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Relevant bibliographies by topics / Heat flow harmonic maps

Academic literature on the topic 'Heat flow harmonic maps'

Author: Grafiati

Published: 10 December 2022

Last updated: 29 January 2023

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Journal articles on the topic "Heat flow harmonic maps"

1

Wang, Changyou, and Tao Huang. "On uniqueness of heat flow of harmonic maps." Indiana University Mathematics Journal 65, no. 5 (2016): 1525–46. http://dx.doi.org/10.1512/iumj.2016.65.5894.

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Coron, J. M. "Nonuniqueness for the heat flow of harmonic maps." Annales de l'Institut Henri Poincare (C) Non Linear Analysis 7, no. 4 (July 1990): 335–44. http://dx.doi.org/10.1016/s0294-1449(16)30295-5.

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Wang, Meng, and Xiao-feng Liu. "Heat flow of harmonic maps from noncompact manifolds." Applied Mathematics-A Journal of Chinese Universities 23, no. 4 (December 2008): 431–36. http://dx.doi.org/10.1007/s11766-008-1604-z.

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Xin, Yuanlong. "Heat flow of equivariant harmonic maps from 𝔹3into ℂℙ2." Pacific Journal of Mathematics 176, no. 2 (December 1, 1996): 563–79. http://dx.doi.org/10.2140/pjm.1996.176.563.

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LI, JIAYU, and SILEI WANG. "THE HEAT FLOW OF HARMONIC MAPS FROM NONCOMPACT MANIFOLDS." Chinese Annals of Mathematics 21, no. 01 (January 2000): 121–30. http://dx.doi.org/10.1142/s0252959900000169.

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Huang, Pingliang, and Hongyan Tang. "On the heat flow of -harmonic maps from into." Nonlinear Analysis: Theory, Methods & Applications 67, no. 7 (October 2007): 2149–56. http://dx.doi.org/10.1016/j.na.2006.09.020.

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Wang, Meng. "The heat flow of harmonic maps from noncompact manifolds." Nonlinear Analysis: Theory, Methods & Applications 71, no. 3-4 (August 2009): 1042–48. http://dx.doi.org/10.1016/j.na.2008.11.029.

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Kung-Ching, Chang. "Heat flow and boundary value problem for harmonic maps." Annales de l'Institut Henri Poincare (C) Non Linear Analysis 6, no. 5 (September 1989): 363–95. http://dx.doi.org/10.1016/s0294-1449(16)30316-x.

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Wang, Jiaping. "The heat flow and harmonic maps between complete manifolds." Journal of Geometric Analysis 8, no. 3 (September 1998): 485–514. http://dx.doi.org/10.1007/bf02921799.

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Chen, Yunmei, Min-Chun Hong, and Norbert Hungerbühler. "Heat flow ofp-harmonic maps with values into spheres." Mathematische Zeitschrift 215, no. 1 (January 1994): 25–35. http://dx.doi.org/10.1007/bf02571698.

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Dissertations / Theses on the topic "Heat flow harmonic maps"

1

Wittmann, Johannes [Verfasser], and Bernd [Akademischer Betreuer] Ammann. "The heat flow for Dirac-harmonic maps / Johannes Wittmann ; Betreuer: Bernd Ammann." Regensburg : Universitätsbibliothek Regensburg, 2018. http://d-nb.info/1172970602/34.

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Branding, Volker. "The evolution equations for Dirac-harmonic Maps." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6420/.

