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DNS in evolution of vorticity and sign relationship in wake transition of a circular cylinder:(pure)mode A

Acta mechanica Sinica 2019年第6期35卷 1131-1149页

作者： l.m.lin Z.R.Tan Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Navigation Wuhan University of TechnologyWuhan 430063China Hubei Key laboratory of Inland Shipping Technology Wuhan University of TechnologyWuhan 430063China

In the present paper,the spatio-temporal evolution of vorticity in the first wake instability,i.e.,(pure)mode A,is investigated in order to understand the wake vortex dynamics and sign relationships among vorticity *** numerical simulation(DNS)for the flow past a circular cylinder is performed,typically at a Reynolds number of 200,in the three-dimensional(3-D)wake *** to characteristics of time histories of fluid forces,three different stages are identified as the computational transition,the initial stage and fully developed *** the second initial stage,the original two-dimensional spanwise vortices become obviously three-dimensional associated with the streamwise or vertical vorticity intensified up to about *** a matter of fact,these additional vorticities,caused by the intrinsic 3-D instability,are already generated firstly on cylinder surfaces early in the computational transition,indicating that the three-dimensionality appeared early near the *** evolution of additional components of vorticity with features the same as mode A shows that(pure)mode A can be already formed in the late computational *** careful analysis of the vorticity field on the front surface,in the shear layers and near wake at typical times,two sign laws are *** illustrate intrinsic relationships among three vorticity components,irrelevant to the wavelength or Fourier mode and Reynolds number in(pure)mode *** importantly,the origin of streamwise vortices is found and explained by a new physical mechanism based on the theory of vortex-induced *** a result,the whole process of formation and shedding vortices with these vorticities is firstly and completely *** characteristics are presented in detail.

关键词： Wake transition Circular cylinder Vorticity mode A Sign law

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Effect of perforation on flow past a conic cylinder at Re =100: wavy vortex and sign laws

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Acta mechanica Sinica 2018年第5期34卷 812-829页

作者： l.m.lin X.F.Zhong Y.X.Wu Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

In order to find the intrinsic physical mechanism of the original Kármán vortex wavily distorted across the span due to the introduction of three-dimensional (3-D) geometric disturbances,a flow past a peak-perforated conic shroud is numerically simulated at a Reynolds number of *** on previous work by meiburg and lasheras (1988),the streamwise and vertical interactions with spanwise vortices are introduced and *** vortex-shedding patterns in the near wake for different flow regimes are reinspected and illustrated from the view of these two ***,in regime Ⅰ,spanwise vortices are a little distorted due to the weak *** in regime Ⅱ,spanwise vortices,even though curved obviously,are still shed synchronously with moderate streamwise and vertical *** in regime Ⅲ,violently wavy spanwise vortices in some vortex-shedding patterns,typically an Ω-type vortex,are mainly attributed to the strong vertical interactions,while other cases,such as multiple vortex-shedding patterns in sub-regime Ⅲ-D,are resulted from complex streamwise and vertical interactions.A special phenomenon,spacial distribution of streamwise and vertical components of vorticity with specific signs in the near wake,is analyzed based on two models of streamwise and vertical vortices in explaining physical reasons of top and bottom shear layers wavily varied across the *** these two models and above two interactions are *** two sign laws are summarized:the first sign law for streamwise and vertical components of vorticity is positive in the upper shear layer,but negative in the lower shear layer,while the second sign law for three vorticity components is always negative in the wake.

关键词： Vortex-shedding pattern Flow control Vortex dynamics Conic disturbance Perforation Sign law

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Effect of perforation on flow past a conic cylinder at Re=100:vortex-shedding pattern and force history

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Acta mechanica Sinica 2018年第2期34卷 238-256页

作者： l.m.lin X.F.Zhong Y.X.Wu Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences

The flow past a circular-section cylinder with a conic shroud perforated with four holes at the peak was simulated numerically at Re = 100, considering two factors, *** angle of attack and the diameter of the holes. The effects of the perforated conic shroud on the vortex shedding pattern in the near wake was mainly investigated, as well as the time history of the drag and lift forces. In the investigated parameter space, three flow regimes were generally identified, corresponding to weak, moderate, and strong disturbance *** regime I, the wake can mainly be described by alternately shedding Kármán or Kármán-like vortices. In regime II, the spanwise vortices are obviously disturbed along the span due to the appearance of additional vorticity components and their interactions with the spanwise vortices, but still shed in synchronization along the spanwise direction. In regime III,the typical Kármán vortices partially or totally disappear,and some new vortex shedding patterns appear, such as-type, obliquely shedding, and crossed spanwise vortices with opposite sign. Corresponding to these complex vortex shedding patterns in the near wake, the fluid forces no longer oscillate regularly at a single vortex shedding frequency, but rather with a lower modulation frequency and multiple amplitudes. An overview of these flow regimes is presented.

