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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

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

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

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Journal of Hydrodynamics 2024年第4期36卷 650-661页

作者： Yi-ming Jin Jin-feng Chen Jin-long Zhang Ze-hao Zhao dong-liang Fan yu-hong dong Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai200072China Shanghai Institute of Aircraft Mechanics and Control Shanghai200092China

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 *** present study investigated the effects of adsorption,permeability,and anisotropy of sediment beds on the release of zinc ions(Zn^(2+))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 Zn^(2+) within the sediment *** effects of sediment permeability on the Zn^(2+)concentration distribution and mass transfer processes were investigated by time-averaged statistics of flow and concentration *** results show that adsorption becomes stronger as the pH value increases,leading to a slow increase in Zn^(2+)concentration in the overlying water layer and reaching a lower steady-state *** overall permeability of the sediment layer can enhance mass and momentum exchange near the sediment-water interface(SWI),and intensify the release of Zn^(2+)from the sediment layer into the overlying *** the wall-normal permeability of the sediment layer increases,the normal turbulent intensity strengthens,momentum transport enhances,the wall-normal Zn^(2+)concentration flux increases,the effective diffusion coefficient increases,and the concentration in the overlying water increases.

关键词： Zn^(2+)contaminants adsorption hyporheic exchange turbulent flow large eddy simulation(LES)

An efficient parallel algorithm for DNS of buoyancy-driven turbulent flows

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Journal of Hydrodynamics 2019年第6期31卷 1159-1169页

作者： Yi-zhao Zhang Shu-ning Xia yu-hong dong Bo-fu Wang Quan Zhou Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China

In this paper,an explicit low-storage simplified M-stage Runge-Kutta(SRK)scheme for high Reynolds-number incompressible flows is *** the SRK scheme,the Poisson equation is solved only once in the final substage of each time *** taking advantage of the SRK scheme and the advanced hybrid MPI+MPI model,we have developed an efficient parallel solver for buoyancy-driven turbulent *** spatial and temporal accuracies of the solver are validated with Taylor-Green vortex *** the RK and SRK schemes are implemented for the simulation of turbulent Rayleigh-Benard convection as well as Rayleigh-Taylor *** results show that the SRK scheme can save approximately 20%of the computation time.

关键词： Direct numerical simulation(DNS) parallel algorithm turbulent flows

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： Cong Sun Jian-zhao Wu Xiao-hui Meng Cai-xi Liu Wei Xu 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 China Electrical Equipment Group Research Institute of Science and Technology Co.Ltd. Shanghai200072China

Through direct numerical simulations,we investigated the flow structure and heat transfer of the centrally confined 2-D Rayleigh-Bénard(RB)convection over the Rayleigh number range 9×10^(5)≤Ra≤10^(9) at a fixed Prandtl number Pr=*** is found that with increasing Ra,the number of convection rolls in the central vertical channel increases from zero to *** 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.,Nu_(vc)∼Ra_(vc)^(0.476±0.005),which could be the evidence of“ultimate regime”.

关键词： Rayleigh-Benard(RB)turbulence heat transport vertical channel ultimate regime

Lattice Boltzmann simulations of turbulent shear flow between parallel porous walls

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Applied Mathematics and Mechanics(English Edition) 2014年第12期35卷 1479-1494页

作者：唐政刘难生董宇红 Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Department of Modern Mechanics University of Science and Technology of China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

The effects of two parallel porous walls are investigated, consisting of the Darcy number and the porosity of a porous medium, on the behavior of turbulent shear flows as well as skin-friction drag. The turbulent channel flow with a porous surface is directly simulated by the lattice Boltzmann method （LBM）. The Darcy-Brinkman- Forcheimer （DBF） acting force term is added in the lattice Boltzmann equation to simu- late the turbulent flow bounded by porous walls. It is found that there are two opposite trends （enhancement or reduction） for the porous medium to modify the intensities of the velocity fluctuations and the Reynolds stresses in the near wall region. The parametric study shows that flow modification depends on the Darcy number and the porosity of the porous medium. The results show that, with respect to the conventional impermeable wall, the degree of turbulence modification does not depend on any simple set of param- eters obviously. Moreover, the drag in porous wall-bounded turbulent flow decreases if the Darcy number is smaller than the order of O（10-4） and the porosity of porous walls is up to 0.4.