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This thesis investigates the gradient flow of Dirac-harmonic maps. Dirac-harmonic maps are critical points of an energy functional that is motivated from supersymmetric field theories. The critical points of this energy functional couple the equation for harmonic maps with spinor fields. At present, many analytical properties of Dirac-harmonic maps are known, but a general existence result is still missing. In this thesis the existence question is studied using the evolution equations for a regularized version of Dirac-harmonic maps. Since the energy functional for Dirac-harmonic maps is unbounded from below the method of the gradient flow cannot be applied directly. Thus, we first of all consider a regularization prescription for Dirac-harmonic maps and then study the gradient flow. Chapter 1 gives some background material on harmonic maps/harmonic spinors and summarizes the current known results about Dirac-harmonic maps. Chapter 2 introduces the notion of Dirac-harmonic maps in detail and presents a regularization prescription for Dirac-harmonic maps. In Chapter 3 the evolution equations for regularized Dirac-harmonic maps are introduced. In addition, the evolution of certain energies is discussed. Moreover, the existence of a short-time solution to the evolution equations is established. Chapter 4 analyzes the evolution equations in the case that the domain manifold is a closed curve. Here, the existence of a smooth long-time solution is proven. Moreover, for the regularization being large enough, it is shown that the evolution equations converge to a regularized Dirac-harmonic map. Finally, it is discussed in which sense the regularization can be removed. In Chapter 5 the evolution equations are studied when the domain manifold is a closed Riemmannian spin surface. For the regularization being large enough, the existence of a global weak solution, which is smooth away from finitely many singularities is proven. It is shown that the evolution equations converge weakly to a regularized Dirac-harmonic map. In addition, it is discussed if the regularization can be removed in this case.
Die vorliegende Dissertation untersucht den Gradientenfluss von Dirac-harmonischen Abbildungen. Dirac-harmonische Abbildungen sind kritische Punkte eines Energiefunktionals, welches aus supersymmetrischen Feldtheorien motiviert ist. Die kritischen Punkte dieses Energiefunktionals koppeln die Gleichung für harmonische Abbildungen mit Spinorfeldern. Viele analytische Eigenschaften von Dirac-harmonischen Abbildungen sind bereits bekannt, ein allgemeines Existenzresultat wurde aber noch nicht erzielt. Diese Dissertation untersucht das Existenzproblem, indem der Gradientenfluss von einer regularisierten Version Dirac-harmonischer Abbildungen untersucht wird. Die Methode des Gradientenflusses kann nicht direkt angewendet werden, da das Energiefunktional für Dirac-harmonische Abbildungen nach unten unbeschränkt ist. Daher wird zunächst eine Regularisierungsvorschrift für Dirac-harmonische Abbildungen eingeführt und dann der Gradientenfluss betrachtet. Kapitel 1 stellt für die Arbeit wichtige Resultate über harmonische Abbildungen/harmonische Spinoren zusammen. Außerdem werden die zur Zeit bekannten Resultate über Dirac-harmonische Abbildungen zusammengefasst. In Kapitel 2 werden Dirac-harmonische Abbildungen im Detail eingeführt, außerdem wird eine Regularisierungsvorschrift präsentiert. Kapitel 3 führt die Evolutionsgleichungen für regularisierte Dirac-harmonische Abbildungen ein. Zusätzlich wird die Evolution von verschiedenen Energien diskutiert. Schließlich wird die Existenz einer Kurzzeitlösung bewiesen. In Kapitel 4 werden die Evolutionsgleichungen für den Fall analysiert, dass die Ursprungsmannigfaltigkeit eine geschlossene Kurve ist. Die Existenz einer Langzeitlösung der Evolutionsgleichungen wird bewiesen. Es wird außerdem gezeigt, dass die Evolutionsgleichungen konvergieren, falls die Regularisierung groß genug gewählt wurde. Schließlich wird diskutiert, ob die Regularisierung wieder entfernt werden kann. Kapitel 5 schlussendlich untersucht die Evolutionsgleichungen für den Fall, dass die Ursprungsmannigfaltigkeit eine geschlossene Riemannsche Spin Fläche ist. Es wird die Existenz einer global schwachen Lösung bewiesen, welche bis auf endlich viele Singularitäten glatt ist. Die Lösung konvergiert im schwachen Sinne gegen eine regularisierte Dirac-harmonische Abbildung. Auch hier wird schließlich untersucht, ob die Regularisierung wieder entfernt werden kann.

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Huang, Tao. "REGULARITY AND UNIQUENESS OF SOME GEOMETRIC HEAT FLOWS AND IT'S APPLICATIONS." UKnowledge, 2013. http://uknowledge.uky.edu/math_etds/10.

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This manuscript demonstrates the regularity and uniqueness of some geometric heat flows with critical nonlinearity. First, under the assumption of smallness of renormalized energy, several issues of the regularity and uniqueness of heat flow of harmonic maps into a unit sphere or a compact Riemannian homogeneous manifold without boundary are established. For a class of heat flow of harmonic maps to any compact Riemannian manifold without boundary, satisfying the Serrin's condition, the regularity and uniqueness is also established. As an application, the hydrodynamic flow of nematic liquid crystals in Serrin's class is proved to be regular and unique. The natural extension of all the results to the heat flow of biharmonic maps is also presented in this manuscript.

