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Time-domain measurement of Auger electron dynamics in xenon atoms after giant resonant photoionization
Authors:
Mahmudul Hasan,
Jingsong Gao,
Hao Liang,
Yiming Yuan,
Zach Eisenhutt,
Ming-Shian Tsai,
Ming-Chang Chen,
Hans Jakob Wörner,
Artem Rudenko,
Meng Han
Abstract:
Time-resolved measurement of Auger-Meitner (AM) decay [Nature 419, 803 (2002)] marked a milestone in the development of attosecond science. To date, the time constants for the AM decay processes obtained from the time-domain experiments were found to be consistent with the values deduced from conventional energy-domain measurements. One of the main factors limiting the temporal resolution of these…
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Time-resolved measurement of Auger-Meitner (AM) decay [Nature 419, 803 (2002)] marked a milestone in the development of attosecond science. To date, the time constants for the AM decay processes obtained from the time-domain experiments were found to be consistent with the values deduced from conventional energy-domain measurements. One of the main factors limiting the temporal resolution of these studies is the unlocked carrier-envelope-phase (CEP) of the laser pulses used to probe the electronic dynamics triggered by inner-shell photoabsorption. In this work, we report time-resolved inner-shell electron spectroscopy of xenon and krypton using attosecond soft X-ray (atto-SXR) pulses centered at 130 eV in combination with CEP-stabilized few-cycle Yb laser pulses. We observed that the N$_{4,5}$OO Auger electrons from xenon exhibit a clear streaking pattern, but with an unexpected time shift of $\sim$ 1.32 fs relative to the 4$d$ photoelectrons. Furthermore, the energy-integrated yield of streaked Auger electrons from xenon exhibits a pronounced minimum at a pump-probe time delay of 4 fs. Neither of these observations can be explained by current streaking theories and both are inconsistent with lifetimes inferred from energy-domain measurements. The M$_{4,5}$NN Auger electrons from krypton partly overlap in energy with the 3$d$ inner-shell photoelectrons and do not show these anomalous features. This study offers new insights into the inner-shell electron dynamics of heavy atoms in the giant dipole resonance region, laying the groundwork for attosecond soft X-ray spectroscopy of molecular systems containing iodine or bromine atoms.
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Submitted 22 December, 2025;
originally announced December 2025.
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Strong-Field Photoelectron Interferometry with Near-Single-Cycle Yb Lasers
Authors:
Mahmudul Hasan,
Phi-Hung Tran,
Jingsong Gao,
Van-Hung Hoang,
Ming-Shian Tsai,
Ming-Chang Chen,
Uwe Thumm,
Charles Lewis Cocke,
Chii-Dong Lin,
Anh-Thu Le,
and Meng Han
Abstract:
The concept of using photoelectron interferometry in short laser fields to probe electron dynamics and target structures was introduced more than two decades ago. However, the quality of experimental data has remained insufficient for quantitative analysis, largely due to the instability of few-cycle Ti:Sa laser pulses, the current workhorse of short pulses. Here, we report the first systematic st…
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The concept of using photoelectron interferometry in short laser fields to probe electron dynamics and target structures was introduced more than two decades ago. However, the quality of experimental data has remained insufficient for quantitative analysis, largely due to the instability of few-cycle Ti:Sa laser pulses, the current workhorse of short pulses. Here, we report the first systematic strong-field ionization experiments performed with industrial-grade, carrier-envelope-phase (CEP) stabilized, near-single-cycle Yb lasers. By measuring photoelectron momentum distributions in the direct-ionization regime, we show that single-cycle cosine-shaped pulses can separate and enhance both spider-leg and fishbone holographic structures. The spider-leg structure enables extraction of the electron scattering phase from the Ar atomic potential-information typically accessible only through attosecond metrology, while the fishbone structure reveals the orbital-parity contrast between Ar atoms and nitrogen molecules. Our measurements are quantitatively reproduced by both semiclassical Herman-Kluk-propagator and \textit{ab initio} simulations, paving the way for precision studies of electron-molecule scattering with widely accessible industrial-grade lasers.
