Academic literature on the topic 'Coupling between hydrodynamic modes'
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Journal articles on the topic "Coupling between hydrodynamic modes"
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JIA, LAI-BING, FANG LI, XIE-ZHEN YIN, and XIE-YUAN YIN. "Coupling modes between two flapping filaments." Journal of Fluid Mechanics 581 (May 22, 2007): 199–220. http://dx.doi.org/10.1017/s0022112007005563.
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The flapping coupling between two filaments is studied theoretically and experimentally in this paper. A temporal linear instability analysis is carried out based on a simplified hydrodynamic model. The dispersion relationship between the eigen-frequency ω and wavenumber k is expressed by a quartic equation. Two special cases of flapping coupling, i.e. two identical filaments having the same length and two filaments having different lengths, are studied in detail. In the case of two identical filaments, the theoretical analysis predicts four coupling modes, i.e. the stretched-straight mode, the antisymmetrical in-phase mode, the symmetrical out-of-phase mode and the indefinite mode. The theory also predicts the existence of an eigenfrequency jump during transition between the in-phase and out-of-phase modes, which has been observed in previous experiments and numerical simulations. In the case of two filaments having different lengths, four modes similar to those in the former case are identified theoretically. The distribution of coupling modes for both the cases is shown in two planes. One is a dimensionless plane of S vs. U, where S is the density ratio of solid filament to fluid and U2 is the ratio of fluid kinetic energy to solid elastic potential energy. The other is a dimensional plane of the half-distance (h) between two filaments vs. the filament length (L). Relevant experiments are carried out in a soap-film tunnel and the stable and unstable modes are observed. Theory and experiment are compared in detail. It should be noted that the model used in our analysis is a very simplified one that can provide intuitional analytical results of the coupling modes as well as their qualitative distributions. The factors neglected in our model, such as vortex shedding, viscous and nonlinear effects, do not allow the model to predict results precisely consistent with the experiments. Moreover, the Strouhal numbers of the flapping filaments are found to be generally around a fixed value in the experiments for both cases, implying that the filaments try to maintain a lower potential energy state.
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Puhl, A., V. Altares, and G. Nicolis. "Imperfect turbulent mixing in chemical reactors: Coupling between chemical and hydrodynamic modes." Physical Review A 37, no. 8 (April 1, 1988): 3039–45. http://dx.doi.org/10.1103/physreva.37.3039.
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Guo, Hanliang, Yi Man, Kirsty Y. Wan, and Eva Kanso. "Intracellular coupling modulates biflagellar synchrony." Journal of The Royal Society Interface 18, no. 174 (January 2021): 20200660. http://dx.doi.org/10.1098/rsif.2020.0660.
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Beating flagella exhibit a variety of synchronization modes. This synchrony has long been attributed to hydrodynamic coupling between the flagella. However, recent work with flagellated algae indicates that a mechanism internal to the cell, through the contractile fibres connecting the flagella basal bodies, must be at play to actively modulate flagellar synchrony. Exactly how basal coupling mediates flagellar coordination remains unclear. Here, we examine the role of basal coupling in the synchronization of the model biflagellate Chlamydomonas reinhardtii using a series of mathematical models of decreasing levels of complexity. We report that basal coupling is sufficient to achieve inphase, antiphase and bistable synchrony, even in the absence of hydrodynamic coupling and flagellar compliance. These modes can be reached by modulating the activity level of the individual flagella or the strength of the basal coupling. We observe a slip mode when allowing for differential flagellar activity, just as in experiments with live cells. We introduce a dimensionless ratio of flagellar activity to basal coupling that is predictive of the mode of synchrony. This ratio allows us to query biological parameters which are not yet directly measurable experimentally. Our work shows a concrete route for cells to actively control the synchronization of their flagella.
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Balescu, R., H. Bessenrodt, P. K. Shukla, and K. H. Spatschek. "Instability and saturation of drift-convective modes in an inhomogeneous plasma." Journal of Plasma Physics 37, no. 2 (April 1987): 163–73. http://dx.doi.org/10.1017/s0022377800012083.
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It is found that the inclusion of the electron inertia effect (parallel to an external magnetic field) can provide a linear coupling between the electrostatic drift and the convective modes in a non-uniform plasma. This coupling leads to new branches of rapidly growing modes, which are calculated in the kinetic as well as in the hydrodynamic regimes. To study the saturation of the linear unstable modes, we account for the mode coupling and derive a set of model nonlinear fluid equations. A perturbation technique is employed to obtain a nonlinear evolution equation. In the steady state, the latter yields the saturated electric potential. It is argued that the enhanced low-frequency fluctuations can cause anomalous particle transport in a magnetoplasma.
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Híjar, Humberto, Rene Halver, and Godehard Sutmann. "Spontaneous Fluctuations in Mesoscopic Simulations of Nematic Liquid Crystals." Fluctuation and Noise Letters 18, no. 03 (July 16, 2019): 1950011. http://dx.doi.org/10.1142/s0219477519500111.
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We analyzed hydrodynamic fluctuations in nematic liquid crystals simulated by Multi-particle Collision Dynamics. Velocity effects on orientation were incorporated by allowing mesoscopic velocity gradients to exert torques on nematic particles. Backflow was included through an explicit application of angular momentum conservation during the collision events. We measured the spectra of hydrodynamic fluctuations and compared them with those derived from a linearized hydrodynamic scheme. Numerical results were found to reproduce the expected coupling between hydrodynamic modes, thus showing that the implementation simulates proper nematodynamic effects at the mesoscopic level.
