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Aerodynamic shape and drag scaling law of a flexible fibre in a flowing medium

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Theoretical & Applied Mechanics Letters 2023年第3期13卷 159-163页

作者： Bo-Hua Sun Xiao-Lin Guo School of Civil Engineering&Institute of Mechanics and Technology Xian University of Architecture and TechnologyXi’an 710055China

The study of a flexible body immersed in a flowing medium is one of the best way to find its aerodynamic shape.This Letter revisited the problem that was first studied by Alben et al.(Nature 420,479–481,2002).To determine the aerodynamic shape of the fibre,a simpler approach is proposed.A universal drag scaling law is obtained and the universality of the Alben-Shelley-Zhang scaling law is confirmed by using dimensional analysis.A complete Maple code is provided for finding aerodynamic shape of the fibre in the flowing medium.

关键词： Flexible fibre Flow medium Aerodynamic shape Drag scaling law

scaling law of resolved-scale isotropic turbulence and its application in large-eddy simulation

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Acta Mechanica Sinica 2014年第3期30卷 339-350页

作者： Le Fang Bo Li Li-Peng Lu cole Centrale de Pe'kin Beihang University The State Key Laboratory of Nonlinear Mechanics Chinese Academy of Science Laboratoire de M canique des Fluides et d’Acoustique Universit de Lyoncole centrale de Lyon69134 EcullyFrance School of Energy and Power Engineering Beihang University

Eddy-damping quasinormal Markovian （EDQNM） theory is employed to calculate the resolved-scale spectrum and transfer spectrum, based on which we investigate the resolved-scale scaling law. Results show that the scaling law of the resolved-scale turbulence, which is affected by several factors, is far from that of the full-scale turbulence and should be corrected. These results are then applied to an existing subgrid model to improve its performance. A series of simulations are performed to verify the necessity of a fixed scaling law in the subgrid modeling.

关键词： scaling law Large-eddy simulation CZZSmodel

scaling law of s-Wave Valence Proton Distributions

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Plasma Science and Technology 2012年第5期14卷 402-404页

作者：郭艳青 Department of Physics and Electronic Engineering Hanshan Normal University

Inthe framework of the single-particle potential model, the root-meamsquare radii of s-wave valence proton distributions for P and S isotopes have been systematically calculated. The scaling law of s-wave valence proton distributions is obtained by analyzing the relation between radii and separation energies. Necessary condition for the occurrence of 2sl/2-state proton halos is deduced from the scaling law. Quantitative condition derived from this work can to some extent serve as reference for proton halo search.

关键词： scaling law s-wave proton halo single-particle potential model

scaling law of single ion–atom impact ionization cross sections of noble gases from He to Xe at strong perturbative energies

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Chinese Physics B 2015年第6期24卷 296-300页

作者：任屏源邹贤容邵剑雄王诗尧周满周旺杨爱香闫鹏勋陈熙萌 School of Physical Science and Technology Lanzhou University School of Nuclear Science and Technology Lanzhou University

We extend our previous work of a classical over-barrier ionization （COBI） model to calculate the single ionization cross sections of noble gases ranging from He to Xe at strong perturbative energies. The calculation results are in good agreement with extensive experimental data. The scaling law of single ion-atom impact ionization cross sections of noble gases on projectile charge q and energy E, also on target ionization energy I is drawn from the model.

关键词： scaling law single ionization noble gases strong perturbation

A scaling law of high-order harmonic generation

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Chinese Physics B 2012年第2期21卷 351-356页

作者：吴艳叶会亮邵初寅张敬涛 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Changshu Institute of Technology Changshu 215500China

Using a nonperturbative quantum electrodynamics theory of high-order harmonic generation （HHG）, a scaling law of HHG is established. The scaling law states that when the atomic binding energy Eb, the wavelength ）, and the intensity I of the laser field change simultaneously to kEb, λ/k, and k3I, respectively. The characteristics of the HHG spectrum remain unchanged, while the harmonic yield is enhanced k3 times. That HHG obeys the same scaling law with above-threshold ionization is a solid proof of the fact that the two physical processes have similar physical mechanisms. The variation of integrated harmonic yields is also discussed.

