Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavio...Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavior in the microchannels/pores has attracted many researchers'attention due to the advantages of light such as non-contact stimulation,tunable excitation,high spatial and temporal resolution.With efforts,great achievements and progresses have been achieved for photochemical effect driven microscale flow control,including fluid pumping,flow rate control,and fluid mixing,etc.In this review,we discuss the responsive mechanisms of photochemical effect driven fluid behavior control at the microscale.We also give a comprehensive review on the latest research progresses in photochemical effect controlled microfluid behaviors.Besides,prospective opportunities for the future development of light control of microscale flow are provided to attract scientific interest for the fast development and applications of various microchannel/pore systems.展开更多
The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic e...The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.展开更多
In the paper, we study a compressible two-fluid model in ℝ3, where γ±>1. The pressure of the two fluids is equal. Different from previous research, we consider that viscosity coefficient both μand λare func...In the paper, we study a compressible two-fluid model in ℝ3, where γ±>1. The pressure of the two fluids is equal. Different from previous research, we consider that viscosity coefficient both μand λare functions of density. The global well-posedness of the three-dimensional compressible two-phase flow model is an open problem due to its dissipative, nonlinear structure. In the paper, setting m±=M±and Z=P−P¯, by exploiting the dissipation structure, we obtain energy estimates for (Z,w,n)and its derivatives, then we obtain the time decay rates for (Z,w,n). So we derive global well-posedness and large time behavior to the three dimensional compressible two-fluid model.展开更多
目的分析神经梅毒(neurosyphilis,NS)患者的临床资料,探讨影响其日常生活活动能力(activity of daily living,ADL)的因素。方法对90例NS患者的临床资料进行回顾性分析,使用巴塞尔指数(Barthel index,BI)评估患者入院时ADL,将患者分为无...目的分析神经梅毒(neurosyphilis,NS)患者的临床资料,探讨影响其日常生活活动能力(activity of daily living,ADL)的因素。方法对90例NS患者的临床资料进行回顾性分析,使用巴塞尔指数(Barthel index,BI)评估患者入院时ADL,将患者分为无需依赖组、轻度依赖组和中重度依赖组,通过比较分析和多因素线性回归分析,探讨ADL的影响因素。采用受试者操作特征(receiver operating characteristic,ROC)曲线评估临床指标对出院时ADL恢复不良(BI评分≤60分)患者的预测效能。结果90例NS患者,年龄(54.17±12.45)岁,男性70例(77.78%)。临床表现中精神行为异常(44.44%)最为常见,其次为肢体感觉或运动障碍(25.56%)、构音障碍(16.67%)。根据BI评分分组,无需依赖组41例(45.6%),轻度依赖组31例(34.4%),中重度依赖组18例(20.0%)。3组比较,中性粒细胞/淋巴细胞比值(neutrophil-to-lymphocyte ratio,NLR)逐渐增高[2.80(1.97,4.73)vs.3.80(2.28,4.89)vs.5.37(3.76,7.20)],中重度依赖组分别高于无需依赖组及轻度依赖组(P<0.05);脑脊液蛋白浓度逐渐增多[427(341,644)mg/L vs.553(425,830)mg/L vs.933(641,1706.5)mg/L],两两比较均有统计学差异(P<0.05)。多因素线性回归分析显示,NLR(β=-0.242,P=0.018)和脑脊液蛋白浓度(β=-0.461,P<0.001)与入院时的ADL呈负相关。脑脊液蛋白浓度预测出院时ADL恢复不良患者的曲线下面积(area under the curve,AUC)为0.806(95%CI:0.708~0.883,P<0.001),最佳截断值为620 mg/L,敏感性和特异性分别为86.7%和69.4%。结论NS患者主要临床表现为精神行为异常,NLR、脑脊液蛋白浓度增高与ADL降低相关联,早期积极干预炎症反应及脑脊液蛋白异常可能为改善患者预后提供新思路。展开更多
Cavitation has a significant e ect on the flow fields and structural behaviors of a centrifugal pump. In this study, the unsteady flow and structural behaviors of a centrifugal pump are investigated numerically under ...Cavitation has a significant e ect on the flow fields and structural behaviors of a centrifugal pump. In this study, the unsteady flow and structural behaviors of a centrifugal pump are investigated numerically under di erent cavitation conditions. A strong two-way coupling fluid-structure interaction simulation is applied to obtain interior views of the e ects of cavitating bubbles on the flow and structural dynamics of a pump. The renormalization-group k-ε turbulence model and the Zwart–Gerbe–Belamri cavitation model are solved for the fluid side, while a transient structural dynamic analysis is employed for the structure side. The di erent cavitation states are mapped in the head-net positive suction head(H-NPSH) curves and flow field features inside the impeller are fully revealed. Results indicate that cavitating bubbles grow and expand rapidly with decreasing