关键词： Vortex shedding pattern Fluid forces Flow control Conical shroud Perforation

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New interpretation of specific sign of Reynolds stress in the boundary layer on a flat plate

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Theoretical & Applied mechanics letters 2018年第6期8卷 372-377,I0003页

作者： l.m.lin Y.X.Wu Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences School of Engineering Sciences University of Chinese Academy of Sciences

The specific sign of Reynolds stress in the boundary layer on a flat plate at zero incidence is newly interpreted in present paper based on the theory of vortex-induced vortex. It avoids some problems appeared in a traditional explanation, on the basis of relationship between mean and fluctuating flows due to the transport of momentum. Through the analysis of local flow field in the immediate neighborhood of wall, the characteristics of Reynolds stress are identified through introducing turbulence-induced small-scale streamwise eddies above the flat plate. The positive Reynolds stress is theoretically verified. And such new interpretation illustrates that the generation of Reynolds stress, as well as fluctuating velocity, is intrinsically independent of the mean flow. But its specific sign would be determined by the mean flow due to the inertial forces. Other features,such as the intensity relationship among three components of fluctuating velocity, are also presented.

关键词： Reynolds shear stress Sign Boundary layer Flatplate Turbulence

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mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex

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Acta mechanica Sinica 2019年第1期35卷 1-14,I0001页

作者： l.m.lin S.Y.Shi X.F.Zhong Y.X.Wu Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

As reported in a previous work by lin et al.(Acta meeh Sin, 2018. https://***/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake.

关键词： Wavy vortex Sign law Vortex-induced vortex Wake Bluff body

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Intrinsic relationship of vorticity between modes A and B in the wake of a bluff body

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Theoretical & Applied mechanics letters 2018年第5期8卷 320-325,362页

作者： l.m.lin S.Y.Shi Y.X.Wu Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of Sciences School of Engineering Sciences University of Chinese Academy of Sciences

The intrinsic physical relationship of vorticity between modes A and B in the three-dimensional wake transition is *** numerical simulations for the flow past a square-section cylinder are carried out at Reynolds numbers of 180 and 250,associated with modes A and B,*** on the analysis of spacial distributions of vorticity in the near wake,characteristics of the vertical vorticity in modes A and B are ***,the relationship of three vorticity components with specific signs is summarized into two sign laws,as intrinsic physical relationships between two instability *** the theory of vortex-induced vortex,such two sign laws confirm that there are two and only two kinds of vortex-shedding patterns in the near wake,just corresponding to modes A and *** brief,along the free stream direction,mode A can be described by the parallel shedding vertical vortices with the same sign,while mode B is described by the parallel shedding streamwise vortices with the same ***,it is found out that the|-type vortex is a basic kind of vortex structure in both modes A and B.

关键词： mode A mode B Wake Bluff body Sign law

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Transfer RNA-derived small RNA serves as potential non-invasive diagnostic marker and a novel therapeutic target for acute pancreatitis

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World Journal of Gastroenterology 2025年第1期31卷 152-156页

作者： Jing Zhang Chun-lin Ou Department of Immunology School of Basic MedicineCentral South UniversityChangsha 410000Hunan ProvinceChina Department of Pathology Xiangya HospitalCentral South UniversityChangsha 410008Hunan ProvinceChina

Transfer RNA(tRNA)-derived fragments,a new type of tRNA-derived small RNA(tsRNA),can be cleaved from tRNA by enzymes to regulate target gene expression at the transcriptional and translational *** are not only degradation fragments but also have biological functions,including those in immune inflammation,metabolic disorders,and cell *** dysregulation is closely associated with multiple diseases,including various cancers and acute pancreatitis(AP).AP is a common gastrointestinal disease,and its incidence increases *** development is associated with tsRNAs,which regulate cell injury and induce inflammation,especially pyroptosis and ***,serum tRF36 has the potential to serve as a non-invasive diagnostic biomarker and leads to pancreatic acinar cell ferroptosis causing inflammation to promote *** show the characteristics of tsRNAs and their diagnostic value and function in AP,and discuss the potential opportunities and challenges of using tsRNAs in clinical applications and research.