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Hoch, Jannis M., Arjen V. Haag, Arthur van Dam, Hessel C. Winsemius, Ludovicus P. H. van Beek, and Marc F. P. Bierkens. "Assessing the impact of hydrodynamics on large-scale flood wave propagation – a case study for the Amazon Basin." Hydrology and Earth System Sciences 21, no. 1 (January 9, 2017): 117–32. http://dx.doi.org/10.5194/hess-21-117-2017.
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Abstract. Large-scale flood events often show spatial correlation in neighbouring basins, and thus can affect adjacent basins simultaneously, as well as result in superposition of different flood peaks. Such flood events therefore need to be addressed with large-scale modelling approaches to capture these processes. Many approaches currently in place are based on either a hydrologic or a hydrodynamic model. However, the resulting lack of interaction between hydrology and hydrodynamics, for instance, by implementing groundwater infiltration on inundated floodplains, can hamper modelled inundation and discharge results where such interactions are important. In this study, the global hydrologic model PCR-GLOBWB at 30 arcmin spatial resolution was one-directionally and spatially coupled with the hydrodynamic model Delft 3D Flexible Mesh (FM) for the Amazon River basin at a grid-by-grid basis and at a daily time step. The use of a flexible unstructured mesh allows for fine-scale representation of channels and floodplains, while preserving a coarser spatial resolution for less flood-prone areas, thus not unnecessarily increasing computational costs. In addition, we assessed the difference between a 1-D channel/2-D floodplain and a 2-D schematization in Delft 3D FM. Validating modelled discharge results shows that coupling PCR-GLOBWB to a hydrodynamic routing scheme generally increases model performance compared to using a hydrodynamic or hydrologic model only for all validation parameters applied. Closer examination shows that the 1-D/2-D schematization outperforms 2-D for r2 and root mean square error (RMSE) whilst having a lower Kling–Gupta efficiency (KGE). We also found that spatial coupling has the significant advantage of a better representation of inundation at smaller streams throughout the model domain. A validation of simulated inundation extent revealed that only those set-ups incorporating 1-D channels are capable of representing inundations for reaches below the spatial resolution of the 2-D mesh. Implementing 1-D channels is therefore particularly of advantage for large-scale inundation models, as they are often built upon remotely sensed surface elevation data which often enclose a strong vertical bias, hampering downstream connectivity. Since only a one-directional coupling approach was tested, and therefore important feedback processes are not incorporated, simulated discharge and inundation extent for both coupled set-ups is generally overpredicted. Hence, it will be the subsequent step to extend it to a two-directional coupling scheme to obtain a closed feedback loop between hydrologic and hydrodynamic processes. The current findings demonstrating the potential of one-directionally and spatially coupled models to obtain improved discharge estimates form an important step towards a large-scale inundation model with a full dynamic coupling between hydrology and hydrodynamics.
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Ciracì, Cristian, Radoslaw Jurga, Muhammad Khalid, and Fabio Della Sala. "Plasmonic quantum effects on single-emitter strong coupling." Nanophotonics 8, no. 10 (August 14, 2019): 1821–33. http://dx.doi.org/10.1515/nanoph-2019-0199.
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AbstractCoupling between electromagnetic cavity fields and fluorescent molecules or quantum emitters can be strongly enhanced by reducing the cavity mode volume. Plasmonic structures allow light confinement down to volumes that are only a few cubic nanometers. At such length scales, nonlocal and quantum tunneling effects are expected to influence the emitter interaction with the surface plasmon modes, which unavoidably requires going beyond classical models to accurately describe the electron response at the metal surface. In this context, the quantum hydrodynamic theory (QHT) has emerged as an efficient tool to probe nonlocal and quantum effects in metallic nanostructures. Here, we apply state-of-the-art QHT to investigate the quantum effects on strong coupling of a dipole emitter placed at nanometer distances from metallic particles. A comparison with conventional local response approximation (LRA) and Thomas-Fermi hydrodynamic theory results shows the importance of quantum effects on the plasmon-emitter coupling. The QHT predicts qualitative deviation from LRA in the weak coupling regime that leads to quantitative differences in the strong coupling regime. In nano-gap systems, the inclusion of quantum broadening leads to the existence of an optimal gap size for Rabi splitting that minimizes the requirements on the emitter oscillator strength.
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Tran, N., N. Y. Sergiienko, B. S. Cazzolato, M. H. Ghayesh, and M. Arjomandi. "Design considerations for a three-tethered point absorber wave energy converter with nonlinear coupling between hydrodynamic modes." Ocean Engineering 254 (June 2022): 111351. http://dx.doi.org/10.1016/j.oceaneng.2022.111351.
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Zhang, Qinghe, Chao Ji, Jinfeng Zhang, and Yuefeng Wu. "DEVELOPMENT OF A THREE DIMENSIONAL NUMERICAL MODEL OF SEDIMENT TRANSPORT AND MORPHOLOGICAL EVOLUTION ON SANDY BEACH." Coastal Engineering Proceedings, no. 36v (December 28, 2020): 41. http://dx.doi.org/10.9753/icce.v36v.sediment.41.
