the estimation of hydrodynamic derivatives embedded in the nonlinear steering equations for ship maneuvering in calm seas is presented. The models developed for identification involve determination of constant, "low-frequency" hydrodynamic derivatives. The method is robust, noniterative, and computationally light, and it requires no starting estimates. In this method, the time domain operations are converted to linear operations in the frequency domain. The responses of the ship in a few standard maneuvers have been simulated in the numerical examples, and the proposed method is applied to these data in order to estimate the hydrodynamic derivatives for a few "identifiable" combinations.
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Qiu Hai-Jian, Hu Yu-Lu, Hu Quan, Zhu Xiao-Fang, and Li Bin. "Nonlinear theory considering harmonic interaction using Eulerian hydrodynamic analysis." Acta Physica Sinica 67, no. 8 (2018): 088401. http://dx.doi.org/10.7498/aps.67.20180024.
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Deguchi, Kengo. "High-speed shear-driven dynamos. Part 2. Numerical analysis." Journal of Fluid Mechanics 876 (August 8, 2019): 830–58. http://dx.doi.org/10.1017/jfm.2019.560.
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This paper aims to numerically verify the large Reynolds number asymptotic theory of magneto-hydrodynamic (MHD) flows proposed in the companion paper Deguchi (J. Fluid Mech., vol. 868, 2019, pp. 176–211). To avoid any complexity associated with the chaotic nature of turbulence and flow geometry, nonlinear steady solutions of the viscous resistive MHD equations in plane Couette flow have been utilised. Two classes of nonlinear MHD states, which convert kinematic energy to magnetic energy effectively, have been determined. The first class of nonlinear states can be obtained when a small spanwise uniform magnetic field is applied to the known hydrodynamic solution branch of plane Couette flow. The nonlinear states are characterised by the hydrodynamic/magnetic roll–streak and the resonant layer at which strong vorticity and current sheets are observed. These flow features, and the induced strong streamwise magnetic field, are fully consistent with the vortex/Alfvén wave interaction theory proposed in the companion paper. When the spanwise uniform magnetic field is switched off, the solutions become purely hydrodynamic. However, the second class of ‘self-sustained shear-driven dynamos’ at the zero external magnetic field limit can be found by homotopy via the forced states subject to a spanwise uniform current field. The discovery of the dynamo states has motivated the corresponding large Reynolds number matched asymptotic analysis in the companion paper. Here, the reduced equations derived by the asymptotic theory have been solved numerically. The asymptotic solution provides remarkably good predictions for the finite Reynolds number dynamo solutions.
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Isaacson, Michael, and John Baldwin. "Moored structures in waves and currents." Canadian Journal of Civil Engineering 23, no. 2 (April 1, 1996): 418–30. http://dx.doi.org/10.1139/l96-046.
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The present paper provides a brief review of the analysis of moored floating structures in waves and currents. A hydrodynamic analysis is required in order to predict wave and current effects on floating structures, and corresponding numerical models for determining transmitted and reflected wave heights, added masses, damping coefficients, and wave exciting forces are summarized. A mooring analysis is required in conjunction with the hydrodynamic analysis in order to calculate the restraint provided by the mooring system, as well as the structure motions, mooring line and anchor loads, and mooring line configurations. Various aspects of static, dynamic, and nonlinear responses are discussed and illustrated with example applications. Key words: coastal engineering, currents, floating structures, hydrodynamics, mooring forces, ocean engineering, wave forces, waves.
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Pacuraru, Florin, Leonard Domnisoru, and Sandita Pacuraru. "On the Comparative Seakeeping Analysis of the Full Scale KCS by Several Hydrodynamic Approaches." Journal of Marine Science and Engineering 8, no. 12 (November 25, 2020): 962. http://dx.doi.org/10.3390/jmse8120962.
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The main transport channel of the global economy is represented by shipping. Engineers and hull designers are more preoccupied in ensuring fleet safety, the proper operation of the ships, and, more recently, compliance with International Maritime Organization (IMO) regulatory incentives. Considerable efforts have been devoted to in-depth understanding of the hydrodynamics mechanism and prediction of ship behavior in waves. Prediction of seakeeping performances with a certain degree of accuracy is a demanding task for naval architects and researchers. In this paper, a fully numerical approach of the seakeeping performance of a KRISO (Korea Research Institute of Ships and Ocean Engineering, Daejeon, South Korea) container ship (KCS) container vessel is presented. Several hydrodynamic methods have been employed in order to obtain accurate results of ship hydrodynamic response in regular waves. First, an in-house code DYN (Dynamic Ship Analysis, “Dunarea de Jos” University of Galati, Romania), based on linear strip theory (ST) was used. Then, a 3D fully nonlinear time-domain Boundary Element Method (BEM) was implemented, using the commercial code SHIPFLOW (FLOWTECH International AB, Gothenburg, Sweden). Finally, the commercial software NUMECA (NUMECA International, Brussels, Belgium) was used in order to solve the incompressible unsteady Reynolds-averaged Navier–Stokes equation (RANSE) flow at ship motions in head waves. The results obtained using these methods are represented and discussed, in order to establish a methodology for estimating the ship response in regular waves with accurate results and the sensitivity of hydrodynamical models.
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Barna, Imre F., Mihály A. Pocsai, and L. Mátyás. "Self-Similarity Analysis of the Nonlinear Schrödinger Equation in the Madelung Form." Advances in Mathematical Physics 2018 (October 1, 2018): 1–5. http://dx.doi.org/10.1155/2018/7087295.
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In the present study a particular case of Gross-Pitaevskii or nonlinear Schrödinger equation is rewritten to a form similar to a hydrodynamic Euler equation using the Madelung transformation. The obtained system of differential equations is highly nonlinear. Regarding the solutions, a larger coefficient of the nonlinear term yields stronger deviation of the solution from the linear case.
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Yim, S. C. S., and S. Narayanan. "Modeling and Identification of a Nonlinear SDOF Moored Structure, Part 2—Comparisons and Sensitivity Study." Journal of Offshore Mechanics and Arctic Engineering 126, no. 2 (May 1, 2004): 183–90. http://dx.doi.org/10.1115/1.1710874.
