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Large eddy simulations of zinc ions transfer to turbulent flows from hyporheic zone

JOURNAL OF HYDRODYNAMICS 2024年第4期36卷 650-661页

作者： Jin, Yi-ming Chen, Jin-feng Zhang, Jin-long Zhao, Ze-hao Fan, dong-liang dong, yu-hong Shanghai Univ Shanghai Key Lab Mech Energy Engn Shanghai Inst Appl Math & Mech Shanghai Frontier Sci Ctr Mechanoinformat Shanghai 200072 Peoples R China Shanghai Inst Aircraft Mech & Control Shanghai 200092 Peoples R China

Metal contaminants from surface water pollution events often enter hyporheic zones, under certain conditions, they may be released back into streams, causing secondary pollution to the water quality. The present study investigated the effects of adsorption, permeability, and anisotropy of sediment beds on the release of zinc ions (Zn2+) from the hyporheic zone into overlying turbulent flows using large-eddy simulations (LES). The volume-averaged Navier-Stokes equations and advection-diffusion equation with adsorption term were used to describe the sediment in-flow, adsorption, and convective diffusion of Zn2+ within the sediment layer. The effects of sediment permeability on the Zn2+ concentration distribution and mass transfer processes were investigated by time-averaged statistics of flow and concentration fields. The results show that adsorption becomes stronger as the pH value increases, leading to a slow increase in Zn2+ concentration in the overlying water layer and reaching a lower steady-state concentration. Higher overall permeability of the sediment layer can enhance mass and momentum exchange near the sediment-water interface (SWI), and intensify the release of Zn2+ from the sediment layer into the overlying water. As the wall-normal permeability of the sediment layer increases, the normal turbulent intensity strengthens, momentum transport enhances, the wall-normal Zn2+ concentration flux increases, the effective diffusion coefficient increases, and the concentration in the overlying water increases.

关键词： Zn2+ contaminants adsorption hyporheic exchange turbulent flow large eddy simulation (LES) DIRECT NUMERICAL-SIMULATION OPEN-CHANNEL FLOW TRANSPORT EXCHANGE SEDIMENT

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Heat transfer and flow structure in centrally-confined 2-D Rayleigh-Bénard convection

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JOURNAL OF HYDRODYNAMICS 2024年第4期36卷 772-780页

作者： Sun, Cong Wu, Jian-zhao Meng, Xiao-hui Liu, Cai-xi Xu, Wei dong, yu-hong Zhou, Quan Shanghai Univ Shanghai Key Lab Mech Energy Engn Shanghai Inst Appl Math & Mech Sch Mech & Engn Sci Shanghai 200072 Peoples R China Sci & Technol Res Inst Co Ltd China Elect Equipment Grp Shanghai 200040 Peoples R China

Through direct numerical simulations, we investigated the flow structure and heat transfer of the centrally confined 2-D Rayleigh-B & eacute;nard (RB) convection over the Rayleigh number range 9 x 105 <= Ra <= 109 at a fixed Prandtl number Pr = 4.3. It is found that with increasing Ra, the number of convection rolls in the central vertical channel increases from zero to three. When there is no rolls in the vertical channel, the convective flow in central region is significantly influenced by the boundary layer, whereas when the convection rolls is generated in the vertical channel, the convective flows in central regions is free from the boundary layer limitation, and by defining the characteristic length, one obtains the heat transfer scaling law relation in vertical channel, i.e., Nuvc similar to Ravc0.476 +/- 0.005, which could be the evidence of "ultimate regime".

