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Multiphase flow model developed for simulating gas hydrate transport in horizontal pipe

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Applied Mathematics and Mechanics(English Edition) 2016年第9期37卷 1193-1202页

作者： Shuai TANG caixi liu Yuhong DONG Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

The hydrate formation or dissociation in deep subsea flow lines is a challenging problem in oil and gas transport systems. The study of multiphase flows is complex while necessary due to the phase changes （i.e., liquid, solid, and gas） that occur with increasing the temperature and decreasing the pressure. A one-dimensional multiphase flow model coupled with a transient hydrate kinetic model is developed to study the characteristics of the multiphase flows for the hydrates formed by the phase changes in the pipes. The multiphase flow model is derived from a multi-fluid model, while has been widely used in modelling multiphase flows. The heat convection between the fluid and the ambient through the pipe wall is considered in the energy balance equation. The developed multiphase flow model is used to simulate the procedure of the hydrate transport. The results show that the formation of the hydrates can cause hold-up oscillations of water and gas.

关键词： multiphase flow hydrate slug flow phase change

Effect of inertial particles with different specific heat capacities on heat transfer in particle-laden turbulent flow

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Applied Mathematics and Mechanics(English Edition) 2017年第8期38卷 1149-1158页

作者： caixi liu Shuai TANG Yuhong DONG Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai 200072China

The effect of inertial particles with different specific heat on heat transfer in particle-laden turbulent channel flows is studied using the direct numerical simulation（DNS） and the Lagrangian particle tracking method. The simulation uses a two-way coupling model to consider the momentum and thermal interactions between the particles and turbulence. The study shows that the temperature fields display differences between the particle-laden flow with different specific heat particles and the particle-free flow,indicating that the particle specific heat is an important factor that affects the heat transfer process in a particle-laden flow. It is found that the heat transfer capacity of the particle-laden flow gradually increases with the increase of the particle specific heat. This is due to the positive contribution of the particle increase to the heat transfer. In addition,the Nusselt number of a particle-laden flow is compared with that of a particle-free *** is found that particles with a large specific heat strengthen heat transfer of turbulent flow, while those with small specific heat weaken heat transfer of turbulent flow.

关键词： turbulent laden turbulence inertial Reynolds Lagrangian momentum dissipation fluctuation incompressible

Characteristics of turbulence transport for momentum and heat in particle-laden turbulent vertical channel flows

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Acta Mechanica Sinica 2017年第5期33卷 833-845页

作者： caixi liu Shuai Tang Lian Shen Yuhong Dong Shanghai Institute of Applied Mathematics and Mechanics and Shanghai Key Laboratory of Mechanics in Energy and Environment Engineering Shanghai University Department of Mechanical Engineering and St.Anthony Falls Laboratory University of Minnesota

The dynamic and thermal performance of particle-laden turbulent flow is investigated via direction numerical simulation combined with the Lagrangian point-particle tracking under the condition of two-way coupling, with a focus on the contributions of particle feedback effect to momentum and heat transfer of turbulence. We take into account the effects of particles on flow drag and Nusselt number and explore the possibility of drag reduction in conjunction with heat transfer enhancement in particle-laden turbulent flows. The effects of particles on momentum and heat transfer are analyzed, and the possibility of drag reduction in conjunction with heat transfer enhancement for the prototypical case of particle-laden turbulent channel flows is addressed. We present results of turbulence modification and heat transfer in turbulent particle-laden channel flow, which shows the heat transfer reduction when large inertial particles with low specific heat capacity are added to the flow. However, we also found an enhancement of the heat transfer and a small reduction of the flow drag when particles with high specific heat capacity are involved. The present results show that particles, which are active agents, interact not only with the velocity field, but also the temperature field and can cause a dissimilarity in momentum and heat transport. This demonstrates that the possibility to increase heat transfer and suppress friction drag can be achieved with addition of particles with different thermal properties.