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In recent years, sandy coasts are suffering from erosion. It is of great importance to evaluate the state of coasts and assure the achievement of coastal protection measures. Therefore, a three-dimensional numerical model of sandy beach response was developed based on unstructured grids and with capability of describing nearshore hydrodynamics and sediment transports. A three-dimensional hydrodynamic model was first developed based on a coupled wave-current model system that included the Simulating Waves Nearshore (SWAN) wave model and the Finite Volume Community Ocean Model (FVCOM) circulation model. Information exchange between the two models used Model-Coupling Toolkit (MCT) software following Chen et al. (2018). The new three-dimensional radiation stress including the bottom slope effects was employed (Ji et al. 2017). Based on the hydrodynamic model, a numerical model of sediment transport and morphological evolution on sandy beach was developed.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/BVVn1kfViH0
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Fahr, H. J. "The charge-exchange induced coupling between plasma-gas counterflows in the heliosheath." Annales Geophysicae 21, no. 6 (June 30, 2003): 1289–94. http://dx.doi.org/10.5194/angeo-21-1289-2003.
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Abstract. Many hydrodynamic models have been presented which give similar views of the interaction of the solar wind plasma bubble with the counterstreaming partially ionized interstellar medium. In the more recent of these models it is taken into account that the solar and interstellar hydrodynamic flows of neutral atoms and protons are coupled by mass-, momentum-, and energy-exchange terms due to charge exchange processes. We shall reinvestigate the theoretical basis of this coupling here by use of a simplified description of the heliospheric interface and describe the main physics of the H-atom penetration through the more or less standing well-known plasma wall ahead of the heliopause. Thereby we can show that the type of charge exchange coupling terms used in up-to-now hydrodynamic treatments unavoidably leads to an O-type critical point at the sonic point of the H-atom flow, thus not allowing for a continuation of the integration of the hydrodynamic set of differential equations. The remedy for this problem is given by a more accurate formulation of the momentum exchange term for quasi-and sub-sonic H-atom flows. With a refined momentum exchange term derived from basic kinetic Boltzmann principles, we instead arrive at a characteristic equation with an X-type critical point, allowing for a continuous solution from supersonic to subsonic flow conditions. This necessitates that the often treated problem of the propagation of inter-stellar H-atoms through the heliosheath has to be solved using these newly derived, differently effective plasma – gas friction forces. Substantially different results are to be expected from this context for the filtration efficiency of the heliospheric interface.Key words. Interplanetary physics (heliopause and solar wind termination; interstellar gas) – Ionosphere (plasma temperature and density)
Dissertations / Theses on the topic "Coupling between hydrodynamic modes"
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Truitt, Patrick A. "Measurement of coupling between the electron gas and nanomechanical modes." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7738.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Lopez, Hector Matias. "Influence of the coupling between flow and bacteria on the fluid rheology and on bacterial transport." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112168.
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Le transport des micro-organismes, comme par exemple les bactéries, par un fluide se retrouve au centre de thématiques de recherche dans des domaines aussi variés que de la biologie, l’écologie, l’ingénierie et la médecine.Ce manuscrit résume mon étude expérimentale du couplage entre le mouvement microscopique de la nage des bactéries et le mouvement advectif de l’écoulement.La première partie du manuscrit porte sur la rhéologie des suspensions d’E. coli sous faible taux de cisaillement. Pour cette condition, j’ai montré que les perturbations hydrodynamiques induites par la nage réduisent fortement la viscosité. Cet effet peut-être si important pour qu’il soit suffisant pour compenser entièrement la perte visqueuse due au cisaillement.La seconde partie traite des expériences d’écoulement réalisées dans un canal capillaire. Pour cette géométrie, j’ai examiné le couplage pour des écoulements caractérisés par un plus fort taux de cisaillement. Le suivi des trajectoires et le dénombrement des bactéries m’ont permis de mettre en évidence l’existence d’une composante de vitesse normal à la direction de l’écoulement. Cette dernière montre que les bactéries suivent des trajectoires hélicoïdales qui s’enroulent autour du centre du capillaire d’une façon antihoraires. Cette nouvelle composante est corrélée à la migration préférentielle des bactéries dans une couche de localisation proche de la paroi du canal.Les couplages rhéotactiques bactéries/fluide que j’ai étudiés doivent avoir des conséquences potentielles sur le transport en géométries plus complexes qui mériteraient une étude particulièreThe question of transfer and spreading of living microorganisms, such as motile bacteria, is of interest in biology and ecology, but also in engineering and medicine.The way in which the background flow affects the behavior of these bacteria and how it impacts the bacterial transport through complex systems and on the macroscopic properties of the fluid remains unclear and little studied.In this thesis, I present an experimental investigation of the coupling between the local bacteria-driven motion and the fluid advection.In a first part, I investigate the rheological response of E. coli suspensions when subjected to weak flows (low shear rates). I show that, in particular conditions, the microscopic perturbations caused by the bacteria highly impact on the macroscopic viscosity of the suspension, leading to a striking viscosity decrease and eventually overcoming the dissipative effects due to viscous loss. I also identify the relevant time scales defining this viscosity decrease.In a second part, I perform experiments in a capillary channel and analyze the coupling for stronger flows (higher shear rates), at which bacteria were found not to impact on the macroscopic viscosity. Instead, by analyzing the bacterial trajectories under flow, I evidence a breakage of the symmetry of this trajectories which, characterized by a preferential migration, causes the localization of the bacteria in a layer that extends over a significant distance from the surface, and thus potentially influencing the bacterial transport in complex systems
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Scarfe, Bradley Edward. "Oceanographic Considerations for the Management and Protection of Surfing Breaks." The University of Waikato, 2008. http://hdl.handle.net/10289/2668.