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A system-identification technique based on the Reverse Multiple-Input/Single-Output (R-MI/SO) procedure is applied to identify the parameters of an experimental mooring system exhibiting nonlinear behavior. In Part 1, two nonlinear small-body hydrodynamic Morison type formulations: (A) with a relative-velocity (RV) model, and (B) with an independent-flow-field (IFF) model, are formulated. Their associated nonlinear system-identification algorithms based on the R-MI/SO system-identification technique: (A.1) nonlinear-structure linearly damped, and (A.2) nonlinear-structure coupled hydrodynamically damped for the RV model, and (B.1) nonlinear-structure nonlinearly damped for the IFF model, are developed for an experimental submerged-sphere nonlinear mooring system under ocean waves. The analytic models and the associated algorithms for parametric identification are described. In this companion paper (Part 2), we use the experimentally measured input wave and output system response data and apply the algorithms derived based on the multiple-input/single-output linear analysis of the reverse dynamic systems to identify the system parameters. The two nonlinear models are examined in detail and the most suitable physical representative model is selected for the mooring system considered. A sensitive analysis is conducted to investigate the coupled hydrodynamic forces modeled by the Morison equation, the nonlinear stiffness from mooring lines and the nonlinear response. The appropriateness of each model is discussed in detail.
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Roy, Sukesh, James R. Gord, Jia-Chen Hua, and Gemunu H. Gunaratne. "Robust-mode analysis of hydrodynamic flows." International Journal of Modern Physics B 31, no. 10 (April 20, 2017): 1742007. http://dx.doi.org/10.1142/s0217979217420073.
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The emergence of techniques to extract high-frequency high-resolution data introduces a new avenue for modal decomposition to assess the underlying dynamics, especially of complex flows. However, this task requires the differentiation of robust, repeatable flow constituents from noise and other irregular features of a flow. Traditional approaches involving low-pass filtering and principle components analysis have shortcomings. The approach outlined here, referred to as robust-mode analysis, is based on Koopman decomposition. Three applications to (a) a counter-rotating cellular flame state, (b) variations in financial markets, and (c) turbulent injector flows are provided.
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Li, Fu Rong, and Zhi Hua Wang. "Hydrodynamic Pressure Effect Analysis of Double-Column Pier in Deep Water under Earthquake Actions." Advanced Materials Research 255-260 (May 2011): 3697–701. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3697.
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Taking the double-column pier as the research project, based on ABAQUS finite software, using the added water mass to consider the hydrodynamic pressure effect, considering the nonlinear of the soil and the concrete, building the hydrodynamic pressure effect model analysis of double-column bridge pier in deep water under earthquake actions, analyzing the hydrodynamic pressure effect on the relative displacement, acceleration, shear force, moment responses of pier and its hydrodynamic pressure coefficient under the earthquake. The results show that the earthquake hydrodynamic pressure changes the seismic responses characters of the pier, and increases the relative displacement and acceleration of pier top, and also increases the internal force of pier bottom. It is necessary to consider the hydrodynamic pressure effect in the bridge seismic design for comply with the actual situation better.
15
Wu, MingKang, and Torgeir Moan. "Linear and Nonlinear Hydroelastic Analysis of High-Speed Vessels." Journal of Ship Research 40, no. 02 (June 1, 1996): 149–63. http://dx.doi.org/10.5957/jsr.1996.40.2.149.
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A linear formulation of ship hydroelasticity is presented. Appropriate body boundary conditions of flexible modes are obtained and the hydroelastic version of high-speed strip theory is established. A nonlinear time-domain simulation method is also presented. The total response is decomposed into linear and nonlinear parts. The linear part is evaluated using appropriate linear potential-flow theory and the nonlinear part comes from the convolution of the impulse response functions of linear ship-fluid system and the nonlinear hydrodynamic forces. Four high-speed vessels with different ship lengths but with similar body plan and internal structural arrangement are used as examples. The calculations of midship bending moments are carried out at different forward speeds and head sea states. The results show that the hydroelastic effect in linear extreme responses is insignificant and that the hydrodynamic damping plays a leading role in the flexible modes when the dynamic amplification of ship hull becomes important. The results also indicate that strong nonlinearity is the most prominent feature of high-speed vessels even in the moderate sea state and must be taken into account. The nonlinear influences are more remarkable in ships at large Froude numbers than in those at small ones, and more important in sagging moment than in hogging moment.
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Choy, F. K., M. J. Braun, and Y. Hu. "Nonlinear Transient and Frequency Response Analysis of a Hydrodynamic Journal Bearing." Journal of Tribology 114, no. 3 (July 1, 1992): 448–54. http://dx.doi.org/10.1115/1.2920904.
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The traditional approach is to characterize the behavior and performance of fluid film hydrodynamic journal bearings by means of linearized bearing analysis. The objective of this paper is to examine the nonlinear characteristics of the said journal bearing. Results based on bearing stiffness characteristics, steady and transient vibration orbits, and frequency response functions obtained from both linear and nonlinear bearing simulations are compared with each other. Conclusions are drawn from the results obtained from a prototypical bearing configuration used as an example in this analysis.
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Goldsworthy, M. P., F. Green, and H. Hora. "A new hydrodynamic analysis of double layers." Laser and Particle Beams 5, no. 2 (May 1987): 269–86. http://dx.doi.org/10.1017/s0263034600002767.
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A Genuine two-fluid model of plasmas with collisions permits the calculation of dynamic electric fields and double layers inside plasmas including oscillations and damping. For the first time a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser produced plasmas showing very high dynamic electric fields in nonlinear force produced cavitons and inverted layers, in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. We find the rotation of plasmas in magnetic fields and a new second harmonic resonance. Explanation of inverted double layers, second harmonic emission from laser produced plasmas, and laser acceleration of charged particles by the very high fields of the double layers is given.