关键词： Direction numerical simulation (DNS) Lagrangian tracking approach Flow drag Heat transfer Particle-laden flow

Impact of spray droplets on momentum and heat transport in a turbulent marine atmospheric boundary layer

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Theoretical & Applied Mechanics Letters 2019年第2期9卷 71-78页

作者： Ming Pan caixi liu Qingxiang Li Shuai Tang Lian Shen Yuhong Dong Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Department of Mechanical Engineering and St.Anthony Falls Laboratory University of Minnesota Shanghai Key Laboratory of Mechanics in Energy and Environment Engineering

Droplet-laden turbulent airflow(i.e. the mixture of dry air and water vapor) in the marine atmospheric boundary layer is described by an open channel flow configuration in direct numerical simulation(DNS). The dispersed phase, the spray droplets are tracked in a Lagrangian framework, and their impact on the carrier airflow is modeled with the two-way coupling between the two phases. A wide-range droplet size is typically found near the air–sea interface according to the sea spray concentration function(SSCF). The interactions of the droplets with turbulent airflow including mass, momentum, and energy exchange are investigated here. We found a balancing mechanism exists in the droplet effects on the turbulent drag coefficient, since spray droplets lead to a decreased vertical turbulent momentum transport, but also lead to an increased droplet contribution to total drag coefficient. For the heat transfer, as droplet mass loading increasing, the total Nusselt number decreases due to the depression of turbulent heat flux and enhanced negative droplet convective flux.

关键词： Direct numerical simulation Air-sea interface Sea spray Turbulent airflow

平板电解槽内电解质湍流运动和传质的直接数值模拟(英文)

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计算物理 2013年第1期30卷 75-81页

作者：周晓兰刘财喜董宇红上海大学上海市应用数学和力学研究所上海200072 上海大学力学在能源工程中的应用重点实验室上海200072

应用流体动力学、传质学和电化学理论,建立三维电解槽二元电解质溶液湍流运动的物理和数学模型,针对Butler-Volmer定律下极限电流和恒电流两种情况,通过直接数值模拟研究电解质溶液传质和运动特性,分析不同Schmidt数对电解质溶液平均浓... 详细信息

应用流体动力学、传质学和电化学理论,建立三维电解槽二元电解质溶液湍流运动的物理和数学模型,针对Butler-Volmer定律下极限电流和恒电流两种情况,通过直接数值模拟研究电解质溶液传质和运动特性,分析不同Schmidt数对电解质溶液平均浓度和脉动浓度的影响,考察湍流的脉动量控制电沉积的过程规律.对瞬时脉动浓度云图的分析可知,在高Schmidt数下脉动浓度拟序结构间距密集,且集中在壁面附近,表明高Schmidt数下传质过程主要由近电极处薄层内的流动行为所主导.

关键词：湍流传质直接数值模拟电解质浓度 Schmidt数

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多孔壁面槽道湍流中的流动阻力和传热

上海大学学报（自然科学版） 2018年第3期24卷 378-391页

作者：张一凡刘财喜董宇红上海大学上海市应用数学和力学研究所上海200072

为了研究多孔介质壁面对槽道湍流流动及传热的影响,基于容积平均和局部热平衡法对含有多孔介质壁面槽道湍流的流场和热场进行直接数值模拟(direct numerical simulation,DNS),讨论了具有不同达西数和孔隙率的多孔介质固壁对剪切湍流的... 详细信息

为了研究多孔介质壁面对槽道湍流流动及传热的影响,基于容积平均和局部热平衡法对含有多孔介质壁面槽道湍流的流场和热场进行直接数值模拟(direct numerical simulation,DNS),讨论了具有不同达西数和孔隙率的多孔介质固壁对剪切湍流的阻力系数及传热Nusselt数的影响.研究结果表明,较高的孔隙率会产生较明显的减阻效应,而较高的达西数会提高传热效率.

关键词：多孔介质壁湍流流动减阻传热

基于“MBK3”模式的三级公立医院护理绩效目标考核管理实践

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浙江医学教育 2021年第5期20卷 41-44页

作者：高薇薇杨舒岚刘彩霞浙江中医药大学浙江杭州310053 浙江医院浙江杭州310013

目的:探讨"MBK3"模式在三级公立医院护理绩效目标考核管理的方案与实施成效。方法:建立体系化绩效目标考核方案,进行管理、运作,收集考核结果数据并进行分析。结果:各护理单元目标考核均分由2018年的(83.43±2.84)分上升至2020年的(89.6... 详细信息

目的:探讨"MBK3"模式在三级公立医院护理绩效目标考核管理的方案与实施成效。方法:建立体系化绩效目标考核方案,进行管理、运作,收集考核结果数据并进行分析。结果:各护理单元目标考核均分由2018年的(83.43±2.84)分上升至2020年的(89.69±3.14)分,其中学习与成长维度得分由2018年的(13.17±0.70)分上升至2020年的(16.30±0.96)分,差异有统计学意义(P<0.05)。结论:以"MBK3"模式进行护理绩效目标考核,有利于护理管理的精细化、科学化,对实现考核管理促进护理整体绩效提升有积极意义。