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Although the physical characteristics of surfing breaks are well described in the literature, there is little specific research on surfing and coastal management. Such research is required because coastal engineering has had significant impacts to surfing breaks, both positive and negative. Strategic planning and environmental impact assessment methods, a central tenet of integrated coastal zone management (ICZM), are recommended by this thesis to maximise surfing amenities. The research reported here identifies key oceanographic considerations required for ICZM around surfing breaks including: surfing wave parameters; surfing break components; relationship between surfer skill, surfing manoeuvre type and wave parameters; wind effects on waves; currents; geomorphic surfing break categorisation; beach-state and morphology; and offshore wave transformations. Key coastal activities that can have impacts to surfing breaks are identified. Environmental data types to consider during coastal studies around surfing breaks are presented and geographic information systems (GIS) are used to manage and interpret such information. To monitor surfing breaks, a shallow water multibeam echo sounding system was utilised and a RTK GPS water level correction and hydrographic GIS methodology developed. Including surfing in coastal management requires coastal engineering solutions that incorporate surfing. As an example, the efficacy of the artificial surfing reef (ASR) at Mount Maunganui, New Zealand, was evaluated. GIS, multibeam echo soundings, oceanographic measurements, photography, and wave modelling were all applied to monitor sea floor morphology around the reef. Results showed that the beach-state has more cellular circulation since the reef was installed, and a groin effect on the offshore bar was caused by the structure within the monitoring period, trapping sediment updrift and eroding sediment downdrift. No identifiable shoreline salient was observed. Landward of the reef, a scour hole ~3 times the surface area of the reef has formed. The current literature on ASRs has primarily focused on reef shape and its role in creating surfing waves. However, this study suggests that impacts to the offshore bar, beach-state, scour hole and surf zone hydrodynamics should all be included in future surfing reef designs. More real world reef studies, including ongoing monitoring of existing surfing reefs are required to validate theoretical concepts in the published literature.
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Tran, Ngan. "The impact of hydrodynamic coupling on the performance of multi-mode wave energy converters." Thesis, 2021. https://hdl.handle.net/2440/135690.
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Recently, research interest has deepened in developing technologies that are capable of generating electricity from renewable sources. Ocean wave energy is one such source, and is gaining attention due to its high energy density and favourable variability properties compared to other sources such as solar and wind. Although many Wave Energy Converter (WEC) prototypes have been proposed over the years, there is still no convergence on the best design. An emerging subset of WEC designs are ‘multi-mode converters’, which are capable of absorbing power from multiple hydrodynamic modes. This allows them to generate more energy from incoming waves compared to most other WECs, which typically use only one Degree-of-Freedom (DOF) for power absorption. However, one of the key challenges in the design and control of multi-mode WECs is the strong coupling between hydrodynamic modes, which can potentially lead to sub-optimal performance. The effect of this coupling on the device performance may also be further exacerbated when nonlinear hydrodynamic effects are considered. This thesis is dedicated to building an understanding of the impact of nonlinear coupling between hydrodynamic modes on the power absorption efficacy of a submerged, multi-mode, point absorber WEC with a flat cylindrical geometry. From this, the project also intends to provide general recommendations regarding the control and design of multi-mode WECs for increased performance. Three specific research questions were investigated: (i) what is the effect of nonlinear hydrodynamic coupling forces, caused by the change in projected surface area with large pitch motions, on the performance of multi-mode WECs, (ii) how should the surge, heave and pitch hydrodynamic modes be tuned to enhance the performance of WECs subjected to nonlinear coupling forces and (iii) what design parameters can be implemented to passively tune the hydrodynamic modes in a nonlinear, under-actuated WEC device. To address these questions, various numerical models were developed and compared, ranging from low fidelity models in the frequency-domain based on linear hydrodynamic models, to a weakly nonlinear hydrodynamic code based on the weak-scatterer approximation. Initially, it was necessary to gain a fundamental understanding of the nonlinear hydrodynamic forces acting on a device forced to undergo large pitch motions and oscillate in multiple hydrodynamic modes simultaneously. To this end, initial investigations assumed a simple WEC system with fully idealised kinematic control, wherein the pitch and surge motions could be explicitly defined. It was found that simultaneous surge and pitch motions changed the radiation forces acting on the WEC, resulting in significant reductions to the maximum power that could be absorbed by the device. Different approaches for adjusting the dynamics and resonance behaviour of the multi-mode WEC through tuning of the hydrodynamic modes were then investigated. Under the effects of nonlinear coupling between hydrodynamic modes, tuning the surge, heave and pitch modes to the same natural frequency was demonstrated to result in significant reductions in power absorbed, especially when the pitch amplitude was high. Recommendations were therefore made to decouple these modes when developing multi-mode WECs in the case where the design does not limit large pitch amplitudes. From the models investigated, this tuning approach also demonstrated a potential for improving the broadband power absorption efficacy of the device in irregular waves. In the final stage of this project, the impact of nonlinear coupling in an under-actuated system was investigated. A sensitivity study was conducted to investigate the effect of adjusting the geometric design of a three-tethered WEC on the resonance behaviour of each hydrodynamic mode. It was concluded that for maximum power absorption, two out of three of the device’s planar rigid body modes should be utilised to harvest energy from incident waves. Furthermore, for this WEC geometry and design, these rigid body modes should contain predominantly surge and heave motions. Subharmonic excitations caused by nonlinear forces arising from the tether arrangement and hydrodynamic interactions were also found to significantly reduce the performance of the device compared to the predictions from linear theory. It was determined that the power absorbed by the device was most sensitive to the arrangement of the tethers, while adjusting parameters related to the mass distribution resulted in little benefit to the overall device performance.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2022
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Humphrey, Michael Joseph. "Calculation of coupling between tapered fiber modes and whispering-gallery modes of a spherical microlaser." 2004. http://digital.library.okstate.edu/etd/umi-okstate-1077.pdf.