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Topping, Peter. "The harmonic map heat flow from surfaces." Thesis, University of Warwick, 1996. http://wrap.warwick.ac.uk/50788/.

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We present a study of the harmonic map heat flow of Eells and Sampson in the case that the domain manifold is a surface. Particular emphasis has been placed on the singularities which may occur, as described by Struwe, and the analysis of the flow despite these. In Chapter 1 we give a brief introduction to the theory of harmonic maps and their flow. Further details are to be found in [9] and [10]. In the case that the domain manifold is a surface we describe the existence theory for the heat flow and the theory of bubbling. In Chapter 2 we investigate the question of the uniformity in time of the convergence of the heat flow to a bubble tree at infinite time. In Section (2.1) (page 28) we give the first example of a non-uniform flow. In contrast, Theorem (2.2) (page 30) provides conditions under which the convergence is uniform and any bubbles which form are rigid. In Chapter 3 we give the first example of a nontrivial bubble tree - in other words we give a flow in which more than one bubble develops at the same point at infinite time. In Chapter 4 we discuss in what sense two flows are close when their initial maps are close. We formulate this question in various ways, providing examples of instability and an `infinite time' stability result (Theorem (4.2), page 56) using techniques developed in Chapter 2. From the theory of bubbling as described in Chapter 1, if an initial map has less energy than is required for a bubble, then the subsequent flow cannot blow up. In Chapter 5 we ask conversely whether given enough energy for a bubble, we can find an initial map leading to blow-up. In the appendix we outline a plausible construction of a flow which can be analysed at two different sequences of times to give convergence to two different bubble trees, with different numbers of bubbles.

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Roxanas, Dimitrios. "Long-time dynamics for the energy-critical harmonic map heat flow and nonlinear heat equation." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61612.

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The main focus of this thesis is on critical parabolic problems, in particular, the harmonic map heat from the plane to S2, and nonlinear focusing heat equations with an algebraic nonlinearity. The focus of this work has been on long-time dynamics, stability and singularity formation, and the investigation of the role of special, soliton-like, solutions to the asymptotic behaviour of solutions. Harmonic Map Heat Flow: Flow: we consider m-corotational solutions to the harmonic map heat flow from R2 to S2. We first work in a class of maps with trivial topology and energy of the initial data below two times the energy of the stationary harmonic map solutions. We give a new proof of global existence and decay. The proof is based on the "concentration-compactness plus rigidity" approach of Kenig and Merle and relies on the dissipation of the energy and a profile decomposition. We also treat m-corotational maps (m greater than 3) with non-trivial topology and energy of the initial data less than three times the energy of the stationary harmonic map solutions. Through a new stability argument we rule out finite-time blow-up and show that the global solution asymptotically converges to a harmonic map. Nonlinear Heat Equation: we also study solutions of the focusing energy-critical nonlinear heat equation. We show that solutions emanating from initial data with energy and kinetic energy below those of the stationary solutions are global and decay to zero. To prove that global solutions dissipate to zero we rely on a refined small data theory, L2-dissipation and an approximation argument. We then follow the "concentration-compactness plus rigidity" roadmap of Kenig and Merle (and in particular the approach taken by Kenig and Koch for Navier-Stokes) to exclude finite-time blow-up.
Science, Faculty of
Mathematics, Department of
Graduate

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Wang, Lu Ph D. Massachusetts Institute of Technology. "Self-shrinkers of mean curvature flow and harmonic map heat flow with rough boundary data." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67817.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-63).
In this thesis, first, joint with Longzhi Lin, we establish estimates for the harmonic map heat flow from the unit circle into a closed manifold, and use it to construct sweepouts with the following good property: each curve in the tightened sweepout, whose energy is close to the maximal energy of curves in the sweepout, is itself close to a closed geodesic. Second, we prove the uniqueness for energy decreasing weak solutions of the harmonic map heat flow from the unit open disk into a closed manifold, given any H¹ initial data and boundary data, which is the restriction of the initial data on the boundary of the disk. Previously, under an additional assumption on boundary regularity, this uniqueness result was obtained by Rivière (when the target manifold is the round sphere and the energy of initial data is small) and Freire (for general target manifolds). The point of our uniqueness result is that no boundary regularity assumption is needed. Also, we prove the exponential convergence of the harmonic map heat flow, assuming that the energy is small at all times. Third, we prove that smooth self-shrinkers in the Euclidean space, that are entire graphs, are hyperplanes. This generalizes an earlier result by Ecker and Huisken: no polynomial growth assumption at infinity is needed.
by Lu Wang.
Ph.D.