关键词： high-order harmonic generation scaling law harmonic yield nonperturbative quantumelectrodynamics

Hydrodynamic scaling law in undulatory braking locomotion

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Science China(Physics,Mechanics & Astronomy) 2021年第7期64卷 108-119页

作者： QiangQiang Hu YongLiang Yu Lab of Biomechanics for Animal Locomotion University of Chinese Academy of SciencesBeijing100049China

Flow over a fish-like airfoil is numerically investigated to elaborate the hydrodynamics of the undulatory braking locomotion for an elongated eel-like body or long-based fin. For undulation with low frequency, we find that boundary layer separation occurs in a parameter region with wakes in which two vortex pairs are formed per undulatory period. The physical mechanism of separation is governed by the slip(the ratio of swimming-to-body-wave speed), and the critical value of the slip in an inertial flow regime is approximately 4/3 rather than 1, which is independent of steepness(or amplitude). The relationship between pressure drag and relative velocity(between phase speed and free stream velocity) changes from linear to quadratic, corresponding to two different flow structures;this happens due to boundary layer separation, and the piecewise scaling relationship between pressure drag and relative velocity is explicitly clarified. Considering the viscosity effects, the separation criterion and the scaling relationship in the case of an undulatory brake are both synthetically modified using the Reynolds number, with all the required parameters clearly expressed. The results of this study provide physical insight into understanding the flow structures and hydrodynamics of the undulatory braking locomotion, which has instructional significance to brake design.

关键词： fish swimming undulatory braking scaling law boundary layer separation resistance enhancement

Studies on convergence and scaling law of Thomson backscattering spectra in strong fields

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Chinese Physics B 2017年第12期26卷 237-241页

作者：谢含章蒋纯谢柏松 College of Applied Science Beijing University of Technology Beijing 100124 China College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China Beijing Radiation Center Beijing 100875 China

With the saddle point analysis method for the Bessel function structure and property, the convergence problem and the scaling laws of Thomson backscattering spectra are solved and studied in both cases that are for the plane wave laser field without and with applied external constant magnetic field. Some unclear points appeared in previous work are clarified. The extension of the method to a general situation for the laser field with an arbitrary polarization is discussed. We also make a simple analysis and discussion about the optimal spectra dependence of field parameters and its implication to practical applications.

关键词： radiation by moving charges Thomson scattering spectra frequency conversion and harmonic generation scaling law

RELATION BETWEEN COHERENT STRUCTURE AND scaling law IN RAYLEIGH-BENARD CONVECTION BASED ON WAVELET TRANSFORMATION

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Journal of Hydrodynamics 2004年第4期16卷 436-441页

作者： FUQiang JIANGMin XIAKe-qing SchoolofScience P.L.A.UniversityofScienceandTechnologyNanjing211101China Departmentofphysics TheChineseUniversityofHongKongHongKongChina SchoolofScience P.L.A.UniversityofScienceandTechnologyNanjing211101China Departmentofphysics TheChineseUniversityofHongKongHongKongChina

In this paper, the Extended Self Similarity (ESS) was used to study thescaling exponent ξ(q) of temperature data in the Reyleigh-Benard convection and its variation withexperimental measuring locations. The results show that ξ(q) varies with locations and agrees wellwith experimental data. And then the wavelet transformation is used to extract the coherentstructure, by means of the definition of a called non-coherent signal. we can understand theinfluence of coherent structure on ξ(q) and the relations between large scale vortex motions andsmall ones.

关键词： scaling law coherent structure wavelet transformation rayleigh-benardconvection

Novel scaling law for estimating propeller tip vortex cavitation noise from model experiment

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Journal of Hydrodynamics 2017年第6期29卷 962-971页

作者： Jisoo Park Woojae Seong Department of Naval Architecture and Ocean Engineering Seoul National UniversitySeoulKorea

The tip vortex cavitation（TVC） noise of marine propellers is of interest due to the environmental impacts from commercial ships as well as for the survivability of naval ships. Due to complicated flow and noise field around a marine propeller, a theoretical approach to the estimation of TVC noise is practically unrealizable. Thus, estimation of prototype TVC noise level is realized through extrapolation of the model TVC noise level measured in a cavitation tunnel. In this study, for the prediction of prototype TVC noise level from a model test, a novel scaling law reflecting the physical basis of TVC is derived from the Rayleigh-Plesset equation, the Rankine vortex model, the lifting surface theory, and other physical assumptions. Model and prototype noise data were provided by Samsung Heavy Industries（SHI） for verification. In applying the novel scaling law, similitude of the spectra of nuclei is applied to assume the same nuclei distribution in the tip vortex line of the model and the prototype. It was found that the prototype TVC noise level predicted by the novel scaling law has better agreement with the prototype TVC noise measurement than the prototype TVC noise level predicted by the modified ITTC noise estimation rule.

关键词： Tip vortex cavitation underwater radiated noise scaling law