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Islam, Rubaiyat. "Theory and Applications of Microstrip/Negative-refractive-index Transmission Line (MS/NRI-TL) Coupled-line Couplers." Thesis, 2011. http://hdl.handle.net/1807/31789.
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The electromagnetic coupling of a microstrip transmission line (MS-TL) to a metamaterial backward wave Negative-Refractive-Index transmission line (NRI-TL) is the primary investigation of this dissertation. The coupling of forward waves in the MS-TL to the backward waves in the NRI-TL results in the formation of complex modes, characterized by simultaneous phase progression and attenuation along the lossless lines.
Through network-theoretic considerations, we investigate the properties of these modes in the complex-frequency plane of the Laplace domain to help unravel the confusion that has existed in the literature regarding the independent excitation of a pair of conjugate complex modes. We show that it is possible to arbitrarily suppress one of the modes over a finite bandwidth and completely eliminate it at a discrete set of frequencies using proper source and load impedances. Hence we use conjugate modes with independent amplitudes in our eigenmode expansion when we analyse various coupling configurations between the two types of lines (MS/NRI-TL coupler).
We derive approximate closed-form expression for the scattering parameters of the MS/NRI-TL coupler and these are complemented by design charts that allow the synthesis of a wide range of specifications. Moreover, these expressions reveal that such couplers allow for arbitrary backward coupling levels along with very high-isolation when they are made half a guided wavelength long. The MS/NRI-TL coupler offers some interesting applications which we highlight through the design and testing of a 3-dB power splitter, a high-directivity signal monitor and a compact corporate power divider. We have included design, simulation and experimental data for the fabricated prototypes exhibiting good agreement and thereby justifying the theory that has been developed in this work to explain the coupling between a right-handed MS-TL and a left-handed NRI-TL.
Books on the topic "Coupling between hydrodynamic modes"
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Janssen, Ted, Gervais Chapuis, and Marc de Boissieu. Physical properties. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198824442.003.0005.
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Physical properties of aperiodic crystals present some theoretical challenges due to the lack of three-dimensional periodicity. For the description of the structure there is a periodic representation in higher-dimensional space. For physical properties, however, this scheme cannot be used because the mapping between interatomic forces and the high-dimensional representation is not straightforward. In this chapter methods are described to deal with these problems. First, the hydrodynamic theory of aperiodic crystals and then the phonons and phasons theory are developed and illustrated with some examples. The properties of electrons in aperiodic crystals are also presented. Finally, the experimental findings of phonon and phason modes for modulated and quasicrystals are presented. The chapter also discusses diffuse scattering, the Debye–Waller factor, and electrical conductivity.
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Nagaosa, N. Multiferroics. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0010.
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This chapter delves into the physics of multiferroics, the recent developments of which are discussed here from the viewpoint of the spin current and “emergent electromagnetism” for constrained systems. It presents the three sources of U(1) gauge fields, namely, the Berry phase associated with the noncollinear spin structure, the spin-orbit interaction (SOI), and the usual electromagnetic field. The chapter reviews multiferroic phenomena in noncollinear magnets from this viewpoint and discusses theories of multiferroic behavior of cycloidal helimagnets in terms of the spin current or vector spin chirality. Relativistic SOI leads to a coupling between the spin current and the electric polarization, and hence the ferroelectric and dielectric responses are a new and important probe for the spin states and their dynamical properties. Microscopic theories of the ground state polarization for various electronic configurations, collective modes including the electromagnon, and some predictions including photoinduced chirality switching are discussed with comparison to experimental results.
Book chapters on the topic "Coupling between hydrodynamic modes"
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Nicolis, G., A. Puhl, and V. Altares. "Chemical Instabilities in a Non-Uniform Environment: Coupling Between Hydrodynamic and Chemical Modes." In Chemical Reactivity in Liquids, 401–14. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1023-5_34.
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Sharanya, S., and T. Sonamani Singh. "Hydrodynamic Coupling Between Comoving Microrobots." In Modeling, Simulation and Optimization, 77–84. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0836-1_6.
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Kumar, B., and P. Venkatakrishnan. "Flare-Driven Acoustic Modes in the Sun." In Magnetic Coupling between the Interior and Atmosphere of the Sun, 405–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02859-5_41.
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Roberts, J. W., and J. Z. Zhang. "Some Substantial Effects of Nonlinear Coupling between Modes of Vibration." In Industrial Vibration Modelling, 185–96. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4480-0_13.
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Mathur, S., R. A. García, and A. Eff-Darwich. "Low-Degree High-Frequency p and g Modes in the Solar Core." In Magnetic Coupling between the Interior and Atmosphere of the Sun, 364–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02859-5_32.
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Vietze, Laura, Mischa Bonn, and Maksim Grechko. "Two-Dimensional Terahertz-Infrared-Visible Spectroscopy Elucidates Coupling Between Low- and High-Frequency Modes." In Springer Series in Optical Sciences, 197–214. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-9753-0_9.
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Barbouche, N., E. Olmos, E. Guedon, and A. Marc. "Coupling Between Cell Kinetics and CFD to Establish Physio-Hydrodynamic Correlations in Various Stirred Culture Systems." In Cells and Culture, 213–17. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-3419-9_36.
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Krauzman, M., J. Breitenstein, and R. M. Pick. "Coupling Between Charge Transfer and Intramolecular Vibrational Modes in (TMTSF)2X, X = PF6 or ReO4." In Laser Optics of Condensed Matter, 339–46. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3726-7_46.