关键词： Rayleigh-B & eacute nard (RB) turbulence heat transport vertical channel ultimate regime

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On capped Higgs positivity cone

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中国科学技术大学学报 2024年第7期54卷 44-54,43,I0003页

作者： dong-yu hong Zhuo-Hui Wang Shuang-Yong Zhou Interdisciplinary Center for Theoretical Study University of Science and Technology of ChinaHefei 230026China Peng Huanwu Center for Fundamental Theory Hefei 230026China

The Wilson coefficients of the standard model effective field theory are subject to a series of positivity *** has been shown that while the positivity part of the ultraviolet(UV)partial wave unitarity leads to the Wilson coefficients living in a convex cone,further including the nonpositivity part caps the cone from *** Higgs scattering,a capped positivity cone was obtained using a simplified,linear unitarity condition without utilizing the full internal symmetries of Higgs ***,we further implement stronger nonlinear unitarity conditions from the UV,which generically gives rise to better *** show that,for the Higgs case in particular,while the nonlinear unitarity conditions per se do not enhance the bounds,the fuller use of the internal symmetries do shrink the capped positivity cone significantly.

关键词： positivity bounds standard model effective field theory(SMEFT) Higgs

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THE NONLINEAR BEHAVIOR OF INTERFACE BETWEEN TWO-PHASE SHEAR FLOW WITH LARGE DENSITY RATIOS

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Journal of Hydrodynamics 2006年第5期18卷 587-592页

作者： dong yu-hong Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The Navier-Stokes equations for the two-dimensional incompressible flow are used to investigate the effects of the Reynolds number and the Weber number on the behavior of interface between liquid gas shear flow. In the present study, the density ratios are fixed at approximately 10^0-10^3. The interface between the two phases is resolved using the level-set approach. The Reynolds number and the Weber number, based on the gas, are selected as 400-10000 and 40-5000, respectively. In the past, simulations reappeared the amplitude of interface growth predicted by viscous Orr-Sommerfeld linear theory, verifying the applicability and accuracy of the numerical method over a wide range of density and viscosity ratios; now, the simulations show that the nonlinear development of ligament elongated structures and resulted in the subsequent breakup of the heavier fluid into drops.

关键词： two-phase shear flow large density ratios immiscible interface level set approach

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乌汶伯克霍尔德菌P5和格氏假单胞菌RP22促杉木生长机制探究

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林业科学研究 2024年第5期37卷 33-45页

作者：陈详腾魏书蒙焦如珍董玉红林木资源高效生产全国重点实验室中国林业科学研究院林业研究所北京100091

[目的]本文拟探究乌汶伯克霍尔德氏菌P5和格氏假单胞菌RP22对杉木幼苗生长、基因表达和土壤性质的影响,初步揭示2种溶磷菌促杉木生长机制。[方法]以6个月苗龄的杉木实生苗为试验材料,将配制好的P5、RP22及P5+RP22菌剂通过根灌方式施加,... 详细信息

[目的]本文拟探究乌汶伯克霍尔德氏菌P5和格氏假单胞菌RP22对杉木幼苗生长、基因表达和土壤性质的影响,初步揭示2种溶磷菌促杉木生长机制。[方法]以6个月苗龄的杉木实生苗为试验材料,将配制好的P5、RP22及P5+RP22菌剂通过根灌方式施加,每月施加一次,持续3个月。3个月后对幼苗和土壤进行取样,测定幼苗的生长生理指标和土壤指标;基于Illumina HiSeq 4000测序平台对幼苗进行转录组分析,并筛选杉木幼苗的促生基因。[结果]与对照组(CK)相比,3种菌剂处理均促进杉木幼苗的生长。3种菌剂对杉木幼苗的促生生理机制包括:PSB提高了杉木幼苗的叶绿素、可溶性糖、可溶性蛋白等生理指标及磷含量;同时,增加了土壤有效磷、速效钾、全磷养分含量。转录组结果表明,3种菌剂处理后杉木幼苗的差异表达基因(DEGs)均显著富集在代谢物合成、苯丙烷生物合成、亚油酸代谢、α亚麻酸代谢和光合作用通路。对这些通路的深入分析发现,PAL、COMT、4CL、LOX1_5、AOS、AOC等基因在P5菌剂处理组显著上调;PAL、TOGT1、CYP73A、LOX1_5、psbS、psaF等基因在RP22菌剂处理组显著上调;LOX1_5、psbO、petH、psaF等基因在P5+RP22菌剂处理组显著上调,表明3种PSB菌剂对杉木幼苗的促生机制是多个代谢通路相互协调的结果。[结论]3种菌剂能通过调控杉木幼苗的生理、提高土壤养分含量和上调表达苯丙烷生物合成、亚油酸代谢、光合作用等通路中的基因,从而促进杉木幼苗生长。