NPSH. In addition, the pressure fluctuations, both in the impeller and volute, are quantitatively analyzed and associated with the cavitation states. It is shown that influence of the cavitation on the flow field is critical, specifically in the super-cavitation state. The e ect of cavitation on the unsteady radial force and blade loads is also discussed. The results indicate that the averaged radial force increased from 8.5 N to 54.4 N in the transition progress from an onset cavitation state to a super-cavitation state. Furthermore, the structural behaviors, including blade deformation, stress, and natural frequencies, corresponding to the cavitation states are discussed. A large volume of cavitating bubbles weakens the fluid forces on the blade and decreases the natural frequencies of the rotor system. This study could enhance the understanding of the e ects of cavitation on pump flow and structural behaviors.展开更多
To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines...To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.展开更多
As demonstrated by a great amount of geologic and experimental evidences, RE of rock systems may be mobilized during fluid-rock interaction when solutions are rich in F -, Cl -, CO 3 2-, HCO 3 -, CO 2, HPO 4...As demonstrated by a great amount of geologic and experimental evidences, RE of rock systems may be mobilized during fluid-rock interaction when solutions are rich in F -, Cl -, CO 3 2-, HCO 3 -, CO 2, HPO 4 2-, HS -, S 2-, SO 4 2-, though little has been known about the mobilizing mechanism of these anions or ligands. The fractionation of RE resulted from hydrothermal alterations, i. e., fluid-rock interactions, are distinctive. One set of field data implies the preferential mobility of the LRE, while another set of field observations demonstrates the dominant mobilization of the HRE, and some theoretical prediction is not consistent with the field evidence. The Eu anomalies caused by fluid-rock interaction are complex and compelling explanation is not available due to inadequate experimental approaches. To know the exact behavior of RE during fluid-rock interaction and to solve the contradiction between some theoretical predictions and field observations, the following works remain to be done: (1) experimental investigations of RE mobility and fractionation as a function of fluid chemistry, e.g., the activity of F -, Cl -, CO 3 2-, HCO 3 -, CO 2, HPO 4 2-, HS -, S 2-, SO 4 2-, etc.; (2) experimental determination of RE mobility and fractionation as a function of T, P, pH, E h and water/rock ratios; (3) investigation of the mechanism and the controlling factors of RE partitioning between hydrothermal minerals and fluids. It was demonstrated that RE mobility is a potentially useful method for exploration.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52025132,21975209 and 22005255)the National Key R&D Program of China(No.2018YFA0209500)+1 种基金the Overseas Expertise Introduction Project for Discipline Innovation(111Project,No.B16029)the Fundamental Research Funds for the Central Universities(No.20720190037)。
文摘Manipulating the fluid transport in the microscale pores and channels is playing a paramount role in the realization of the versatile functions of microfluidics.In recent years,using light to control the fluid behavior in the microchannels/pores has attracted many researchers'attention due to the advantages of light such as non-contact stimulation,tunable excitation,high spatial and temporal resolution.With efforts,great achievements and progresses have been achieved for photochemical effect driven microscale flow control,including fluid pumping,flow rate control,and fluid mixing,etc.In this review,we discuss the responsive mechanisms of photochemical effect driven fluid behavior control at the microscale.We also give a comprehensive review on the latest research progresses in photochemical effect controlled microfluid behaviors.Besides,prospective opportunities for the future development of light control of microscale flow are provided to attract scientific interest for the fast development and applications of various microchannel/pore systems.