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Pleiner, Harald, and Helmut R. Brand. "The Coupling Between Phason and Soft Modes Near the Smectic C* to Smectic a Phase Transition." In Geometry and Thermodynamics, 447–51. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4615-3816-5_40.
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Meeker, Michael A., Chase T. Ellis, Joseph G. Tischler, Alexander J. Giles, Orest J. Glemboki, Dmitry N. Chigrin, Francisco J. Bezares, Richard Kasica, Loretta Shirey, and Joshua D. Caldwell. "Strong Coupling Effects Between IR-Inactive Zone Folded LO Phonon and Localized Surface Phonon Polariton Modes in SiC Nanopillars." In NATO Science for Peace and Security Series B: Physics and Biophysics, 417–18. Dordrecht: Springer Netherlands, 2018. http://dx.doi.org/10.1007/978-94-024-1544-5_40.
Full textConference papers on the topic "Coupling between hydrodynamic modes"
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Ayala, Luis F., Eltohami S. Eltohami, and Michael A. Adewumi. "Avoiding Pitfalls in Multiphase Thermo-Hydrodynamic Coupling." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/prod-29120.
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Multiphase flow is prevalent in many industrial processes. Therefore, accurate and efficient modeling of multiphase flow is essential to the understanding of these processes as well as the development of technologies to handle and manage them. In the petroleum industry, the occurrence and consequence thereof associated with such hydrodynamic processes are encountered in offshore facilities, surface facilities as well as reservoir applications. In this paper, we consider the modeling of these processes with special consideration to the transport of petroleum products through pipelines. Multiphase hydrodynamic modeling is usually a trade-off between maximizing the accuracy level while minimizing the computational time required. The most fundamental modeling effort developed to achieve this goal is based on applying simplifications to the basic physical laws, as defined by continuum mechanics, governing these processes. However, the modeling of multiphase flow processes requires the coupling of these basic laws with a thermodynamic phase behavior model. This paper highlights the impact of the techniques used to computationally couple the system’s thermodynamics with its fluid mechanics while paying close attention to the trade off mentioned above. It will consider the consequences of the simplifications applied, as well as inherent deficiencies associated with such simplifications. Special consideration is given to the conservation of mass as well as the terms that govern its transfer between the phases. Furthermore, the implications related to the common simplification of isothermal conditions are studied, highlighting the loss of accuracy in the material balance associated with this computational time-saving assumption. This paper concludes by suggesting remedies to these problems, supported by results, showing considerable improvement in fulfilling both the basic constrains which are minimizing time and maximizing accuracy.
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Hermundstad, Elin Marita, Jan Roger Hoff, Nuno Fonseca, and Rune Bjørkli. "Wave-Current Interaction Effects on Airgap Calculations." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62548.
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The importance of wave-current interaction effects on the determination of mean drift forces on floating offshore structures is well documented. Wave-current interaction effects will also influence the first-order motions and loads as well as the diffracted and radiated waves around the structure. One of the significant contributions to the influence of wave-current interaction effects on the motion responses is the additional coupling between motion modes due to the current. These effects are well known from seakeeping calculations of ships with forward speed. A structure with fore-aft symmetry will have no hydrodynamic coupling between heave and pitch in regular waves only. Due to the presence of a current, the symmetry of the flow around the body is lost, resulting in hydrodynamic coupling between the modes. This will also occur for a moored structure with slowly varying motions in the horizontal plane. The most important couplings are from the heave motion into pitch and surge and from heave to roll and sway. These couplings are otherwise present only for asymmetric structures. Due to the presence of the heave resonance and cancellation periods, the motion responses in roll and pitch for a semi-submersible will be influenced by the wave-current interaction effects. Due to the differences in phase between the different motion modes, the hydrodynamic coupling may have significant influence on the rotational motions roll and pitch and thus significant influence on the prediction of airgap. This coupling between the heave and roll/pitch modes due to the current adds complexity to the numerical simulations since the structure responses are more sensitive to the actual orientation of the structure, mooring configuration etc. A three-dimensional linear potential flow code, MULDIF, has been developed by SINTEF Ocean. This code accounts for hydrodynamic interaction between waves and current from arbitrary directions. The code can be applied to single or multiple bodies in infinite or finite water depth. Verification studies have previously shown good agreement with other numerical codes, Hermundstad et.al. [1], Zhiyuan et.al [2]. Validation studies with emphasis on airgap and comparison with experimental results are presented and numerical results for airgap and upwell are visualized and discussed. It is demonstrated how MULDIF can be used in airgap studies.
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Ravinthrakumar, Senthuran, Trygve Kristiansen, and Babak Ommani. "On the Hydrodynamic Interaction Between Ship and Free-Surface Motions on Vessels With Moonpools." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95932.
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Abstract Coupling between moonpool resonance and vessel motion is investigated in two-dimensional and quasi three-dimensional settings, where the models are studied in forced heave and in freely floating conditions. The two-dimensional setups are with a recess, while the quasi three-dimensional setups are without recess. One configuration with recess is presented for the two-dimensional case, while three different moonpool sizes (without recess) are tested for the quasi three-dimensional setup. A large number of forcing periods, and three wave steepnesses are tested. Boundary Element Method (BEM) and Viscous BEM (VBEM) time-domain codes based on linear potential flow theory, and a Navier–Stokes solver with linear free-surface and body-boundary conditions, are implemented to investigate resonant motion of the free-surface and the model. Damping due to flow separation from the sharp corners of the moonpool inlets is shown to matter for both vessel motions and moonpool response around the piston mode. In general, the CFD simulations compare well with the experimental results. BEM over-predicts the response significantly at resonance. VBEM provides improved results compared to the BEM, but still over-predicts the response. In the two-dimensional study there are significant coupling effects between heave, pitch and moonpool responses. In the quasi three-dimensional tests, the coupling effect is reduced significantly as the moonpool dimensions relative to the displaced volume of the ship is reduced. The first sloshing mode is investigated in the two-dimensional case. The studies show that damping due to flow separation is dominant. The vessel motions are unaffected by the moonpool response around the first sloshing mode.