关键词：杉木幼苗溶磷菌转录组差异表达基因促生机理

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Composition and distribution of ground-dwelling beetles among oak fragments and surrounding pine plantations in a temperate forest of North China

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Insect Science 2014年第1期21卷 114-124页

作者： Xiao-dong yu Tian-hong Luo hong-Zhang Zhou Key Laboratory of Zoological Systematics and Evolution Institute of Zoology Chinese Academy of Sciences Beijing China

In this study, we compared ground-dwelling beetle assemblages （Coleoptera） from a range of different oak fragments and surrounding conifer plantations to evaluate effects of forest size and surrounding matrix habitat in a temperate forest of north China. During 2000, beetles were sampled via pitfall traps within two large oak fragments （ca. 2.0-4.0 ha）, two small oak fragments （ca. 0.2-0.4 ha） and two surrounding matrices dom- inated by pine plantations （〉4 ha） in two sites of different aspects. Overall, no significantly negative effects from forest patch size and the surrounding matrix habitat were detected in total species number and abundance of ground-dwelling beetles. However, compared with small oak patches or pine plantations, more species were associated with an affinity for at least one large oak patch of the two aspects. Multivariate regression trees showed that the habitat type better determined the beetle assemblage structure than patch size and aspect, indicating a strong impact of the surrounding matrix. Linear mixed models indicated that species richness and abundance of all ground-dwelling beetles or beetle families showed different responses to the selected environmental variables. Our results suggest that more disturbed sites are significantly poorer in oak forest specialists, which are usually more abundant in large oak fragments and decrease in abundance or disappear in small fragments and surrounding matrix habitats. Thus, it is necessary to preserve a minimum size of forest patch to create conditions characteristic for forest interior, rather than the more difficult task of increasing habitat connectivity.

关键词： forest patch size fragmentation ground-dwelling beetles North China,surrounding matrix habitat temperate forest

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The saproxylic beetle assemblage associated with different host trees in Southwest China

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Insect Science 2008年第3期15卷 251-261页

作者： Jie Wu Xiao-dong yu hong-Zhang Zhou Institute of Zoology Chinese Academy of Sciences Beijing China

Dead wood is a habitat for many insects and other small animals, some of which may be rare or endangered and in need of effective protection. In this paper, saproxylic beetle assemblages associated with different host trees in the subtropical forests in southwestern China were investigated. A total of 277 species （1 439 specimens） in 36 beetle families were collected from 117 dead wood samples, of which 101 samples were identified and respectively belonged to 12 tree genera. The number of saproxylic beetle species varied greatly among logs of different tree genera, with the highest diversity on logs of Juglans. Generally, broad-leaved trees had a higher richness and abundance of saproxylic species than coniferous trees. Cluster analysis revealed that assemblages from broad-leaved tree genera were generally similar （except for Betula） and assemblages from coniferous trees formed another distinct cluster. The subsequent indicator analysis proposed that there are different characteristic species for different cluster groups of host tree genera. In our study, log diameter has no positive influence on beetle species density. Conversely, comparisons of individual-based rarefaction curves suggested that beetle species richness was highest in the small diameter class both in coniferous and broad-leaved tree genera. With increased wood decay, proportion of habitat specialists （saproxylic beetles living on one tree genus） decreased, whereas proportion of habitat generalists （living on more than three tree genera） increased. The beetle species density was found to be higher in early stages, and decreased in later stages as well. A negative influence of altitude on saproxylic beetle species richness and abundance was detected. It was indicated that different tree genera and altitudes possibly display cross effects in modulating the altitudinal distribution and host preference of the beetles.

