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Lloyd H. Back

Bio: Lloyd H. Back is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Boundary layer & Coronary flow reserve. The author has an hindex of 27, co-authored 150 publications receiving 2312 citations. Previous affiliations of Lloyd H. Back include Jet Propulsion Laboratory & Drexel University.


Papers
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TL;DR: In this paper, internal flow measurements in transonic region of supersonic nozzle with small throat radius of curvature compared with prediction data were used to estimate the internal flow of a supersonically-charged supersonica nozzle.
Abstract: Internal flow measurements in transonic region of supersonic nozzle with small throat radius of curvature compared with prediction data

141 citations

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TL;DR: Convective heat transfer for turbulent boundary layer flow through cooled convergent-divergent nozzle was investigated in this paper, where the authors used a cooling convergent divergent nozzle.

93 citations

Journal ArticleDOI
TL;DR: In this paper, measured and predicted flows through conical supersonic nozzles compared, emphasizing transonic region of transonic regions were measured and forecasted flows through Conical Supersonic Nozzles.
Abstract: Measured and predicted flows through conical supersonic nozzles compared, emphasizing transonic region

85 citations

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TL;DR: Analytical flow modeling and in vitro experimental evidence, coupled with angiographic data on the dimensions and shape of stenotic vessel segments before and after angioplasty, indicated significant flow blockage effects with the catheter present.
Abstract: Quantitative methods to measure the hemodynamic consequences of various endovascular interventions including balloon angioplasty are limited. Catheters measuring translesional pressure drops during balloon angioplasty procedures can cause flow blockage and thus inaccurate estimates of pre- and post-intervention flow rates. The purpose of this investigation was to examine the influence of the presence and size of an angioplasty catheter on measured mean pressure gradients across human coronary artery stenoses. Analytical flow modeling and in vitro experimental evidence, coupled with angiographic data on the dimensions and shape of stenotic vessel segments before and after angioplasty, indicated significant flow blockage effects with the catheter present.

82 citations

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TL;DR: In this article, the influence of the presence and size of the catheter on the measurement of mean pressure drop and, thus, flow resistance in coronary vessels was examined, and analytical flow modeling coupled with in vitro experimental evidence was used to estimate mean flow resistance increases due to the presence of a catheter in a proximal vessel for concentric and eccentric catheter configurations.

80 citations


Cited by
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TL;DR: The pulsatile hemodynamics of the left coronary artery bifurcation was numerically simulated using the spectral element method for realistic in vivo anatomic and physiologic conditions and found the velocity profiles were found to be skewed.
Abstract: The localization of atherosclerosis in the coronary arteries may be governed by local hemodynamic features. In this study, the pulsatile hemodynamics of the left coronary artery bifurcation was numerically simulated using the spectral element method for realistic in vivo anatomic and physiologic conditions. The velocity profiles were found to be skewed in both the left anterior descending and the circumflex coronary arteries. Velocity skewing arose from the bifurcation as well as from the curvature of the artery over the myocardial surface. Arterial wall shear stress was significantly lower in the bifurcation region, including the side walls. The greatest oscillatory behavior was localized to the outer wall of the circumflex artery. The time-averaged mean wall shear stress varied from about 3 to 98 dynes/cm 2 in the left coronary artery system. The highly localized distribution of low and oscillatory shear stress along the walls strongly correlates with the focal locations of atheroma in the human left coronary artery.

622 citations

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TL;DR: In this article, the advantages of the detonation cycle over the constant pressure combustion cycle, typical of conventional propulsion engines, are discussed, and the impact of the early work on these recent developments and some of the outstanding issues are also discussed.
Abstract: Applications of detonations to propulsion are reviewed. First, the advantages of the detonation cycle over the constant pressure combustion cycle, typical of conventional propulsion engines, are discussed. Then the early studies of standing normal detonations, intermittent (or pulsed) detonations, rotating detonations, and oblique shock-induced detonations are reviewed. This is followed by a brief discussion of detonation thrusters, lasersupported detonations and oblique detonation wave engines. Finally, a more detailed review of research during the past decade on ram accelerators and pulsed detonation engines is presented. The impact of the early work on these recent developments and some of the outstanding issues are also discussed.

600 citations

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TL;DR: A new multidomain spectral collocation method that uses a staggered grid for the solution of compressible flow problems that is conservative, free-stream preserving, and exponentially accurate.

455 citations

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TL;DR: In this paper, an assessment of the challenges of understanding basic physics through utilizing rotating detonations in aerospace platforms is provided, ranging from understanding the basic physics of the system to its feasibility.
Abstract: Rotating detonation engines (RDEs), also known as continuous detonation engines, have gained much worldwide interest lately. Such engines have huge potential benefits arising from their simplicity of design and manufacture, lack of moving parts, high thermodynamic efficiency and high rate of energy conversion that may be even more superior than pulse detonation engines, themselves the subject of great interest. However, due to the novelty of the concept, substantial work remains to demonstrate feasibility and bring the RDE to reality. An assessment of the challenges, ranging from understanding basic physics through utilizing rotating detonations in aerospace platforms, is provided.

451 citations