基金supported by the National Natural Science Foundation of China(52304021,52104022,52204031)the Natural Science Foundation of Sichuan Province(2022NSFSC0205,2024NSFSC0201,2023NSFSC0947)the National Science and Technology Major Projects of China(2017ZX05049006-010).
文摘The global energy demand is increasing rapidly,and it is imperative to develop shale hydrocarbon re-sources vigorously.The prerequisite for enhancing the exploitation efficiency of shale reservoirs is the systematic elucidation of the occurrence characteristics,flow behavior,and enhanced oil recovery(EOR)mechanisms of shale oil within commonly developed nanopores.Molecular dynamics(MD)technique can simulate the occurrence,flow,and extraction processes of shale oil at the nanoscale,and then quantitatively characterize various fluid properties,flow characteristics,and action mechanisms under different reservoir conditions by calculating and analyzing a series of MD parameters.However,the existing review on the application of MD simulation in shale oil reservoirs is not systematic enough and lacks a summary of technical challenges and solutions.Therefore,recent MD studies on shale oil res-ervoirs were summarized and analyzed.Firstly,the applicability of force fields and ensembles of MD in shale reservoirs with different reservoir conditions and fluid properties was discussed.Subsequently,the calculation methods and application examples of MD parameters characterizing various properties of fluids at the microscale were summarized.Then,the application of MD simulation in the study of shale oil occurrence characteristics,flow behavior,and EOR mechanisms was reviewed,along with the elucidation of corresponding micro-mechanisms.Moreover,influencing factors of pore structure,wall properties,reservoir conditions,fluid components,injection/production parameters,formation water,and inorganic salt ions were analyzed,and some new conclusions were obtained.Finally,the main challenges associated with the application of MD simulations to shale oil reservoirs were discussed,and reasonable prospects for future MD research directions were proposed.The purpose of this review is to provide theoretical basis and methodological support for applying MD simulation to study shale oil reservoirs.
文摘In the paper, we study a compressible two-fluid model in ℝ3, where γ±>1. The pressure of the two fluids is equal. Different from previous research, we consider that viscosity coefficient both μand λare functions of density. The global well-posedness of the three-dimensional compressible two-phase flow model is an open problem due to its dissipative, nonlinear structure. In the paper, setting m±=M±and Z=P−P¯, by exploiting the dissipation structure, we obtain energy estimates for (Z,w,n)and its derivatives, then we obtain the time decay rates for (Z,w,n). So we derive global well-posedness and large time behavior to the three dimensional compressible two-fluid model.
文摘目的分析神经梅毒(neurosyphilis,NS)患者的临床资料,探讨影响其日常生活活动能力(activity of daily living,ADL)的因素。方法对90例NS患者的临床资料进行回顾性分析,使用巴塞尔指数(Barthel index,BI)评估患者入院时ADL,将患者分为无需依赖组、轻度依赖组和中重度依赖组,通过比较分析和多因素线性回归分析,探讨ADL的影响因素。采用受试者操作特征(receiver operating characteristic,ROC)曲线评估临床指标对出院时ADL恢复不良(BI评分≤60分)患者的预测效能。结果90例NS患者,年龄(54.17±12.45)岁,男性70例(77.78%)。临床表现中精神行为异常(44.44%)最为常见,其次为肢体感觉或运动障碍(25.56%)、构音障碍(16.67%)。根据BI评分分组,无需依赖组41例(45.6%),轻度依赖组31例(34.4%),中重度依赖组18例(20.0%)。3组比较,中性粒细胞/淋巴细胞比值(neutrophil-to-lymphocyte ratio,NLR)逐渐增高[2.80(1.97,4.73)vs.3.80(2.28,4.89)vs.5.37(3.76,7.20)],中重度依赖组分别高于无需依赖组及轻度依赖组(P<0.05);脑脊液蛋白浓度逐渐增多[427(341,644)mg/L vs.553(425,830)mg/L vs.933(641,1706.5)mg/L],两两比较均有统计学差异(P<0.05)。多因素线性回归分析显示,NLR(β=-0.242,P=0.018)和脑脊液蛋白浓度(β=-0.461,P<0.001)与入院时的ADL呈负相关。脑脊液蛋白浓度预测出院时ADL恢复不良患者的曲线下面积(area under the curve,AUC)为0.806(95%CI:0.708~0.883,P<0.001),最佳截断值为620 mg/L,敏感性和特异性分别为86.7%和69.4%。结论NS患者主要临床表现为精神行为异常,NLR、脑脊液蛋白浓度增高与ADL降低相关联,早期积极干预炎症反应及脑脊液蛋白异常可能为改善患者预后提供新思路。