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Kim, Boo-Ki, and Michael M. Bernitsas. "Effect of Memory on the Stability of Spread Mooring Systems." Journal of Ship Research 43, no. 03 (September 1, 1999): 157–69. http://dx.doi.org/10.5957/jsr.1999.43.3.157.
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The importance of including the hydrodynamic memory effect in modeling and analysis of spread mooring systems (SMS) is assessed based on the design methodology for mooring systems developed at the University of Michigan. The memory effect is modeled by the hydrodynamic radiation forces expressed in terms of added mass at infinite frequency and convolution integrals of impulse response functions. The convolution integrals, which are explicit functions of time, are converted to autonomous excitation by the method of extended dynamics. For a given SMS configuration, nonlinear stability and bifurcation theory are used to produce catastrophe sets in the parametric design space separating regions of qualitatively different system dynamics. This approach reveals the complete picture of nonlinear phenomena associated with system dynamics and eliminates the need for extensive simulations. Catastrophe sets are developed in several parametric design spaces, providing fundamental understanding of the memory effects on SMS nonlinear dynamics. The mathematical model is based on the slow-motion maneuvering equations in the horizontal plane, including hydrodynamic memory effect and third-order quasi-steady hydrodynamic forces. Mooring lines are modeled by synthetic fiber ropes attached to surface terminals and deep-water catenary chains with touchdown and nonlinear drag. Environmental loads consist of time-independent current, wind, and mean wave drift forces.
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Poguluri, Sunny Kumar, Dongeun Kim, and Yoon Hyeok Bae. "Hydrodynamic Analysis of a Multibody Wave Energy Converter in Regular Waves." Processes 9, no. 7 (July 16, 2021): 1233. http://dx.doi.org/10.3390/pr9071233.
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A performance assessment of wave power absorption characteristics of isolated and multiple wave energy converter (WEC) rotors was presented in this study for various wave-heading angles and wave frequencies. Numerical hydrodynamic analysis of the WEC was carried out using the three-dimensional linear boundary element method (BEM) and nonlinear computational fluid dynamics (CFD). Experimental results were used to validate the adopted numerical models. Influence with and without power take-off (PTO) was estimated on both isolated and multiple WEC rotors. Furthermore, to investigate the interaction effect among WECs, a q-factor was used. Incorporation of viscous and PTO damping into the linear BEM solution shows the maximum reduction focused around peak frequency but demonstrated an insignificant effect elsewhere. The q-factor showed both constructive and destructive interactions with the increase of the wave-heading angle and wave frequencies. Further investigation based on the prototype WEC rotor was carried, and calculated results of the linear BEM and the nonlinear CFD were compared. The pitch response and q-factor of the chosen wave frequencies demonstrated satisfactory consistency between the linear BEM and nonlinear CFD results, except for some wave frequencies. Estimated optimal time-averaged power using linear BEM show that the maximum extracted power close to the zero wave-heading angle around the resonance frequency decreases as the wave-heading angle increases. Overall, the linear BEM on the extracted power is overestimated compared with the nonlinear CFD results.
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Lee, Soo-Mok, Do-Hyeong Lim, Jong-Gug Bae, and Bo-Suk Yang. "Vibration Analysis of a Rotor considering Nonlinear Reaction of Hydrodynamic Bearing." International Journal of Fluid Machinery and Systems 2, no. 3 (September 1, 2009): 254–59. http://dx.doi.org/10.5293/ijfms.2009.2.3.254.
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Liu, Yao, Norimi Mizutani, and Yulin Zhao. "Nonlinear Hydrodynamic Analysis of Oscillating Wave Surge Converters under Regular Waves." International Journal of Offshore and Polar Engineering 31, no. 4 (December 1, 2021): 453–61. http://dx.doi.org/10.17736/ijope.2021.hc23.
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Amamou, Amira, and Mnaouar Chouchane. "Nonlinear stability analysis of long hydrodynamic journal bearings using numerical continuation." Mechanism and Machine Theory 72 (February 2014): 17–24. http://dx.doi.org/10.1016/j.mechmachtheory.2013.10.002.
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Feng, X., and W. Bai. "Hydrodynamic analysis of marine multibody systems by a nonlinear coupled model." Journal of Fluids and Structures 70 (April 2017): 72–101. http://dx.doi.org/10.1016/j.jfluidstructs.2017.01.016.
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Ye, Zhenni, Xiaoli Liu, Qinxi Dong, Enzhi Wang, and Huan Sun. "Hydro-Damage Properties of Red-Bed Mudstone Failures Induced by Nonlinear Seepage and Diffusion Effect." Water 14, no. 3 (January 25, 2022): 351. http://dx.doi.org/10.3390/w14030351.
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Nonlinear catastrophes caused by geological fluids are a fundamental issue in rock mechanics and the geoengineering hazard field. For the consideration of hydrodynamic force on red-bed mudstone softening damage, X-ray visualization tests on the fissure flow in mudstone block failure under hydrodynamic force was performed in this study based on block scale, and the physical phenomena of fissure seepage and nonlinear diffusion were further explored. A new method for evaluating the hydro-damage degrees of rocks using an X-ray image analysis was proposed, and the quantitative relation of diffusion coefficients of hydro-damage and seepage was established. The research results revealed that the hydrodynamic force promoted the fluid-filled fissure behavior in mudstone specimen failure. Furthermore, the seepage and diffusion phenomena of fluid in rocks during failures were indicated using X-ray imaging. A dual mechanical behavior was presented in the nonlinear seepage and abnormal diffusion of a red mudstone geological body under hydrodynamic conditions. The damaged degree of mudstone was aggravated by the effect of hydrodynamic force, and the initial seepage–diffusion coefficient with respect to lower hydro-damage was larger than the final seepage–diffusion coefficient with respect to higher hydro-damage of rocks with a decreasing nonlinear trend.
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Lyu, Dunyu, Chu Yu, Sha Ma, and Xiaowei Wang. "Nonlinear Seismic Response of a Hydraulic Tunnel Considering Fluid-Solid Coupling." Mathematical Problems in Engineering 2018 (November 5, 2018): 1–12. http://dx.doi.org/10.1155/2018/9608542.