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Submitted 2 September, 2025; v1 submitted 1 September, 2025;
originally announced September 2025.
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Bright 25-attosecond light pulses reach the one atomic unit of time
Authors:
Jingsong Gao,
Mahmudul Hasan,
Hao Liang,
Ming-Shian Tsai,
Yiming Yuan,
Zach Eisenhutt,
Christoph H. Keitel,
Chii-Dong Lin,
Yunquan Liu,
Ming-Chang Chen,
Meng Han
Abstract:
Generating ever-shorter and brighter light pulses has long been a central pursuit in ultrafast science, as it benchmarks our ability to create and manipulate the coherence on the intrinsic timescale of sub-atomic electron motion. The current state-of-the-art in attosecond pulse generation reaches durations of 40-50 attoseconds (1 as = $10^{-18}$ seconds), produced via high-order harmonic generatio…
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Generating ever-shorter and brighter light pulses has long been a central pursuit in ultrafast science, as it benchmarks our ability to create and manipulate the coherence on the intrinsic timescale of sub-atomic electron motion. The current state-of-the-art in attosecond pulse generation reaches durations of 40-50 attoseconds (1 as = $10^{-18}$ seconds), produced via high-order harmonic generation (HHG) driven by secondary mid-infrared light sources. However, these sources often suffer from low stability and poor HHG conversion efficiency. In this work, we demonstrate the generation of 25$\pm$2 attosecond light pulses, a new world record for the shortest light pulse, driven by a post-compressed, industrial-grade Yb-based laser system. The resulting high-harmonic spectrum spans photon energies from 50 eV to 320 eV, covering the carbon K-edge, with a calibrated photon flux exceeding $10^{12}$ photons per second, approximately three orders of magnitude higher than previous studies. The pulse duration was characterized using an angle-resolved photoelectron streaking camera on helium atoms and systematically optimized through the use of dielectric filters of varying thicknesses to compensate the attochirp. Our study reaches the threshold of one atomic unit of time (24.2 attoseconds), the boundary between atomic and ionic physics, opening the door to resolving exciting ionic quantum dynamics with tabletop lasers.
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Submitted 20 August, 2025;
originally announced August 2025.
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Design, Construction, and Testing of the APOLLO ATCA Blades for Use at the HL-LHC
Authors:
Alp Akpinar,
Aymeric Blaizot,
Serhii Cholak,
Gianfranco de Castro,
Zeynep Demiragli,
Alec Duquette,
Jonathan Richard Fulcher,
Dan Gastler,
Kristian Hahn,
Eric Shearer Hazen,
Si Hyun Jeon,
Peace Kotamnives,
Alexander Madorsky,
David Monk,
Sheena Noorudhin,
Michael Oshiro,
James Rohlf,
Charles Ralph Strohman,
Emily Minyun Tsai,
Peter Wittich,
Siqi Yuan,
Rui Zou
Abstract:
The Apollo Advanced Telecommunications Computing Architecture (ATCA) platform is an open-source design consisting of a generic "Service Module" (SM) and a customizable "Command Module" (CM), allowing for cost-effective use in applications such as the readout of the inner tracker and the Level-1 track trigger for the CMS Phase-II upgrade at the HL-LHC. The SM integrates an intelligent IPMC, robust…
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The Apollo Advanced Telecommunications Computing Architecture (ATCA) platform is an open-source design consisting of a generic "Service Module" (SM) and a customizable "Command Module" (CM), allowing for cost-effective use in applications such as the readout of the inner tracker and the Level-1 track trigger for the CMS Phase-II upgrade at the HL-LHC. The SM integrates an intelligent IPMC, robust power entry and conditioning systems, a powerful system-on-module computer, and flexible clock and communication infrastructure. The CM is designed around two Xilinx Ultrascale+ FPGAs and high-density, high-bandwidth optical transceivers capable of 25 Gb/s. Crates of Apollo blades are currently being tested at Boston University, Cornell University, and CERN.