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Triplett, Kimberly Ann. "Two-phase flow regime maps and pressure drop in microchannels." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16867.

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Jacobi, Christoph, and Daniel Mewes. "Heat flux classification of CMIP5 model results using self-organizing maps." Universität Leipzig, 2019. https://ul.qucosa.de/id/qucosa%3A74181.

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We used the self-organizing maps (SOMs) method on eight models that participated in the Coupled model intercomparison project phase 5 (CMIP5) and two different greenhouse gases (GHG) concentration experiments. The SOMs were created from the winter 500 hPa horizontal temperature flux for each model. The clustering by the SOM revealed that in addition to the three flux pathways found in reanalyses (Pacific, Atlantic and Siberian/continental pathway), superpositions of these occur for the free running climate models, which develop their dynamic more freely than the reanalyses. It was found that the general structure of fluxes is indirectly dependent on the GHG concentrations, as the derived results from SOM patterns are different between the two GHG concentrations. It is suggested that flux patterns change from stable cyclonic motion over the north pole to flux pathways that feature more meridional fluxes through the North Atlantic and North Pacific into the Arctic.
Die Methode der Self-Organizing Maps (SOMs) wurde auf acht CMIP5-Modelle mit jeweils zwei verschiedenen Treibhausgasszenarien angwendet. Die SOMs wurden für jedes Modell und jede der beiden Modelläufe für den horizontalen Temperaturfluss in 500 hPa im Winter erstellt. Zusätzlich zu den aus der Analyse von Reanalyse-Daten erwarteten drei Transportwegen (pazifisch, atlantisch und sibirisch/kontinental) wurden Überlagerungen dieser gefunden. Es konnte gezeigt werden, dass die grundsätzliche Struktur der Transporte indirekt abhängig von der Treibhausgaskonzentration ist. Die Ergebnisse deuten darauf hin, dass sich die generelle Struktur des atmosphärischen Transports von einer stabilen zyklonalen Bewegung über dem Nordpol sich zu Transporten verschiebt, welche meridionale Transporte über den Nortdatlantik und den Nordpazifik in die Arktis führen.

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Hineman, Jay Lawrence. "THE HYDRODYNAMIC FLOW OF NEMATIC LIQUID CRYSTALS IN R³." UKnowledge, 2012. http://uknowledge.uky.edu/math_etds/7.

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This manuscript demonstrates the well-posedness (existence, uniqueness, and regularity of solutions) of the Cauchy problem for simplified equations of nematic liquid crystal hydrodynamic flow in three dimensions for initial data that is uniformly locally L3(R3) integrable (L3U(R3)). The equations examined are a simplified version of the equations derived by Ericksen and Leslie. Background on the continuum theory of nematic liquid crystals and their flow is provided as are explanations of the related mathematical literature for nematic liquid crystals and the Navier–Stokes equations.

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Chen, Zhengxiang [Verfasser], and Guofang [Akademischer Betreuer] Wang. "Some topics on Dirac-harmonic maps and the Yang-Mills flow = Über Dirac-harmonische Abbildungen und über den Yang-Mills-Fluss." Freiburg : Universität, 2013. http://d-nb.info/1123476608/34.

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Books on the topic "Heat flow harmonic maps"

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Lin, Fanghua. The analysis of harmonic maps and their heat flows. Singapore: World Scientific, 2008.

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1967-, Wang Changyou, ed. The analysis of harmonic maps and their heat flows. Singapore: World Scientific, 2008.

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Topping, Peter Miles. The harmonic map heat flow from surfaces. [s.l.]: typescript, 1996.