关键词： China host trees Saproxylic beetle subtropical forest

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Pressure Effects on Thermodynamics of Phase Behavior in Polystyrene/Methylcyclohexane Solutions

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Chemical Research in Chinese Universities 2007年第5期23卷 613-621页

作者： LI hong-fei JIANG Shi-chun AN Li-jia yu dong-hong State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 P. R. China Section of Chemistry Department of Life Sciences Aalborg University Aalborg DK 9000 Denmark

The calculations presented in this paper are based on the Sanchez-Lacombe（SL）lattice fluid *** interaction energy parameter,g12/k,required in this approach was obtained by fitting the cloud points of polystyrene（PS）/methylcyclohexane（MCH）polymer solutions under *** SL lattice fluid theory was used to calculate the spinodals,the binodals,and the Flory-Huggins（FH）interaction parameter of the *** calculated results show that the SL lattice fluid theory can describe the dependences of thermodynamics of PS/MCH solutions on temperature and pressure very ***,the calculated enthalpy and the excess volume changes indicate that the Clausius-Clapeyron equation cannot be suitable to describe pressure effect on PS/MCH *** analysis on the thermodynamics of this system under pressure shows that the role of entropy is more important than the excess volume in the present case.

关键词： PS/MCH polymer solution Thermodynamics Pressure effect

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The driven cavity turbulent flow with porous walls: Energy transfer, dissipation, and time-space correlations

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Journal of Hydrodynamics 2021年第4期33卷 712-724页

作者： Wen-wu Yang Bo-fu Wang Quan Zhou yu-hong dong Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The energy transfer and dissipation as well as the turbulent structures in a lid-driven cavity flow with porous walls are investigated via the lattice Boltzmann method, with direct numerical simulation (DNS) for an isothermal incompressible flow for which the Reynolds number (Re) is 50 000. A generalized Navier-Stokes equation with the Brinkman-Forchheimer-extended Darcy model is implemented, in which the presence of permeable walls is taken into account. This study focuses on the modulations of the flow field due to porous walls, by comparing with the results from the cavity flow bounded with smooth walls. Firstly, we derived the exact expression of the kinetic energy dissipation rate in a cavity to study the budget balance of the induced and dissipated kinetic energy. By decomposing the total kinetic energy dissipation into the componential contributions of the viscous and porous medium layer, we found that the kinetic energy dissipated in the thin porous layer occupies 37% of the total driven lid-induced kinetic energy in the present parameters. Then we found that the time-averaged kinetic energy, turbulent kinetic energy (TKE), as well as the strength of the large-scale energy-containing eddy, and secondary eddies are significantly attenuated. Furthermore, it is found that the momentum and kinetic energy transfer near the corners are vastly decreased. Finally, the space-time velocity correlation functions are also provided to examine the decorrelation property of small eddies by means of convection and distortion motions in the cavity turbulent field.

关键词： Cavity turbulent flow porous medium energy transfer dissipation time-space correlations

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Tuning turbulent convection through rough element arrangement

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Journal of Hydrodynamics 2022年第2期34卷 308-314页

作者： Jian-zhao Wu Dao-liang dong Bo-fu Wang yu-hong dong Quan Zhou Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The tuning of turbulent Rayleigh-Bénard(RB)convection in a box is realized numerically by designed rough element *** the nonlinear dynamics of the thermal turbulence system,five models with rough elements of different widths and the same height are proposed to tune the fluid flow heat-transport *** simulations are performed using spectral element method for Rayleigh number in the range 10^(6)≤Ra≤10^(9) and a fixed Prandtl number Pr=*** is found that heat transport is enhanced for large roughness widths as the interaction between the large-scale circulation and secondary flows inside the cavity regions between the rough elements promotes the eruptions of thermal plumes,but is suppressed for small ones as more heat are trapped inside the *** all the rough models studied,different scaling exponents for the heat transport are identified and the influences of roughness arrangement on flow structure are studied.

关键词： Rayleigh-Bénard(RB)turbulence heat transport roughness arrangement

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