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Submitted 21 March, 2025; v1 submitted 7 January, 2025;
originally announced January 2025.
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Filamentation-Assisted Isolated Attosecond Pulse Generation
Authors:
Yu-En Chien,
Marina Fernández-Galán,
Ming-Shian Tsai,
An-Yuan Liang,
Enrique Conejero-Jarque,
Javier Serrano,
Julio San Román,
Carlos Hernández-García,
Ming-Chang Chen
Abstract:
Isolated attosecond pulses (IAPs) generated by few-cycle femtosecond lasers are essential for capturing ultrafast dynamics in atoms, molecules, and solids. Nonetheless, the advancement of attosecond science critically depends on achieving stable, high-temporal-contrast IAPs. Our study reveals a universal scenario in which self-compression of the infrared driver in high harmonic generation in exten…
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Isolated attosecond pulses (IAPs) generated by few-cycle femtosecond lasers are essential for capturing ultrafast dynamics in atoms, molecules, and solids. Nonetheless, the advancement of attosecond science critically depends on achieving stable, high-temporal-contrast IAPs. Our study reveals a universal scenario in which self-compression of the infrared driver in high harmonic generation in extended gas media leads to high-contrast high-frequency IAP generation. Our experimental and theoretical results reveal that filamentation in a semi-infinite gas cell not only shapes the infrared driving pulse spatially and temporally, but also creates a stable propagation region where high harmonic generation is phase-matched, leading to the production of bright IAPs. In an argon-filled gas cell, filamentation notably reduces the pulse duration of Yb-based 1030 nm pulses from 4.7 fs to 3.5 fs, while simultaneously generating high-contrast 200-attosecond IAPs at 70 eV. We demonstrate the universality of filamentation-assisted IAP generation, showing that post-compressed Yb-based laser filaments in neon and helium yield even shorter IAPs: 69-attoseconds at 100 eV, and 65-attoseconds IAPs at 135 eV, respectively. This spatiotemporal reshaping of few-cycle pulses through filamentation possesses immediate impacts on both post-compression techniques and attosecond-based technologies.
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Submitted 9 December, 2024;
originally announced December 2024.
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Hearing carrier-envelope offset frequency and phase in air with a microphone
Authors:
Meng Han,
Ming-Chang Chen,
Ming-Shian Tsai,
Hao Liang
Abstract:
Attosecond science and frequency metrology rely on the precise measurement and control of the laser pulse waveform, a feat traditionally achieved using optoelectronic techniques. In this study, we conducted a laser-induced acoustic experiment in air ionized by carrier-envelope phase (CEP)-stabilized sub-4 femtosecond pulses. Our results reveal that the acoustic signal exhibits CEP dependence in fe…
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Attosecond science and frequency metrology rely on the precise measurement and control of the laser pulse waveform, a feat traditionally achieved using optoelectronic techniques. In this study, we conducted a laser-induced acoustic experiment in air ionized by carrier-envelope phase (CEP)-stabilized sub-4 femtosecond pulses. Our results reveal that the acoustic signal exhibits CEP dependence in few-cycle pulses, primarily through amplitude modulation from laser-driven ionization. This novel optoacoustic phenomenon enables not only the measurement of the carrier-envelope offset frequency but also the direct characterization of the waveform of optical pulses through a microphone. Our study highlights the potential of laser-induced acoustic waves for advancing frequency metrology and ultrafast science.
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Submitted 29 March, 2025; v1 submitted 12 November, 2024;
originally announced November 2024.