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C, Ku Jerry, and United States. National Aeronautics and Space Administration., eds. Brief communication: Soot volume fraction maps for normal and reduced gravity laminar acetylene jet diffusion flames. [Washington, DC: National Aeronautics and Space Administration, 1997.

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C, Ku Jerry, and United States. National Aeronautics and Space Administration., eds. Brief communication: Soot volume fraction maps for normal and reduced gravity laminar acetylene jet diffusion flames. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Book chapters on the topic "Heat flow harmonic maps"

1

Grotowski, Joseph F. "Heat Flow for Harmonic Maps." In Nematics, 129–40. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3428-6_10.

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Gulliver, Robert. "Fiber Evolution in the Heat Flow of Harmonic Maps." In Nematics, 173–78. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3428-6_12.

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Yunmei, Chen, and Ding Wei-Yue. "Blow-Up Analysis for Heat Flow of Harmonic Maps." In Nematics, 49–64. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3428-6_5.

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Bethuel, Fabrice, Jean-Michel Coron, Jean-Michel Ghidaglia, and Alain Soyeur. "Heat Flows and Relaxed Energies for Harmonic Maps." In Nonlinear Diffusion Equations and Their Equilibrium States, 3, 99–109. Boston, MA: Birkhäuser Boston, 1992. http://dx.doi.org/10.1007/978-1-4612-0393-3_7.

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Struwe, Michael. "Heat-flow methods for harmonic maps of surfaces and applications to free boundary problems." In Lecture Notes in Mathematics, 293–319. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/bfb0100801.

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Jost, Jürgen. "The heat flow on manifolds. Existence and uniqueness of harmonic maps into nonpositively curved image manifolds." In Nonlinear Methods in Riemannian and Kählerian Geometry, 87–109. Basel: Birkhäuser Basel, 1988. http://dx.doi.org/10.1007/978-3-0348-7690-2_3.

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Jost, Jürgen. "The heat flow on manifolds. Existence and uniqueness of harmonic maps into nonpositively curved image manifolds." In Nonlinear Methods in Riemannian and Kählerian Geometry, 87–109. Basel: Birkhäuser Basel, 1991. http://dx.doi.org/10.1007/978-3-0348-7706-0_3.

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Chang, Kung-Ching, and Wei-Yue Ding. "A Result on the Global Existence for Heat Flows of Harmonic Maps from D 2into S 2." In Nematics, 37–47. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3428-6_4.

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Aamodt, L. C. "The Nature of Harmonic Heat Flow." In Photoacoustic and Photothermal Phenomena, 377–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-540-48181-2_99.

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Čermák, V., and R. Haenel. "Geothermal Maps." In Handbook of Terrestrial Heat-Flow Density Determination, 261–300. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2847-3_7.

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Conference papers on the topic "Heat flow harmonic maps"

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Guzma´n, Amador M., and Fernando A. Villar. "Flow Bifurcations and Heat Transfer Enhancement in Asymmetric Grooved Channels." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72314.

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Numerical investigations of the flow bifurcations, transition scenario and heat transfer enhancement in asymmetric grooved channels are performed by direct numerical simulations of the mass, momentum and energy equations. The governing equations are solved for laminar and time-dependent transitional flow regimes by the spectral element method in a periodic computational domain with appropriated boundary conditions. Numerical results show a flow transition scenario with two Hopf bifurcations B1 and B2, occurring in critical Reynolds numbers Rec1 y Rec2, respectively. Fundamental frequencies ω1 and ω2, and super harmonic combinations of both develop as the Reynolds number increases from a laminar to higher transitional flow regime. Numerical calculations demonstrate that the time-average mean Nusselt number (the non-dimensional heat transfer rate), increases significantly as the flow passes from a laminar to a periodic—and then to a quasi-periodic flow regime. This increase is accompanied by a reasonable increase in both the friction factor and the pumping power. The obtained behavior is comparable to other geometries and configurations as well as to previously reported numerical results for the studied geometry. This numerical investigation shows a transition scenario at the onset of turbulence, similar to the Ruelle-Takens-Newhouse scenario, which has not been found or reported by other researchers using this geometry. The numerical simulation results also show the existence of a bifurcation scenario that develops a path-dependent flow and heat transport behavior. In the vicinity of the first Hopf flow bifurcation (and consequently, the critical Reynolds number Rec1), the resulting stable time periodic flow depends on both the initial flow conditions and the way in which the incremental process to higher flow regimes is carried out.