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Zhang, Ning, Puxuan Li, and Anpeng He. "Coupling of 1-D and 2-D Hydrodynamic Models Using an Immersed-Boundary Method." In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72113.
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Numerical simulations of flooding events through rivers and channels require coupling between 1-D and 2-D hydrodynamic models. The rivers and channels are relatively narrow and the widths are smaller than the grid resolution of the 2-D model. The shapes of the rivers and channels are complex and do not necessarily coincide with the grid points. The coupling between the 1-D and 2-D models are challenging. In this paper, a novel Immersed-Boundary (IB) type coupling is implemented. Using this method, no linkpoint needs to be manually determined, nor does the discharge boundary conditions need to be specified on the linkpoints. The linkpoints will be dynamically determined by comparing the water levels in the 1-D channel and the surrounding dry cell elevations in the 2-D model. The linkpoint flow conditions thus can be dynamically calculated by the IB type of implementation. This coupling method enables more realistic simulations of water exchange between channels and dry lands during a flooding event comparing to the traditional coupling method.
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Zhu, Liqun, Milind Bhagavat, and Imin Kao. "Analysis of the Interaction Between Thin-Film Fluid Hydrodynamics and Wire Vibration in Wafer Manufacturing Using Wiresaw." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2269.
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Abstract In free abrasive wafer slicing process (FAM) using wiresaw, hydrodynamic pressure exerted by the thin slurry film is crucial to the process of cutting and material removal from substrate surface. It affects the process quality by introducing viscous damping effect to the transverse motion of the wire. The pressure distribution in the slurry film is subjected to the interaction of multi-physical phenomena induced in the wire-saw cutting process, including the axially moving wire transverse vibration under high tension (20N to 35N), as well as the hydrodynamic lubrication behavior of the thin slurry film. In this paper, the interaction between thin-film hydrodynamics and wire vibration is modeled using the coupling of basic Reynold’s equation for fluid lubrication and the dynamic equation describing the transverse vibration of the translating wire. The time-variant hydrodynamic pressure field is used to obtain the dynamic damping force exerted on the wire by the thin slurry film. A computational model is constructed and typical parametric studies are conducted based on the simulation results. Numerical scheme of semi-discretization is carried out to simulate the dynamic multi-disciplinary model. Galerkin method of weighted residual is used to carry out the spatial finite element discretization of the governing non-linear partial differential equations of the system with certain boundary conditions. In addition, Newmark method is applied to perform the time integration of the semi-discretized computational model from initial conditions. The direct numerical simulation dynamically yields the profile of the slurry hydrodynamic pressure distribution and the wire vibration response as functions of process parameters, such as the static film thickness of the slurry flow, wire translating speed and wire tension. From the simulation results, it is shown that the presence of the slurry film in the wiresaw process is important in eliminating the undesirable vibration modes and reducing the amplitude of wire vibration.
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Judge, Carolyn Q. "Coupling of Heave and Roll for High-Speed Planing Hulls." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23261.
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For planing hulls, dynamic lift reduces the submergence of the hull, allowing small motions to result in large changes in hydrodynamic forces and moments. The dynamic lift forces acting on the bottom of a planing hull dominate the hydrodynamics and these lift forces are known to depend on speed and wetted surface. As a planing boat rolls the wetted surface changes, which affects the dynamic lift. A series of tests using a wooden prismatic planing hull model with a constant deadrise of 20 degrees were done at static heel and heave positions as well as oscillating heave conditions. This paper presents the results from these experiments, primarily looking at the hydrodynamic coefficients in heave as a function of heel angle and exploring the coupling between these motions for a prismatic high-speed planing hull.
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Wang, Weizhi, Csaba Pákozdi, Arun Kamath, Tobias Martin, and Hans Bihs. "Hydrodynamic Coupling of Viscous and Non-Viscous Numerical Wave Solutions Within the Open-Source Hydrodynamics Framework REEF3D." In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-62185.
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Abstract A comprehensive understanding of the marine environment in the offshore area requires phase-resolved wave information. For the far-field wave propagation, computational efficiency is crucial, as large spatial and temporal scales are involved. For the near-field extreme wave events and wave impacts, high resolution is required to resolve the flow details and turbulence. The combined use of a computationally efficient large-scale model and a high-resolution local-scale solver provides a solution the combines accuracy and efficiency. This article introduces a coupling strategy between the efficient fully nonlinear potential flow (FNPF) solver REEF3D::FNPF and the high-fidelity computational fluid dynamics (CFD) model REEF3D::CFD within in the open-source hydrodynamics framework REEF3D. REEF3D::FNPF solves the Laplace equation together with the boundary conditions on a sigma-coordinate. The free surface boundary conditions are discretised using high-order finite difference methods. The Laplace equation for the velocity potential is solved with a conjugated gradient solver preconditioned with geometric multi-grid provided by the open-source library hypre. The model is fully parallelised following the domain decomposition strategy and the MPI protocol. The waves calculated with the FNPF solver are used as wave generation boundary condition for the CFD based numerical wave tank REEF3D::CFD. The CFD model employs an interface capturing two-phase flow approach that can resolve complex wave structure interaction, including breaking wave kinematics and turbulent effects. The presented hydrodynamic coupling strategy is tested for various wave conditions and the accuracy is fully assessed.