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Superior visible photoelectric response with Au/Cu2NiSnS4 core-shell nanocrystals
Authors:
Anima Ghosh,
Shyam Narayan Singh Yadav,
Ming-Hsiu Tsai,
Abhishek Dubey,
Shangjr Gwo,
Chih-Ting Lin,
Ta- Jen Yen
Abstract:
The incorporation of plasmonic metal nanostructures into semiconducting chalcogenides, in the form of core-shell structures, represents a promising approach to boosting the performance of photodetectors. In this study, we combined Au nanoparticles with newly developed copper-based chalcogenides Cu2NiSnS4 (Au/CNTS), to achieve an ultrahigh optoelectronic response in the visible regime. The high-qua…
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The incorporation of plasmonic metal nanostructures into semiconducting chalcogenides, in the form of core-shell structures, represents a promising approach to boosting the performance of photodetectors. In this study, we combined Au nanoparticles with newly developed copper-based chalcogenides Cu2NiSnS4 (Au/CNTS), to achieve an ultrahigh optoelectronic response in the visible regime. The high-quality Au/CNTS core-shell structure was synthesized by developing a unique colloidal hot-injection method, which allowed excellent control over sizes, shapes, and elemental compositions. The fabricated Au/CNTS hybrid core-shell structure exhibited enhanced optical absorption, carrier extraction efficiency, and improved photo-sensing performance, owing to the plasmonic-induced resonance energy transfer effect of the Au core. This effect led to a significant increase in carrier density between the Au core and CNTS shell. These values outperformed a CNTS-based gate-free visible photodetector.
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Submitted 29 August, 2023; v1 submitted 6 August, 2023;
originally announced August 2023.
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General Mechanism of Evolution Shared by Proteins and Words
Authors:
Li-Min Wang,
Hsing-Yi Lai,
Sun-Ting Tsai,
Chen Siang Ng,
Kevin Sheng-Kai Ma,
Shan-Jyun Wu,
Meng-Xue Tsai,
Yi-Ching Su,
Daw-Wei Wang,
Tzay-Ming Hong
Abstract:
Complex systems, such as life and languages, are governed by principles of evolution. The analogy and comparison between biology and linguistics\cite{alphafold2, RoseTTAFold, lang_virus, cell language, faculty1, language of gene, Protein linguistics, dictionary, Grammar of pro_dom, complexity, genomics_nlp, InterPro, language modeling, Protein language modeling} provide a computational foundation…
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Complex systems, such as life and languages, are governed by principles of evolution. The analogy and comparison between biology and linguistics\cite{alphafold2, RoseTTAFold, lang_virus, cell language, faculty1, language of gene, Protein linguistics, dictionary, Grammar of pro_dom, complexity, genomics_nlp, InterPro, language modeling, Protein language modeling} provide a computational foundation for characterizing and analyzing protein sequences, human corpora, and their evolution. However, no general mathematical formula has been proposed so far to illuminate the origin of quantitative hallmarks shared by life and language. Here we show several new statistical relationships shared by proteins and words, which inspire us to establish a general mechanism of evolution with explicit formulations that can incorporate both old and new characteristics. We found natural selection can be quantified via the entropic formulation by the principle of least effort to determine the sequence variation that survives in evolution. Besides, the origin of power law behavior and how changes in the environment stimulate the emergence of new proteins and words can also be explained via the introduction of function connection network. Our results demonstrate not only the correspondence between genetics and linguistics over their different hierarchies but also new fundamental physical properties for the evolution of complex adaptive systems. We anticipate our statistical tests can function as quantitative criteria to examine whether an evolution theory of sequence is consistent with the regularity of real data. In the meantime, their correspondence broadens the bridge to exchange existing knowledge, spurs new interpretations, and opens Pandora's box to release several potentially revolutionary challenges. For example, does linguistic arbitrariness conflict with the dogma that structure determines function?
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Submitted 17 March, 2026; v1 submitted 28 December, 2020;
originally announced December 2020.