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Hartmann, Daniel, Wolfgang Schro¨der, and Santosh Hemchandra. "Influence of Hydrodynamic Instability on the Heat Release Transfer Function of Premixed Flames." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22848.

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Gas expansion across the premixed flame surface causes deformations induced on the flame surface to grow in time due to hydrodynamical coupling between the unsteady flow and flame surface motions. This phenomenon is the well known hydro-dynamical instability (also know as the Darrieus-Landau (D-L) instability) of premixed flames. It is well established from several experimental studies that premixed flames subject to acoustic forcing distort and wrinkle under the influence of the unsteady velocity field generated by the forcing, thereby, changing its surface area and causing the net heat-release rate of the flame to oscillate. The D-L instability mechanism influences this heat-release oscillation through its influence on the underlying flame surface wrinkling. An understanding of this mechanism is necessary to develop reliable reduced-order modelling tools to predict the onset of combustion instabilities in Lean Premixed (LPM) systems. This paper presents a computational study of the influence of the D-L instability on the heat release transfer function of premixed flames subjected to harmonic velocity forcing. The effect of varying Markstein length and gas temperature ratio is presented. It is shown that when the induced flame surface perturbations are unstable w.r.t the D-L instability, the net heat release response is dominated by the oscillation in total burning area. In the stable case, the net response is due to the resultant of contributions from the net burning area oscillation as well as the area-averaged mass burning rate oscillation induced by unsteady spatial variations in laminar flame speed, sL. The boundary between these two response regimes is determined by the Markstein number for which flame surface perturbations are neutrally stable.

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Guyot, Daniel, and Christian Oliver Paschereit. "Active Control of Combustion Instability Using Symmetric and Asymmetric Premix Fuel Modulation." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27342.

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Active instability control was applied to an atmospheric swirl-stabilized premixed combustor using open loop and closed loop control schemes. Actuation was realised by two on-off valves allowing for symmetric and asymmetric modulation of the premix fuel flow while maintaining constant time averaged overall fuel mass flow. Pressure and heat release fluctuations in the combustor as well as NOx, CO and CO2 emissions in the exhaust were recorded. In the open loop circuit the heat release response of the flame was first investigated during stable combustion. For symmetric fuel modulation the dominant frequency in the heat release response was the modulation frequency, while for asymmetric modulation it was its first harmonic. In stable open loop control a reduction of NOx emissions due to fuel modulation of up to 19% was recorded. In the closed loop mode phase-shift control was applied while triggering the valves at the dominant oscillation frequency as well as at its second subharmonic. Both, open and closed loop control schemes were able to successfully control a low-frequency combustion instability, while showing only a small increase in NOx emissions compared to, for example, secondary fuel modulation. Using premixed open loop fuel modulation, attenuation was best when modulating the fuel at frequencies different from the dominant instability frequency and its subharmonic. The performance of asymmetric fuel modulation was generally slightly better than for symmetric modulation in terms of suppression levels as well as emissions. Suppression of the instability’s pressure rms level of up to 15.7 dB was recorded.

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De Paepe, Michel, Marijn Billiet, Steven Lecompte, and Alihan Kaya. "VOID FRACTION MEASUREMENTS IN GAS-LIQUID FLOW AND HOW TO USE THEM FOR PROBABILISTIC FLOW MAPS FOR EVAPORATING REFRIGERANTS." In International Heat Transfer Conference 16. Connecticut: Begellhouse, 2018. http://dx.doi.org/10.1615/ihtc16.kn.000022.

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Murari, Sridhar, Sunnam Sathish, Ramakumar Bommisetty, and Jong S. Liu. "CFD Analyses of a Single Stage Turbine With Inlet Hot-Streak at Different Circumferential Locations." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94141.