关键词： MBK3 护理绩效目标考核管理

早孕期联合母体危险因素和平均动脉压预测子痫前期的效能评估

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现代妇产科进展 2024年第6期33卷 410-416,426页

作者：李彩曦陈震宇刘文竹张婷刘婷艾陈晓明施红颖锦州医科大学中国人民解放军北部战区总医院研究生培养基地沈阳110003 中国人民解放军北部战区总医院妇产科沈阳110003

目的:联合母体因素和平均动脉压(MAP)评估英国胎儿医学基金会(FMF)算法对子痫前期(PE)的预测效能。方法:收集2021年8月至2021年12月于北部战区总医院妇产科门诊行NT彩超(孕11~13+6周)及住院孕妇1847例的临床资料,查阅并计算NT时平均动脉... 详细信息

目的:联合母体因素和平均动脉压(MAP)评估英国胎儿医学基金会(FMF)算法对子痫前期(PE)的预测效能。方法:收集2021年8月至2021年12月于北部战区总医院妇产科门诊行NT彩超(孕11~13+6周)及住院孕妇1847例的临床资料,查阅并计算NT时平均动脉压(MAP),通过FMF网站公开免费的PE风险计算器计算风险值。按妊娠结局是否患有PE分为未发病组、早发型PE组、晚发型PE组、早产型PE组、足月型PE组、全部PE组。绘制受试者工作特征曲线(ROC曲线),分别计算在固定假阳性率分别为5%、10%、15%、20%下该模型对PE及其不同亚型的灵敏度。与实际观测结果及我国《妊娠期高血压疾病诊治指南(2020)》、《ACOG指南(2018)》所建议的筛查结果进行比较,评价该模型的预测效能。结果:1847例妊娠孕妇中发生PE者112例(6.1%),其中早发型29例(1.6%),晚发型83例(4.4%),早产型PE 35例(1.9%),足月型PE 77例(4.1%)。母体因素+MAP较单一母体因素对PE的预测效果更好,ROC曲线下面积(AUC)为0.847,固定假阳性率分别为5%、10%、15%、20%下的灵敏度分别为45.50%、61.60%、70.50%、78.60%。其中对早产型PE的预测效能最佳,AUC为0.881,固定假阳性率分别为5%、10%、15%、20%下的灵敏度分别为51.40%、62.90%、74.30%、80.00%。根据我国《妊娠期高血压疾病诊治指南(2020)》、《ACOG指南(2018)》预测PE的灵敏度分别为8.04%(9/112)、56.25%(63/112)。在相同人群下,联合母体因素及MAP预测全部PE及早产型PE的灵敏度分别为77.68%(87/112)、85.71%(30/35),较各大指南对PE的预测效果明显升高。结论:联合母体因素和MAP应用FMF竞争风险模型对PE患病有较好的预测效能,且对早产型PE的预测效能最好,优于单一母体因素及各大指南。在资源欠缺的地区或医院可选择联合母体因素和MAP来预测PE。

关键词：子痫前期预测模型竞争风险模型英国胎儿基金会算法平均动脉压

DNA cytosine methylation dynamics and functional roles in horticultural crops

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Horticulture Research 2023年第10期10卷 273-283页

作者： Peipei liu Ruie liu Yaping Xu caixi Zhang Qingfeng Niu Zhaobo Lang National Engineering Laboratory of Crop Stress Resistance Breeding School of Life SciencesAnhui Agricultural UniversityHefei230036China School of Agriculture and Biology Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Center for Plant Stress Biology National Key Laboratory of Plant Molecular GeneticsCenter for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghai 201602China Institute of Advanced Biotechnology School of Life SciencesSouthern University of Science and TechnologyShenzhen 518055China

Methylation of cytosine is a conserved epigenetic modification that maintains the dynamic balance of methylation in plants under the regulation of methyltransferases and *** recent years,the study of DNA methylation in regulating the growth and development of plants and animals has become a key area of *** review describes the regulatory mechanisms of DNA cytosine methylation in *** summarizes studies on epigenetic modifications of DNA methylation in fruit ripening,development,senescence,plant height,organ size,and under biotic and abiotic stresses in horticultural *** review provides a theoretical basis for understanding the mechanisms of DNA methylation and their relevance to breeding,genetic improvement,research,innovation,and exploitation of new cultivars of horticultural crops.

关键词： crops maintain breeding