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Spin-orbit-torque MRAM: from uniaxial to unidirectional switching
Authors:
Ming-Han Tsai,
Po-Hung Lin,
Kuo-Feng Huang,
Hsiu-Hau Lin,
Chih-Huang Lai
Abstract:
With ultra-fast writing capacity and high reliability, the spin-orbit torque is regarded as a promising alternative to fabricate next-generation magnetic random access memory. However, the three-terminal setup can be challenging when scaling down the cell size. In particular, the thermal stability is an important issue. Here we demonstrate that the current-pulse-induced perpendicular exchange bias…
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With ultra-fast writing capacity and high reliability, the spin-orbit torque is regarded as a promising alternative to fabricate next-generation magnetic random access memory. However, the three-terminal setup can be challenging when scaling down the cell size. In particular, the thermal stability is an important issue. Here we demonstrate that the current-pulse-induced perpendicular exchange bias can significantly relieve the concern of thermal stability. The switching of the exchange bias direction is induced by the spin-orbit torque when passing current pulses through the Pt/Co system with an inserted IrMn antiferromagnetic layer. Manipulating the current-pulse-induced exchange bias, spin-orbit-torque switching at zero field between states with unidirectional anisotropy is achieved and the thermal agitation of the magnetic moment is strongly suppressed. The spin-orbit torque mechanism provides an innovative method to generate and to control the exchange bias by electrical means, which enables us to realize the new switching mechanism of highly stable perpendicular memory cells.
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Submitted 6 June, 2017;
originally announced June 2017.
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Power-law ansatz in complex systems: excessive loss of information
Authors:
Sun-Ting Tsai,
Chin-De Chang,
Ching-Hao Chang,
Meng-Xue Tsai,
Nan-Jung Hsu,
Tzay-Ming Hong
Abstract:
The ubiquity of power-law relations in empirical data displays physicists' love of simple laws and uncovering common causes among seemingly unrelated phenomena. However, many reported power laws lack statistical support and mechanistic backings, not to mention discrepancies with real data are often explained away as corrections due to finite size or other variables. We propose a simple experiment…
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The ubiquity of power-law relations in empirical data displays physicists' love of simple laws and uncovering common causes among seemingly unrelated phenomena. However, many reported power laws lack statistical support and mechanistic backings, not to mention discrepancies with real data are often explained away as corrections due to finite size or other variables. We propose a simple experiment and rigorous statistical procedures to look into these issues. Making use of the fact that the occurrence rate and pulse intensity of crumple sound obey power law with an exponent that varies with material, we simulate a complex system with two driving mechanisms by crumpling two different sheets together. The probability function of crumple sound is found to transit from two power-law terms to a {\it bona fide} power law as compaction increases. In addition to showing the vicinity of these two distributions in the phase space, this observation nicely demonstrates the effect of interactions to bring about a subtle change in macroscopic behavior and more information may be retrieved if the data are subject to sorting. Our analyses are based on the Akaike information criterion that is a direct measurement of information loss and emphasizes the need to strike a balance between model simplicity and goodness of fit. As a show of force, the Akaike information criterion also found the Gutenberg-Richter law for earthquakes and the scale-free model for brain functional network, 2-dimensional sand pile, and solar flare intensity to suffer excessive loss of information. They resemble more the crumpled-together ball at low compactions in that there appear to be two driving mechanisms that take turns occurring.
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Submitted 4 January, 2016; v1 submitted 8 May, 2015;
originally announced May 2015.