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The seismic response of hydraulic tunnels is a complex nonlinear process. What makes the case even more interesting is that the large amount of water in hydraulic tunnels which is likely to induce considerable hydrodynamic pressure acted on tunnel structures during earthquakes. In this work, a full three-dimensional (3D) dynamic finite element model is adopted to conduct a comprehensive assessment of the seismic behaviors of a hydraulic tunnel system. In this analysis, the plastic-damage model is employed to reflect the nonlinear mechanical behaviors of the concrete lining, and a fluid-solid coupling method based on an explicit weighted residual approach is proposed to consider the effects of the hydrodynamic pressures on the seismic response of the hydraulic tunnel. The numerical results indicate that the hydrodynamic pressure contributes to a greater seismic response of the tunnel structure. When the hydrodynamic pressure is considered, the magnitudes of the maximum principal stresses are likely to increase by 50% and the displacement amplitudes are approximately 2 cm more than that of without hydrodynamic pressure. The hydrodynamic pressure exacerbates the damage degree of the tunnel structure, and the waist suffers the most severe damage.
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Li, Qiang, Shuo Zhang, Yujun Wang, Weiwei Xu, Zengli Wang, and Zhenbo Wang. "Dynamic characteristics of water-lubricated journal bearings." Mechanics & Industry 20, no. 4 (2019): 404. http://dx.doi.org/10.1051/meca/2019037.
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The increasing ecological awareness and stringent requirements for environmental protection have led to the development of water lubricated journal bearings. For the investigation of water-lubricated journal bearings, a new structured mesh movement algorithm for the CFD model is developed and based on this method, the nonlinear transient hydrodynamic force model is established. Then, with consideration of velocity perturbation, a method to determine dynamic coefficients and linear hydrodynamic forces is promoted. After validation of static equilibrium position and stiffness coefficients, a comparative linear and nonlinear hydrodynamic force analysis of multiple grooves water-lubricated journal bearings (MGWJBs) is conducted. The calculation results indicate that the structured mesh movement algorithm is suitable for the dynamic characteristics investigation of water-lubricated journal bearings. And the comparative study shows that there is a considerable difference between the linear and nonlinear hydrodynamic forces of MGWJBs. Further investigation should be carried to evaluate the dynamic responses of rotor supported by MGWJBs under difference force models.
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Kurths, J., A. Brandenburg, U. Feudel, and W. Jansen. "Chaos in Nonlinear Dynamo Models." Symposium - International Astronomical Union 157 (1993): 83–89. http://dx.doi.org/10.1017/s0074180900173917.
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Two nonlinear dynamos have been analyzed by numerical means: 3D-simulation of the magneto-hydrodynamic equations and qualitative analysis of a simplified low-dimensional mean field model. It turns out that both are capable of deterministic chaos in a certain parameter range. As the basic tool the calculation of Lyapunov exponents has been used.
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Hallak, Thiago S., C. Guedes Soares, Oscar Sainz, Sergio Hernández, and Alfonso Arévalo. "Hydrodynamic Analysis of the WIND-Bos Spar Floating Offshore Wind Turbine." Journal of Marine Science and Engineering 10, no. 12 (November 28, 2022): 1824. http://dx.doi.org/10.3390/jmse10121824.
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The WIND-bos spar Floating Offshore Wind Turbine is studied both experimentally and numerically. The experimental model of the moored WIND-bos platform is presented, and the different numerical models that have been developed to analyze the hydrodynamics of the platform are described. The results provide a detailed comparison of numerical and experimental motion responses of the floating structure in regular and irregular waves. The numerical study includes frequency domain results from spectral analysis, weakly nonlinear time-domain results from a validated in-house code, and coupled time-domain results from commercial software. The importance of damping calibration is put in evidence, whereas damping ratios are calculated iteratively in the coupled time-domain simulations, and nonlinear damping force is considered within the developed numerical scheme. The results compare well and also show that the novel concept has a good motion performance in general.
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Huang, Yifeng, and Paul D. Sclavounos. "Nonlinear Ship Motions." Journal of Ship Research 42, no. 02 (June 1, 1998): 120–30. http://dx.doi.org/10.5957/jsr.1998.42.2.120.
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A nonlinear numerical method has been developed to compute motion responses for a ship traveling in steep ambient waves. The method is based on an approximate theory and is an extension to a well-established linear time-domain numerical method. The nonlinear solution is found to be greatly improved over the classical linear and quasi-nonlinear solutions, in comparison to experimental measurements for conventional commercial ships. Through this study, it is also demonstrated that the free surface hydrodynamic nonlinearities are at least as important as, if not more than, the hydrostatic and Froude-Krylov nonlinearities. Stability, consistency and convergence for the nonlinear method are also addressed.
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Kokarakis, J. E., and M. M. Bernitsas. "Nonlinear Three-Dimensional Dynamic Analysis of Marine Risers." Journal of Energy Resources Technology 109, no. 3 (September 1, 1987): 105–11. http://dx.doi.org/10.1115/1.3231334.
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Marine risers are modeled as thin-walled, slender, extensible or inextensible, tubular beams subject to nonlinear three-dimensional hydrodynamic loads of interactive nature, torsion and distributed couples, inertia forces and varying axial tension. A finite element, time-incremental algorithm is developed which utilizes equilibrium and kinematic constraints to reduce the required computational time. Iterations are used within each increment to assure convergence of deformation, stiffness matrices and external loads. The algorithm is implemented numerically and the developed computer code is used in several numerical applications to show that a structurally linear model may not be accurate enough and may occasionally be nonconservative in predicting the dynamic riser response.
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Yoshida, Motoki, Takeshi Kinoshita, and Weiguang Bao. "Nonlinear Hydrodynamic Forces on an Accelerated Body in Waves." Journal of Offshore Mechanics and Arctic Engineering 127, no. 1 (February 1, 2005): 17–30. http://dx.doi.org/10.1115/1.1854699.