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This paper presents a detailed flow and heat transfer characteristic analysis on a gas turbine first stage under hot-streak inlet conditions. Simulations were performed for two locations of hot-streak at turbine inlet with respect to the first stage vane, i.e. i) passage center and ii) blade center. The two kinds of inlet conditions have the same mass-averaged total temperature and total pressure. The passage center hot-streak total pressure and total temperature contours are obtained from the rig data published by Butler. Linear interpolation technique is used to move the hot-streak location from passage center to blade center. The ratio of highest temperature in hot-streak to free stream temperature is 2.0. Mixing plane (MP) and Non-linear harmonic (NLH) approaches are used to address the data transport across the rotor-stator station interface. The numerical solution is validated with the test data obtained from the published rig tests. NLH approach predicted the rotor blade surface temperature distributions close to rig data with a percentage deviation of 3%. The change in hot-streak circumferential position from blade center to passage center lead to decreased attenuation of hot-streak due to pronounced cross momentum transport of fluid across the viscous layers. Turbine flow with blade center hot-streak experiences transient periodic fluctuation of heat load on rotor surface. High temperature gradients are observed at turbine exit station with passage center hot-streak.

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Kandlikar, Satish G. "FLOW BOILING MAPS FOR WATER, R-22 AND R-134a IN THE SATURATED REGION." In International Heat Transfer Conference 9. Connecticut: Begellhouse, 1990. http://dx.doi.org/10.1615/ihtc9.30.

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Longo, J., J. Shao, M. lrvine, L. Gui, and F. Stern. "Unsteady PIV for regular head waves." In SNAME 26th American Towing Tank Conference. SNAME, 2001. http://dx.doi.org/10.5957/attc-2001-028.

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Phase-averaged results from a towing tank experiment of regular head waves are documented. Uniform flow, free surface elevation, and headwave flowfields are measured with a towed particle image velocimetry system in the Iowa Institute of Hydraulic Research towing tank of a two-dimensional, deep-water, longwavelength (A.=4.572 m), low wave steepness (Ak=0.025) progressive head wave. The towing speed is 1.53 m/s which corresponds to Fr=0.28 for a 3.048 m surface combatant which will be the focus of a future study for measuring the unsteady boundary layer and wake with the present measurement system. Uniform-flow measurements are conducted first to establish the resolution of the mean variables, levels of turbulence in three normal stresses and two Shear stress components, and uncertainties which are roughly 0.65% for the axial flow (U) and 0.5% for the transverse (V) and vertical components (W). Then, tests are conducted in headwaves at five elevations to map the orbital wave patterns. The data is phase-averaged and Fourier analyzed to determine the harmonic content in the measured headwave patterns. Results are compared with deep-water progressive wave theory to evaluate the qualities of the harmonic amplitudes and phases of the data. The 0th harmonic results for U, V, W=l, 0, 0 to within the resolution of the measurement system. The 1st harmonic of U,W are generally within 1- 2% of the theoretical harmonic amplitudes and demonstrate same exponential decay with increasing distance from the free surface as theory. Differences between experiment and theory of the 1st harmonic phase of U, W are observed in the results that are not fully understood but described with possible explanations. The data will be archived at the IIHR towing tank website at http://www.iihr.uiowa.edu/-towtank.

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F. Ponte Neto, Cosme, and Valiya M. Hamza. "Estimation of Errors in Spherical Harmonic Representation of Global Heat Flow." In Simpósio Brasileiro de Geofísica. Sociedade Brasileira de Geofísica, 2004. http://dx.doi.org/10.22564/1simbgf2004.022.

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F. Ponte Neto, Cosme, and Valiya M. Hamza. "Estimation Of Errors In Spherical Harmonic Representation Of Global Heat Flow." In I Simpósio Brasileiro de Geofísica. European Association of Geoscientists & Engineers, 2004. http://dx.doi.org/10.3997/2214-4609-pdb.216.i_sg_sbgf2004_ec_07.

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Spakovszky, Z. S., C. M. van Schalkwyk, H. J. Weigl, J. D. Paduano, K. L. Suder, and M. M. Bright. "Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part II — Circumferential Distortion." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-265.

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This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120° extent (DC(60) = 0.61) are reported in this paper. Part I (Spakovszky et al. (1998)) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multi-variable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well known incompressible Moore-Greitzer mode. Steady axisymmetric injection of 4% of the compressor mass flow resulted in a 6.2% reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9%. A more sophisticated robust controller allowed a reduction in stalling mass flow of 10.2% relative to steady injection, yielding a total reduction in stalling mass flow of 16.4%.

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