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Nonlinear Raman Shift Induced by Exciton-to-Trion Transformation in Suspended Trilayer MoS2
Authors:
Hossein Taghinejad,
Mohammad Taghinejad,
Alexey Tarasov,
Meng-Yen Tsai,
Amir H. Hosseinnia,
Philip M. Campbell,
Ali A. Eftekhar,
Eric M. Vogel,
Ali Adibi
Abstract:
Layered two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have recently attracted remarkable attention because of their unique physical properties. Here, we use photoluminescence (PL) and Raman spectroscopy to study the formation of the so- called trions in a synthesized freestanding trilayer MoS2. A trion is a charged quasi-particle formed by adding one electron or hole to a…
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Layered two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have recently attracted remarkable attention because of their unique physical properties. Here, we use photoluminescence (PL) and Raman spectroscopy to study the formation of the so- called trions in a synthesized freestanding trilayer MoS2. A trion is a charged quasi-particle formed by adding one electron or hole to a neutral exciton (a bound electron-hole pair). We demonstrate accurate control over the transformation of excitons to trions by tuning the power of the optical pump (laser). Increasing the power of the excitation laser beyond a certain threshold (~ 4 mW) allows modulation of trion-to-exciton PL intensity ratio as well as the spectral linewidth of both trions and excitons. Via a systematic and complementary Raman analysis we disclose a strong coupling between laser induced exciton-to-trion transformation and the characteristic phononic vibrations of MoS2. The onset of such an optical transformation corresponds to the onset of a previously unknown nonlinear Raman shift of the in-plane (E12g) and out-of-plane (A1g) vibrational modes. This coupling directly affects the well-known linear red-shift of the A1g and E12g vibrations due to heating at low laser powers, and changes it to a nonlinear and non-monotonic dependence with a blue-shift in the high laser power regime. Local reduction of the electron density upon exciton-to-trion transformation is found to be the underlying mechanism for the blue-shift at high laser powers. Our findings enrich our knowledge about the strong coupling of photonic and phononic properties in 2D semiconductors, and enable reliable interpretation of PL and Raman spectra in the high laser power regimes.
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Submitted 2 February, 2015;
originally announced February 2015.
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Photon transport enhanced by transverse Anderson localization in disordered superlattices
Authors:
Pin-Chun Hsieh,
Chung-Jen Chung,
James McMillan,
Min-An Tsai,
Ming Lu,
Nicolae Panoiu,
Chee Wei Wong
Abstract:
One of the daunting challenges in optical physics is to accurately control the flow of light at the subwavelength scale, by patterning the optical medium one can design anisotropic media. The light transport can also be significantly affected by Anderson localization, namely the wave localization in a disordered medium, a ubiquitous phenomenon in wave physics. Here we report the photon transport a…
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One of the daunting challenges in optical physics is to accurately control the flow of light at the subwavelength scale, by patterning the optical medium one can design anisotropic media. The light transport can also be significantly affected by Anderson localization, namely the wave localization in a disordered medium, a ubiquitous phenomenon in wave physics. Here we report the photon transport and collimation enhanced by transverse Anderson localization in chip-scale dispersion engineered anisotropic media. We demonstrate a new type of anisotropic photonic structure in which diffraction is nearly completely arrested by cascaded resonant tunneling through transverse guided resonances. By perturbing the shape of more than 4,000 scatterers in these superlattices we add structural disordered in a controlled manner and uncover the mechanism of disorder-induced transverse localization at the chip-scale. Arrested spatial divergence is captured in the power-law scaling, along with exponential asymmetric mode profiles and enhanced collimation bandwidth for increasing disorder. With increasing disorder, we observe the crossover from cascaded guided resonances into the transverse localization regime, beyond the ballistic and diffusive transport of photons.
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Submitted 12 December, 2014;
originally announced December 2014.
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Assessment of density functional approximations for the hemibonded structure of water dimer radical cation
Authors:
Piin-Ruey Pan,
You-Sheng Lin,
Ming-Kang Tsai,
Jer-Lai Kuo,
Jeng-Da Chai
Abstract:
Due to the severe self-interaction errors associated with some density functional approximations, conventional density functionals often fail to dissociate the hemibonded structure of water dimer radical cation (H2O)2+ into the correct fragments: H2O and H2O+. Consequently, the binding energy of the hemibonded structure (H2O)2+ is not well-defined. For a comprehensive comparison of different funct…
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Due to the severe self-interaction errors associated with some density functional approximations, conventional density functionals often fail to dissociate the hemibonded structure of water dimer radical cation (H2O)2+ into the correct fragments: H2O and H2O+. Consequently, the binding energy of the hemibonded structure (H2O)2+ is not well-defined. For a comprehensive comparison of different functionals for this system, we propose three criteria: (i) The binding energies, (ii) the relative energies between the conformers of the water dimer radical cation, and (iii) the dissociation curves predicted by different functionals. The long-range corrected (LC) double-hybrid functional, omegaB97X-2(LP) [J.-D. Chai and M. Head-Gordon, J. Chem. Phys., 2009, 131, 174105.], is shown to perform reasonably well based on these three criteria. Reasons that LC hybrid functionals generally work better than conventional density functionals for hemibonded systems are also explained in this work.