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Wave-drift added mass results from nonlinear interactions between waves and low-frequency oscillatory motions of a floating body, in the presence of incident waves. In previous works, wave-drift damping which is the component of wave-drift force in phase with the velocity of low-frequency oscillations was investigated mainly based on a quasi-steady analysis. However, investigations related to wave-drift added mass, the component in phase with acceleration, were very few. In this paper, wave-drift added mass is derived directly from a perturbation analysis with two small parameters and two time scales, using a Cartesian coordinate system that follows the low-frequency oscillations, dynamic oscillation model has been used. Especially, the method to solve higher-order potentials, which are necessary for evaluation of wave-drift added mass, is presented. Analytical solutions and calculated results of wave-drift added mass, and far field radiation conditions for each order of potentials are obtained. Also, wave-drift added mass of floating bodies has been systematically measured from a slowly forced oscillation test or a free decay test in waves. Experimental results are compared with calculated results. Then, for a supplement, the secular behavior that some velocity potentials show is discussed. Applying a multiple scale perturbation analysis to one of these problems, a nonsecular solution is obtained.
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Narayanan, S., and S. C. S. Yim. "Modeling and Identification of a Nonlinear SDOF Moored Structure, Part 1—Hydrodynamic Models and Algorithms." Journal of Offshore Mechanics and Arctic Engineering 126, no. 2 (May 1, 2004): 175–82. http://dx.doi.org/10.1115/1.1710875.
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The highly nonlinear responses of compliant ocean structures characterized by a large-geometry restoring force and coupled fluid-structure interaction excitation are of great interest to ocean and coastal engineers. Practical modeling, parameter identification, and incorporation of the inherent nonlinear dynamics in the design of these systems are essential and challenging. The general approach of a nonlinear system technique using very simple models has been presented in the literature by Bendat. In Part 1 of this two-part study, two specific nonlinear small-body hydrodynamic Morison type formulations: (A) with a relative-velocity (RV) model, and (B) with an independent flow-field (IFF) model, are formulated. Their associated nonlinear system-identification algorithms based on the reverse multiple-input/single-output (R-MI/SO) system-identification technique: (A.1) nonlinear-structure linearly damped, and (A.2) nonlinear-structure coupled hydrodynamically damped for the RV model, and (B.1) nonlinear-structure nonlinearly damped for the IFF model, are developed for a specific experimental submerged-sphere mooring system under ocean waves exhibiting such highly nonlinear response behaviors. In Part 2, using the measured input wave and output system response data, the algorithms derived based on the MI/SO linear analysis of the reverse dynamic systems are applied to identify the properties of the highly nonlinear system. Practical issues on the application of the R-MI/SO technique based on limited available experimental data are addressed.
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Hicks, J. D., A. W. Troesch, and C. Jiang. "Simulation and Nonlinear Dynamics Analysis of Planing Hulls." Journal of Offshore Mechanics and Arctic Engineering 117, no. 1 (February 1, 1995): 38–45. http://dx.doi.org/10.1115/1.2826989.
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The high speeds, small trim angles, and shallow drafts of planing hulls produce large changes in vessel wetted surface which, in turn, lead to significant hydrodynamic and dynamic nonlinearities. Due to the complex nonlinearities of this type of craft, naval architects and planing boat designers tend to rely upon experimental tests or simulation for guidance. In order for simulation to be an effective design tool, a fundamental understanding of the system’s dynamic characteristics is required. This paper describes a developing methodology by which the necessary insight may be obtained. A demonstration of the combined use of modern methods of dynamical system analysis with simulation is given in the evaluation of the vertical motions of a typical planing hull. Extending the work of Troesch and Hicks (1992) and Troesch and Falzarano (1993), the complete nonlinear hydrodynamic force and moment equations of Zarnick (1978) are expanded in a multi-variable Taylor series. As a result, the nonlinear integro-differential equations of motion are replaced by a set of highly coupled, ordinary differential equations with constant coefficients, valid through third order. Closed-form, analytic expressions are available for the coefficients (Hicks, 1993). Numerical examples for all first-order and some second-order terms are presented. Once completely determined, the coefficient matrices will serve as input to path following or continuation methods (e.g., Seydel, 1988) where heave and pitch magnification curves can be generated, allowing the entire system response to be viewed. The branching behavior of the solutions resulting from a variation of the center of gravity is examined in detail. These studies of the second-order accurate model show the potential of the method to identify areas of critical dynamic response, which in turn can be verified and explored further through the use of the simulator.
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MARIAPPAN, SATHESH, and R. I. SUJITH. "Modelling nonlinear thermoacoustic instability in an electrically heated Rijke tube." Journal of Fluid Mechanics 680 (May 25, 2011): 511–33. http://dx.doi.org/10.1017/jfm.2011.176.
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An analysis of thermoacoustic instability is performed for a horizontal Rijke tube with an electrical resistance heater as the heat source. The governing equations for this fluid flow become stiff and are difficult to solve by the computational fluid dynamics (CFD) technique, as the Mach number of the steady flow and the thickness of the heat source (compared to the acoustic wavelength) are small. Therefore, an asymptotic analysis is performed in the limit of small Mach number and compact heat source to eliminate the above stiffness problem. The unknown variables are expanded in powers of Mach number. Two systems of governing equations are obtained: one for the acoustic field and the other for the unsteady flow field in the hydrodynamic zone around the heater. In this analysis, the coupling between the acoustic field and the unsteady heat release rate from the heater appears from the asymptotic analysis. Furthermore, a non-trivial additional term, referred to as the global-acceleration term, appears in the momentum equation of the hydrodynamic zone, which has serious consequences for the stability of the system. This term can be interpreted as a pressure gradient applied from the acoustic onto the hydrodynamic zone. The asymptotic stability of the system with the variation of system parameters is presented using the bifurcation diagram. Numerical simulations are performed using the Galerkin technique for the acoustic zone and CFD techniques for the hydrodynamic zone. The results confirm the importance of the global-acceleration term. Bifurcation diagrams obtained from the simulations with and without the above term are different. Acoustic streaming is shown to occur during the limit cycle and its effect on the unsteady heat release rate is discussed.