关键词： Transfer RNA derived small RNAs Acute pancreatitis liquid biopsy Biomarker Cell pyroptosis Ferroptosis

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Effect of cholesterol metabolism on hepatolithiasis

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World Journal of Gastroenterology 2025年第1期31卷 157-162页

作者： lin Zheng Zi-Yu Ye Jun-Ji ma Department of Gastroenterology The Second Hospital of Hebei Medical UniversityHebei Key Laboratory of GastroenterologyHebei Institute of GastroenterologyHebei Clinical Research Center for Digestive DiseasesNo.215 Heping West RoadShijiazhuang 050000Hebei ProvinceChina

Surgical intervention is currently the primary treatment for hepatolithiasis;how-ever,some patients still experience residual stones and high recurrence rates after *** metabolism seems to play an important role in hepatoli-thiasis pathogenesis.A high cholesterol diet is one of the significant reasons for the increasing incidence of ***,regular diet and appropriate medical intervention are crucial measures to prevent hepatolithiasis and reduce recurrence rate after *** dietary cholesterol and drugs that increase cholesterol stone solubility are key therapeutic approaches in treating *** article discusses the cholesterol metabolic pathways related to the pathogenesis of hepatolithiasis,as well as food intake and targeted therapeutic drugs.

关键词： Hepatolithiasis Cholesterol metabolism High-fat diet 3-hydroxy-3-methylglutaryl-coenzyme A reductase Interlobular bile duct

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Pyroptosis,ferroptosis,and autophagy in spinal cord injury:regulatory mechanisms and therapeutic targets

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Neural Regeneration Research 2025年第10期20卷 2787-2806页

作者： Qingcong Zheng Du Wang Rongjie lin Weihong Xu Department of Spinal Surgery the First Affiliated Hospital of Fujian Medical UniversityFuzhouFujian ProvinceChina Arthritis Clinical and Research Center Peking University People’s HospitalBeijingChina Department of Orthopedic Surgery Fujian Medical University Union HospitalFuzhouFujian ProvinceChina

Regulated cell death is a form of cell death that is actively controlled by *** studies have shown that regulated cell death plays a key role after spinal cord *** and ferroptosis are newly discovered types of regulated cell deaths that have been shown to exacerbate inflammation and lead to cell death in damaged spinal ***,a complex form of cell death that is interconnected with various regulated cell death mechanisms,has garnered significant attention in the study of spinal cord *** injury triggers not only cell death but also cellular survival *** signaling pathways play pivotal roles in influencing the processes of both deterioration and repair in spinal cord injury by regulating pyroptosis,ferroptosis,and ***,this review aims to comprehensively examine the mechanisms underlying regulated cell deaths,the signaling pathways that modulate these mechanisms,and the potential therapeutic targets for spinal cord *** analysis suggests that targeting the common regulatory signaling pathways of different regulated cell deaths could be a promising strategy to promote cell survival and enhance the repair of spinal cord ***,a holistic approach that incorporates multiple regulated cell deaths and their regulatory pathways presents a promising multi-target therapeutic strategy for the management of spinal cord injury.

关键词： autophagy cell death ferroptosis inflammation pathological mechanisms pyroptosis regulated cell death regulatory pathways spinal cord injury therapeutic targets

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Prussian Blue Analogue‑Templated Nanocomposites for Alkali‑Ion Batteries:Progress and Perspective

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Nano-micro letters 2025年第1期17卷 216-261页

作者： Jian‑En Zhou Yilin li Xiaoming lin Jiaye Ye Key laboratory of Theoretical Chemistry of Environment Ministry of EducationSchool of ChemistrySouth China Normal UniversityGuangzhou 510006People’s Republic of China School of Chemistry and Physics Faculty of ScienceQueensland University of Technology2 George StreetBrisbaneQLD 4000Australia Centre for materials Science Queensland University of Technology2 George StreetBrisbaneQLD 4000Australia

lithium-ion batteries(lIBs)have dominated the portable electronic and electrochemical energy markets since their commercialisation,whose high cost and lithium scarcity have prompted the development of other alkali-ion batteries(AIBs)including sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).Owing to larger ion sizes of Na^(+)and K^(+)compared with li^(+),nanocomposites with excellent crystallinity orientation and well-developed porosity show unprecedented potential for advanced lithium/sodium/potassium *** enticing open rigid framework structures,Prussian blue analogues(PBAs)remain promising self-sacrificial templates for the preparation of various nanocomposites,whose appeal originates from the well-retained porous structures and exceptional electrochemical activities after thermal *** review focuses on the recent progress of PBA-derived nanocomposites from their fabrication,lithium/sodium/potassium storage mechanism,and applications in AIBs(lIBs,SIBs,and PIBs).To distinguish various PBA derivatives,the working mechanism and applications of PBA-templated metal oxides,metal chalcogenides,metal phosphides,and other nanocomposites are systematically evaluated,facilitating the establishment of a structure–activity correlation for these *** on the fruitful achievements of PBA-derived nanocomposites,perspectives for their future development are envisioned,aiming to narrow down the gap between laboratory study and industrial reality.

关键词： Prussian blue analogues Self-sacrificial template lithium-ion batteries Sodium-ion batteries Potassium-ion batteries

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