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Submitted 6 April, 2012;
originally announced April 2012.
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Simulations of Detonation Wave Propagation in Rectangular Ducts Using a Three-Dimensional WENO Scheme
Authors:
Hua-Shu Dou,
Her Mann Tsai,
Boo Cheong Khoo,
Jianxian Qiu
Abstract:
This paper reports high resolution simulations using a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third order TVD Runge-Kutta time stepping method to examine the features of detonation front and physics in square ducts. The simulations suggest that two and three-dimensional detonation wave front formations are greatly enhanced by the presence of transverse waves. The mot…
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This paper reports high resolution simulations using a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third order TVD Runge-Kutta time stepping method to examine the features of detonation front and physics in square ducts. The simulations suggest that two and three-dimensional detonation wave front formations are greatly enhanced by the presence of transverse waves. The motion of transverse waves generates triple points (zones of high pressure and large velocity coupled together), which cause the detonation front to become locally overdriven and thus form "hot spots". The transversal motion of these hot spots maintains the detonation to continuously occur along the whole front in two and three-dimensions. The present simulations indicate that the influence of the transverse waves on detonation is more profound in three dimensions and the pattern of quasi-steady detonation fronts also depends on the duct size. For a narrow duct (4LX4L where L is the half reaction length), the detonation front displays a distinctive "spinning" motion about the axial direction with a well-defined period. For a wider duct (20LX20L), the detonation front exhibits a "rectangular mode" periodically, with the front displaying "convex" and "concave" shapes one following the other and the transverse waves on the four walls being partly out-of-phase with each other.
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Submitted 7 June, 2010;
originally announced June 2010.
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Determining the Critical Condition for Flow Transition in a Full-Developed Annulus Flow
Authors:
Hua-Shu Dou,
Boo Cheong Khoo,
Her Mann Tsai
Abstract:
Axial flow in an annulus between two concentric cylinders is commonly seen in various flow devices used in chemical processing industries and petroleum science and engineering. The flow state in the annulus strongly influences the performance of fluid transportation in the devices. Therefore, the determination of flow state which is laminar flow or turbulent flow is an important task to predict th…
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Axial flow in an annulus between two concentric cylinders is commonly seen in various flow devices used in chemical processing industries and petroleum science and engineering. The flow state in the annulus strongly influences the performance of fluid transportation in the devices. Therefore, the determination of flow state which is laminar flow or turbulent flow is an important task to predict the performance of the flow devices. In previous works, we have proposed an energy gradient method for studying the flow instability and turbulent transition. In this method, it is shown that the flow instability and turbulent transition in wall bounded shear flows depend on the relative magnitude of the gradient of the total mechanical energy in transverse direction and the rate of loss of the total mechanical energy along the streamwise direction for a given imposed disturbance. For pipe and plane Poiseuille flows, it has been demonstrated that the transition to turbulence for these wall bounded parallel flows occurs at a consistent value of the energy gradient parameter (Kmax). In present study, the critical condition for turbulent transition in annulus flow is calculated with the energy gradient method for various radius ratios. The critical flow rate and critical Reynolds number are given for various radius ratios. Then, the analytical results are compared with the experiments in the literature. Finally, the implication of the result is discussed in terms of the drag reduction and mixing as well as heat transfer in practical industrial applications of various fluid delivery devices.
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Submitted 7 June, 2010; v1 submitted 27 April, 2005;
originally announced April 2005.