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Del Vecchio Del Vecchio, Giuseppe, and Benjamin Doyon. "The hydrodynamic theory of dynamical correlation functions in the XX chain." Journal of Statistical Mechanics: Theory and Experiment 2022, no. 5 (May 1, 2022): 053102. http://dx.doi.org/10.1088/1742-5468/ac6667.
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Abstract By the hydrodynamic linear response theory, dynamical correlation functions decay as power laws along certain velocities, determined by the flux Jacobian. Such correlations are obtained by hydrodynamic projections, and physically, they are due to propagating ‘sound waves’ or generalisation thereof, transporting conserved quantities between the observables. However, some observables do not emit sound waves, such as order parameters associated to symmetry breaking. In these cases correlation functions decay exponentially everywhere, a behaviour not captured by the hydrodynamic linear response theory. Focussing on spin–spin correlation functions in the XX quantum chain, we first review how hydrodynamic linear response works, emphasising that the necessary fluid cell averaging washes out oscillatory effects. We then show how, beyond linear response, Euler hydrodynamics can still predict the exponential decay of correlation functions of order parameters. This is done by accounting for the large-scale fluctuations of domain walls, via the recently developed ballistic fluctuation theory. We use the framework of generalised hydrodynamics, which is particularly simple in this model due to its free fermion description. In particular, this reproduces, by elementary calculations, the exponential decay in the celebrated formulae by Its et al (1993) and by Jie (1998), which were originally obtained by intricate Fredholm determinant analysis; and gives a new formula in a parameter domain where no result was obtained before. We confirm the results by numerical simulations.
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Zelle, Dennis, Ernst Dalhoff, and Anthony W. Gummer. "Time-domain analysis of distortion-product otoacoustic emissions using a hydrodynamic cochlea model." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 453–56. http://dx.doi.org/10.1515/cdbme-2017-0095.
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AbstractAs a by-product of nonlinear amplification in the cochlea, the inner ear emits sound waves in response to two tones with different frequencies. These sound waves are measurable in the ear canal as distortion-product otoacoustic emissions (DPOAEs). DPOAEs putatively consist of two components emerging at different locations in the cochlea. Wave interference between the two components limits the accuracy of DPOAEs as a noninvasive measure of cochlear function. Using short stimulus pulses instead of continuous stimuli, the two DPOAE components can be separated in the time domain due to their different latencies. The present work utilizes a nonlinear hydrodynamic cochlea model to simulate short-pulse DPOAEs in the time domain. When adding irregularities to the mechanical parameters of the model, the simulated DPOAE signals show two distinguishable components and long-lasting beat tones, similar to band-pass filtered experimental data from normal-hearing human subjects. The model results suggest that the beat tones can occur solely due to interference of the coherent-reflection component with the fading nonlinear-distortion component.
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Delprete, Cristiana, Abbas Razavykia, and Paolo Baldissera. "Detailed analysis of piston secondary motion and tribological performance." International Journal of Engine Research 21, no. 9 (February 28, 2019): 1647–61. http://dx.doi.org/10.1177/1468087419833883.
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This article presents a detailed analytical model to evaluate piston skirt tribology under hydrodynamic lubrication. The contribution of the piston ring pack lubrication has been taken into account to study piston secondary motion and tribological performance. A system of nonlinear equations comprising Reynolds equation and force equilibrium is solved to calculate piston ring pack friction force and its moment about wrist pin axis. Instantaneous minimum oil film thickness at piston ring/liner interface has been estimated considering different boundary conditions: full Sommerfeld, oil separation, and Reynolds cavitation and reformation. The ring pack model has capability to be used for a wide range of ring face profiles under boundary and hydrodynamic lubrication. Piston secondary motion is evaluated using lubrication theory and equilibrium of forces and moments, to examine the effect of wrist pin location, piston skirt/liner clearance, and oil rheology. Numerical method and finite difference scheme have been used to define piston eccentricity and hydrodynamic pressure acting over the skirt.
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Clarisse, J. M., J. L. Pfister, S. Gauthier, and C. Boudesocque-Dubois. "A hydrodynamic analysis of self-similar radiative ablation flows." Journal of Fluid Mechanics 848 (June 5, 2018): 219–55. http://dx.doi.org/10.1017/jfm.2018.343.
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Self-similar solutions to the compressible Euler equations with nonlinear conduction are considered as particular instances of unsteady radiative deflagration – or ‘ablation’ – waves with the goal of characterizing the actual hydrodynamic properties that such flows may present. The chosen family of solutions, corresponding to the ablation of an initially quiescent perfectly cold and homogeneous semi-infinite slab of inviscid compressible gas under the action of increasing external pressures and radiation fluxes, is well suited to the description of the early ablation of a target by gas-filled cavity X-rays in experiments of high energy density physics. These solutions are presently computed by means of a highly accurate numerical method for the radiative conduction model of a fully ionized plasma under the approximation of a non-isothermal leading shock wave. The resulting set of solutions is unique for its high fidelity description of the flows down to their finest scales and its extensive exploration of external pressure and radiative flux ranges. Two different dimensionless formulations of the equations of motion are put forth, yielding two classifications of these solutions which are used for carrying out a quantitative hydrodynamic analysis of the corresponding flows. Based on the main flow characteristic lengths and on standard characteristic numbers (Mach, Péclet, stratification and Froude numbers), this analysis points out the compressibility and inhomogeneity of the present ablative waves. This compressibility is further analysed to be too high, whether in terms of flow speed or stratification, for the low Mach number approximation, often used in hydrodynamic stability analyses of ablation fronts in inertial confinement fusion (ICF), to be relevant for describing these waves, and more specifically those with fast expansions which are of interest in ICF. Temperature stratification is also shown to induce, through the nonlinear conductivity, supersonic upstream propagation of heat-flux waves, besides a modified propagation of quasi-isothermal acoustic waves, in the flow conduction regions. This description significantly departs from the commonly admitted depiction of a quasi-isothermal conduction region where wave propagation is exclusively ascribed to isothermal acoustics and temperature fluctuations are only diffused.