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Karmarker, Ashwini, Jacqueline O’Connor, and Isaac Boxx. "Relative Effects of Velocity- and Mixture-Coupling in a Thermoacoustically Unstable, Partially-Premixed Flame." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59113.
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Abstract Combustion instability, which is the result of a coupling between combustor acoustic modes and unsteady flame heat release rate, is a severely limiting factor in the operability and performance of modern gas turbine engines. This coupling can occur through different coupling pathways, such as flow field fluctuations or equivalence ratio fluctuations. In realistic combustor systems, there are complex hydrodynamic and thermo-chemical processes involved, which can lead to multiple coupling pathways. In order to understand and predict the mechanisms that govern the onset of combustion instability in real gas turbine engines, we consider the influences that each of these coupling pathways can have on the stability and dynamics of a partially-premixed, swirl-stabilized flame. In this study, we use a model gas turbine combustor with two concentric swirling nozzles of air, separated by a ring of fuel injectors, operating at an elevated pressure of 5 bar. The flow split between the two streams is systematically varied to observe the impact on the flow and flame dynamics. High-speed stereoscopic particle image velocimetry, OH planar laser-induced fluorescence, and acetone planar laser-induced fluorescence are used to obtain information about the velocity field, flame, and fuel-flow behavior, respectively. Depending on the flow conditions, a thermoacoustic oscillation mode or a hydrodynamic mode, identified as the precessing vortex core, is present. The focus of this study is to characterize the mixture coupling processes in this partially-premixed flame as well as the impact that the velocity oscillations have on mixture coupling. Our results show that, for this combustor system, changing the flow split between the two concentric nozzles can alter the dominant harmonic oscillation modes in the system, which can significantly impact the dispersion of fuel into air, thereby modulating the local equivalence ratio of the flame. This insight can be used to design instability control mechanisms in real gas turbine engines.
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Arthurs, David, and Samir Ziada. "The Effect of Fluid-Resonant Coupling in High-Speed Impinging Planar Jet Flows." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97141.
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This study investigates the effect of fluid-resonant coupling, i.e. the coupling between unstable modes of an impinging jet with resonant acoustic modes occurring between the nozzle and the impingement surface, on the self-excited oscillations of high-speed impinging planar jet. In order to investigate this phenomenon, a series of experiments have been performed using a high-speed impinging planar jet with varying nozzle thickness (h) and impingement distance (xo), for a single Mach number in the compressible flow regime. The test results reveal that the jet oscillation is controlled by a fluid-dynamic mechanism for small impingement distances, where the unstable mode of the jet is controlled by the impingement ratio. At larger impingement distances, the response is dominated by a fluid-resonant mechanism, in which the various hydrodynamic modes of the jet couple with different resonant acoustic modes occurring between the nozzle and the impingement surface. Within the fluid-resonant regime the system produces acoustic tones that are excited predominantly as a function of the impingement distance, with the nozzle thickness and impingement ratio having only minor effects on the tone frequency. Flow visualization images show that the same unstable mode is excited for multiple nozzle thicknesses at a constant impingement distance, despite the wide variations in associated impingement ratio.
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Lee, C. Y., and R. S. Cant. "CFD Investigation of Hydrodynamic and Acoustic Instabilities of Bluff-Body Stabilized Turbulent Premixed Flames." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25507.
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Combustion instabilities in propulsion systems are often manifested through high amplitude pressure oscillations that can severely compromise performance and even lead to mechanical failure. Such instability arises from the development of large-scale coherent structures and their breakdown into fine scale turbulence that can alter the flame structure and affect turbulent mixing. When in phase with the pressure, the modulated heat release rate fluctuations can drive the system to the point where it reaches a limit cycle. Using high fidelity CFD, the present investigation describes the occurrence of combustion-driven instability in bluff-body stabilized turbulent premixed flames, in which there is dynamic coupling between the preferred hydrodynamic modes and the acoustics of the duct. A URANS approach is adopted, using a second moment closure to solve for the anisotropic turbulent Reynolds stresses. This is combined with the Bray-Moss-Libby (BML) combustion model with a modified reaction rate closure that aims to capture the changes in the flame surface density due to external flow perturbations. Two different geometries are used for the investigation: the first is a laboratory-scale planar bluff-body flameholder [1]; and the second is the well-known Volvo afterburner experiment [2]. Four different conditions are presented to illustrate the various self-excited instabilities that can appear depending on the coupling mechanisms between the different fluid-mechanical and acoustic phenomena. For the planar geometry, a self-sustained hydrodynamic instability induced by large-scale coherent structures occurs under fuel-lean conditions. When the equivalence ratio is increased, the flame becomes strongly wrinkled due to velocity perturbations arising from the Kelvin-Helmholtz (K-H) instability of the shear layer. The combustion heat release becomes modulated such that its phase relationship with the pressure fluctuations is sufficient to trigger thermoacoustic instability. For the Volvo experiment, symmetric shedding takes place and an acoustic mode of the duct is excited when the mixture strength is lean. At higher equivalence ratio, the flame is perturbed by the hydrodynamic instabilities of the most amplified mode. Small scale structures can be seen in the vicinity of the flameholder, and larger fluctuations in the flame occur further downstream. No appreciable feedback from the acoustic modes is present to sustain combustion instabilities.