基金Supported by National Natural Science Foundation of China(Grant Nos.51609212,51606167)China Postdoctoral Science Foundation(Grant No.2016M590546)Zhejiang Provincial Natural Science Foundation(Grant No.2016C31043)
文摘Cavitation has a significant e ect on the flow fields and structural behaviors of a centrifugal pump. In this study, the unsteady flow and structural behaviors of a centrifugal pump are investigated numerically under di erent cavitation conditions. A strong two-way coupling fluid-structure interaction simulation is applied to obtain interior views of the e ects of cavitating bubbles on the flow and structural dynamics of a pump. The renormalization-group k-ε turbulence model and the Zwart–Gerbe–Belamri cavitation model are solved for the fluid side, while a transient structural dynamic analysis is employed for the structure side. The di erent cavitation states are mapped in the head-net positive suction head(H-NPSH) curves and flow field features inside the impeller are fully revealed. Results indicate that cavitating bubbles grow and expand rapidly with decreasing NPSH. In addition, the pressure fluctuations, both in the impeller and volute, are quantitatively analyzed and associated with the cavitation states. It is shown that influence of the cavitation on the flow field is critical, specifically in the super-cavitation state. The e ect of cavitation on the unsteady radial force and blade loads is also discussed. The results indicate that the averaged radial force increased from 8.5 N to 54.4 N in the transition progress from an onset cavitation state to a super-cavitation state. Furthermore, the structural behaviors, including blade deformation, stress, and natural frequencies, corresponding to the cavitation states are discussed. A large volume of cavitating bubbles weakens the fluid forces on the blade and decreases the natural frequencies of the rotor system. This study could enhance the understanding of the e ects of cavitation on pump flow and structural behaviors.
文摘To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.
文摘As demonstrated by a great amount of geologic and experimental evidences, RE of rock systems may be mobilized during fluid-rock interaction when solutions are rich in F -, Cl -, CO 3 2-, HCO 3 -, CO 2, HPO 4 2-, HS -, S 2-, SO 4 2-, though little has been known about the mobilizing mechanism of these anions or ligands. The fractionation of RE resulted from hydrothermal alterations, i. e., fluid-rock interactions, are distinctive. One set of field data implies the preferential mobility of the LRE, while another set of field observations demonstrates the dominant mobilization of the HRE, and some theoretical prediction is not consistent with the field evidence. The Eu anomalies caused by fluid-rock interaction are complex and compelling explanation is not available due to inadequate experimental approaches. To know the exact behavior of RE during fluid-rock interaction and to solve the contradiction between some theoretical predictions and field observations, the following works remain to be done: (1) experimental investigations of RE mobility and fractionation as a function of fluid chemistry, e.g., the activity of F -, Cl -, CO 3 2-, HCO 3 -, CO 2, HPO 4 2-, HS -, S 2-, SO 4 2-, etc.; (2) experimental determination of RE mobility and fractionation as a function of T, P, pH, E h and water/rock ratios; (3) investigation of the mechanism and the controlling factors of RE partitioning between hydrothermal minerals and fluids. It was demonstrated that RE mobility is a potentially useful method for exploration.