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Zhou, Yu, Dezhi Ning, Dongfang Liang, and Shuqun Cai. "Nonlinear hydrodynamic analysis of an offshore oscillating water column wave energy converter." Renewable and Sustainable Energy Reviews 145 (July 2021): 111086. http://dx.doi.org/10.1016/j.rser.2021.111086.
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Chen, Bang-Fuh. "3D Nonlinear Hydrodynamic Analysis of Vertical Cylinder during Earthquakes. I: Rigid Motion." Journal of Engineering Mechanics 123, no. 5 (May 1997): 458–65. http://dx.doi.org/10.1061/(asce)0733-9399(1997)123:5(458).
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Matsuura, Joa˜o Paulo J., Kazuo Nishimoto, Michael M. Bernitsas, and Luis O. Garza-Rios. "Comparative Assessment of Hydrodynamic Models in Slow-Motion Mooring Dynamics." Journal of Offshore Mechanics and Arctic Engineering 122, no. 2 (September 10, 1999): 109–17. http://dx.doi.org/10.1115/1.533732.
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The slow-motion dynamics of a turret mooring system is analyzed and compared for four of the most commonly used ship hydrodynamic maneuvering models. Each of those utilizes a different approach to model and then to calculate or measure the hydrodynamic forces and moment acting on the vessel. The four hydrodynamic maneuvering models are studied first by a physics-based analysis of each model and then by numerically comparing their prediction of equilibria, nonlinear stability analysis, bifurcation sequences, and morphogeneses of turret mooring systems. Catastrophe sets are constructed in two-dimensional parametric design spaces to determine the qualitative behavior of the system, and nonlinear time simulations are used to assess its quantitative properties. Static bifurcations of the principal equilibrium are compared to determine the nature of alternate equilibria. A turret-moored tanker is modeled with anchored catenaries, including nonlinear drag. External excitation is time independent, and for the numerical applications it is limited to steady current. Of the four models used, the Abkowitz and Takashina models show similar qualitative dynamics. The Obokata and Short-Wing models are also qualitatively similar, but very different from the first group. Limited sensitivity analysis pinpoints the source of discrepancy between the two schools of thought. [S0892-7219(00)01401-1]
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WOOD-VASEY, W. M., K. S. BUDIL, B. A. REMINGTON, S. G. GLENDINNING, A. M. RUBENCHIK, M. BERNING, J. O. KANE, and J. T. LARSEN. "Computational modeling of classical and ablative Rayleigh–Taylor instabilities." Laser and Particle Beams 18, no. 4 (October 2000): 583–93. http://dx.doi.org/10.1017/s0263034600184022.
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Modeling plus simulations using the one-dimensional Lagrangian radiation-hydrodynamics code HYADES are compared with data from classical and ablative Rayleigh–Taylor experiments conducted on the Nova laser. Comparisons between the experiments and modeling for both the gross hydrodynamic motion and the perturbation evolution are made and show good agreement. A third order perturbation analysis is applied to demonstrate the onset of nonlinearity. A simple, physically intuitive saturation model is used to describe the growth further into the nonlinear regime. Finally, we present the first comparison of the Betti ablation front theory with indirect-drive RT data and obtain good agreement.
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He, Yu-Chu, Geng Zhang, and Dong Chen. "Effect of density integration on the stability of a new lattice hydrodynamic model." International Journal of Modern Physics B 33, no. 09 (April 10, 2019): 1950071. http://dx.doi.org/10.1142/s0217979219500711.
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A novel traffic lattice hydrodynamic model considering the effect of density integration is proposed and analyzed in the paper. Via linear stability theory, linear stability condition of the new model is derived, which reveals an improvement of traffic stability by considering the integration of continuous historical density information. Moreover, the nonlinear properties of the extended model are revealed through nonlinear analysis. The propagating backwards kink–antikink waves are generated by deriving the mKdV equation near the critical point and verified by numerical simulation. All the results show that the density integration effect can suppress traffic congestion efficiently in traffic lattice hydrodynamic modeling.
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Khayat, Roger E., and Byung Chan Eu. "Generalized hydrodynamics and linear stability analysis of cylindrical Couette flow of a dilute Lennard–Jones fluid." Canadian Journal of Physics 71, no. 11-12 (November 1, 1993): 518–36. http://dx.doi.org/10.1139/p93-081.
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Linear stability analysis is carried out for cylindrical Couette flow of a Lennard–Jones fluid in the density range from the dense liquid to the dilute gas regime. Generalized hydrodynamic equations are used to calculate marginal stability curves and compare them with those obtained by using the Navier–Stokes–Fourier equations for compressible fluids and also for incompressible fluids. In the low Reynolds or Mach number regime, if the Knudsen number is sufficiently low, the marginal stability curves calculated by the generalized hydrodynamic theory coincide, within numerical errors, with those based on the Navier–Stokes theory. But there are considerable deviations between them in the regimes beyond those mentioned earlier, since nonlinear effects manifest themselves in the laminar mean flow through the nonlinear dissipation term and normal stresses. There are three marginal stability curves obtained in contrast to the Navier–Stokes theory, which yields only two. The previously observed phase-transition-like behavior in fluid variables and the slip phenomenon are found to occur beyond the hydrodynamic stability point. The disturbance entropy production associated with the Taylor–Couette vortices is calculated to first order in disturbances in flow variables and is found to decrease as the number of vortices increases and thereby the dynamic structure is progressively more organized.
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Sun, Wei, Hui Long Ren, and Hui Li. "Study on the Treatment of Nonlinear Roll Damping in Hydrodynamic Calculation and Structural Analysis." Applied Mechanics and Materials 687-691 (November 2014): 423–27. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.423.
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In order to insure the consistent wave loads in hydrodynamic calculation and structural analysis, the treatment of nonlinear roll damping in roll motion, wave torsional moment and structural analysis are studied. The nonlinear roll damping moment is applied to the structural model by means of the equivalent nodal forces. Taking a supply ship and a FPSO as example, the calculation results show that the problem of torsional moment distribution divergent on the bow and the unbalanced structural model is improved greatly, which would be helpful to provide the reliable basis to design the structures.