关键词： lattice Boltzmann method (LBM) porous material wall-bounded turbu-lence Darcy number drag coefficient

Reactivation of Epstein-Barr virus in SFTSV infected patients

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Infectious Medicine

Infectious Medicine 2023年第3期2卷 195-201页

作者： Li-Zhu Fang yu-hong dong Zhi-Jian Yan Chuan-Min Zhou Xue-Jie yu Xiang-Rong Qin Qingdao City Center for Disease Control and Prevention Qingdao 266033China Sixth People’s Hospital Qingdao 266033China State Key Laboratory of Virology School of Public HealthWuhan UniversityWuhan 430071China Department of Clinical Laboratory the Second Hospital of Shandong UniversityJinan 250033China

Background:Severe fever with thrombocytopenia syndrome(SFTS)is an emerging hemorrhagic fever caused by a tick-borne bunyavirus SFTSV with case fatality up to 30%.The reactivation of Epstein-Barr virus(EBV)has been proven to occur in individuals with various immune suppression ***:Here,we diagnosed 22 SFTSV infected patients with PCR in a hospital in Shandong Province,China in *** understand the consequences of SFTSV infection leading to EBV reactivation,we examined EBV reactivation in SFTSV-infected patients with PCR and ***:We found that EBV was reactivated in 18.2%(4/22)of SFTS patients,suggesting that EBV reactivation is common in SFTS *** with SFTS patients without EBV reactivation,SFTS patients with EBV-reactivation had a significantly lower median level of serum albumin(32.45 g/L vs.26.95 g/L,p=0.03)and a significantly higher median number of urine red blood cells(0 cells/μL vs.9 cells/μL,p=0.04).Conclusion:SFTS infection can reactivate EBV in patients,which may make the clinical condition of patients worsen.

关键词： Severe fever with thrombocytopenia syndrome virus Epstein-Barr virus Reactivation Glomerular injury

Basic transcription factor 3 is involved in gastric cancer development and progression

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World Journal of Gastroenterology 2013年第28期19卷 4495-4503页

作者： Qi Liu Jian-Ping Zhou Bin Li Zhong-Cheng Huang hong-yu dong Guang-Yi Li Ke Zhou Shao-Lin Nie Department of Anorectal Surgery People's Hospital of Hunan Province the First Affiliated Hospital of Hunan Normal University Department of Elderly Surgery the Second Xiangya Hospital of Central South University Department of Tumor Chemotherapy Xiangya Hospital of Central South University Department of Gastrointestinal Surgery Hunan Provincial Tumor Hospital theAffiliated Tumor Hospital of Central South University

AIM: To further analyse cancer involvement of basic transcription factor 3 (BTF3) after detection of its upregulation in gastric tumor samples. METHODS: BTF3 transcription rates in human gastric tumor tissue samples (n = 20) and adjacent normal tissue (n = 18) specimens as well as in the gastric cancer cell lines AGS, SGC-7901, MKN-28, MKN-45 and MGC803 were analyzed via quantitative real-time polymerase chain reaction. The effect of stable BTF3 silencing via infection with a small interfering RNA (siRNA)-BTF3 expressing lentivirus on SGC-7901 cells was measured via Western blotting analysis, proliferation assays, cell cycle and apoptosis profiling by flow cytometry as well as colony forming assays with a Cellomic Assay System. RESULTS: A significant higher expression of BTF3 mRNA was detected in tumors compared to normal gastric tissues (P < 0.01), especially in section tissues from female patients compared to male patients, and all tested gastric cancer cell lines expressed high levels of BTF3. From days 1 to 5, the relative proliferation rates of stable BTF3-siRNA transfected SGC7901 cells were 82%, 70%, 57%, 49% and 44% compared to the control, while the percentage of cells arrested in the G 1 phase was significantly decreased (P = 0.000) and the percentages of cells in the S (P = 0.031) and G 2 /M (P = 0.027) phases were significantly increased. In addition, the colony forming tendency was significantly decreased (P = 0.014) and the apoptosis rate increased from 5.73% to 8.59% (P = 0.014) after BTF3 was silenced in SGC7901 cells. CONCLUSION: BTF3 expression is associated with enhanced cell proliferation, reduced cell cycle regulation and apoptosis and its silencing decreased colony forming and proliferation of gastric cancer cells.

关键词： Basic transcription factor 3 Gastric cancer Small interfering RNA Proliferation Apoptosis Cell cycle

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不同成因黄铁矿的物性差异及浮游性研究

中国矿业大学学报 2010年第5期39卷 758-764页

作者：于宏东孙传尧北京科技大学土木与环境工程学院北京100083 北京矿冶研究总院矿物加工科学与技术国家重点实验室北京100044

研究了5种不同成因黄铁矿的物性特征及其浮游性.结果表明:不同成因的黄铁矿颗粒内部结构不同,相同磨矿条件下其破裂方式有异,破裂后矿物表面形貌及表面原子分布密度也不同,因而用黄药作捕收剂时,不同成因的黄铁矿浮游性亦存在差别;黄铁... 详细信息

研究了5种不同成因黄铁矿的物性特征及其浮游性.结果表明:不同成因的黄铁矿颗粒内部结构不同,相同磨矿条件下其破裂方式有异,破裂后矿物表面形貌及表面原子分布密度也不同,因而用黄药作捕收剂时,不同成因的黄铁矿浮游性亦存在差别;黄铁矿的半导体类型与其浮游性间有一定联系,即除煤系沉积型黄铁矿外,p型黄铁矿的浮游性比n型黄铁矿的好.从矿物学的角度看,由形成条件决定的黄铁矿内部结构、半导体类型,以及破碎后矿物表面铁原子的分布密度是影响其浮游性的主要因素.

关键词：黄铁矿物性特征半导体类型浮游性