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Liu, Fuhao, Hanjun Jiang, Liang Zhang, and Li Chen. "Analysis of vibration characteristic for helical gear under hydrodynamic conditions." Advances in Mechanical Engineering 9, no. 1 (January 2017): 168781401668796. http://dx.doi.org/10.1177/1687814016687962.
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Based on the elasto-hydrodynamic lubrication theory, a 2-degree-of-freedom nonlinear dynamic model of helical gears with double-sided film is proposed, in which the minimum film thickness behaves as a function of load parameters, lubricant parameters, and the geometry of the contact. Then, the comparison of the hysteresis loops in different gear models shows the soundness of the presented model. Using numerical method, the time evolution of lubricant normal force, minimum film thickness, and lubricant stiffness is obtained in order to demonstrate the influence of the driving torque and pinion’s velocity. The results obtained in this article can contribute to the root cause for the gear vibration and show that the hydrodynamic flank friction has almost no influence on the gear system.
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Zhao, Yong. "Finite Element Modeling and Analysis of Nonlinear Impact and Frictional Motion Responses Including Fluid—Structure Coupling Effects." Shock and Vibration 4, no. 5-6 (1997): 311–25. http://dx.doi.org/10.1155/1997/496945.
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A nonlinear three dimensional (3D) single rack model and a nonlinear 3D whole pool multi-rack model are developed for the spent fuel storage racks of a nuclear power plant (NPP) to determine impacts and frictional motion responses when subjected to 3D excitations from the supporting building floor. The submerged free standing rack system and surrounding water are coupled due to hydrodynamic fluid-structure interaction (FSI) using potential theory. The models developed have features that allow consideration of geometric and material nonlinearities including (1) the impacts of fuel assemblies to rack cells, a rack to adjacent racks or pool walls, and rack support legs to the pool floor; (2) the hydrodynamic coupling of fuel assemblies with their storing racks, and of a rack with adjacent racks, pool walls, and the pool floor; and (3) the dynamic motion behavior of rocking, twisting, and frictional sliding of rack modules. Using these models 3D nonlinear time history dynamic analyses are performed per the U.S. Nuclear Regulatory Commission (USNRC) criteria. Since few such modeling, analyses, and results using both the 3D single and whole pool multiple rack models are available in the literature, this paper emphasizes description of modeling and analysis techniques using the SOLVIA general purpose nonlinear finite element code. Typical response results with different Coulomb friction coefficients are presented and discussed.
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Chung, J. S. "Stability-Based Design of Two-Point Mooring Systems With Hydrodynamic Memory." Journal of Offshore Mechanics and Arctic Engineering 119, no. 1 (February 1, 1997): 61–69. http://dx.doi.org/10.1115/1.2829047.
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A systematic method of determining the design parameter values of two-point mooring (TPM) systems is presented. The conclusions of nonlinear stability analysis of horizontal plane slow motion dynamics of TPM systems with hydrodynamic memory are used to guide selection of the design variables. Specifically, within the stable regions of bifurcation diagram, a set of parameter values is chosen systematically to examine the corresponding TPM system. Then, each TPM system is simulated and the results are evaluated in terms of given criteria such as tension level of the mooring line or offset of the moored vessel. The hydrodynamic memory effect due to the oscillatory motions of moored vessel is included in the formulation. The memory effect influences the stability properties of TPM systems and alters the design chart/bifurcation diagram and particularly the static loss and dynamic loss of stability. The significance of hydrodynamic memory on several TPM systems is illustrated by comparing the statistics of the simulations. The design approach implemented in this work shows that nonlinear stability theory can be used effectively in the actual design process of mooring systems to reduce dramatically the number of simulations required. It is also shown that the often inconclusive nonlinear time simulations can be guided by theoretical nonlinear stability analysis of system dynamics to produce improved design values of system parameters of TPM systems.
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Li, Lixiang, Hongxia Ge, and Rongjun Cheng. "Analysis of the predictive effect and feedback control in an extended lattice hydrodynamic model." Engineering Computations 37, no. 5 (December 16, 2019): 1645–61. http://dx.doi.org/10.1108/ec-07-2019-0297.
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Purpose This paper aims to put forward an extended lattice hydrodynamic model, explore its effects on alleviating traffic congestion and provide theoretical basis for traffic management departments and traffic engineering implementation departments. Design/methodology/approach The control method is applied to study the stability of the new model. Through nonlinear analysis, the mKdV equation representing kink-antikink soliton is acquired. Findings The predictive effect and the control signal can enhance the traffic flow stability and reduce the energy consumption. Originality/value The predictive effect and feedback control are first considered in lattice hydrodynamic model simultaneously. Numerical simulations demonstrate that these two factors can enhance the traffic flow stability.
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Kihara, Hajime, Shigeru Naito, and Makoto Sueyoshi. "Numerical Analysis of the Influence of Above-Water Bow Form on Added Resistance Using Nonlinear Slender Body Theory." Journal of Ship Research 49, no. 03 (September 1, 2005): 191–206. http://dx.doi.org/10.5957/jsr.2005.49.3.191.
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A nonlinear numerical method is presented for the prediction of the hydrodynamic forces that act on an oscillating ship with a forward speed in head waves. A "parabolic" approximation of equations called "2.5D" or "2D+T" theory was used in a three-dimensional ship wave problem, and the computation was carried out in the time domain. The nonlinear properties associated with the hydrostatic, hydrodynamic, and Froude-Krylov forces were taken into account in the framework of the slender body theory. This work is an extension of the previous work of Kihara and Naito (1998). The application of this approach to the unsteady wave-making problem of a ship with a real hull form is described. The focus is on the influence of the above-water hull form on the horizontal mean wave force. Comparison with experimental results demonstrates that the method is valid in predicting added resistance. Prediction of added resistance for blunt ships is also shown by example.