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微沟槽织构设计对PDMS表面黏-滑摩擦学行为的影响 被引量:2
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作者 施文斌 肖汉 +4 位作者 崔坤杰 王涛 时礼平 吴玉国 李蒙 《摩擦学学报(中英文)》 EI CAS CSCD 北大核心 2024年第1期70-77,共8页
“黏-滑”现象是软材料表面摩擦学行为典型的特征,易诱发机械系统的振动与噪音等问题.本文中采用激光加工技术在PDMS(Polydimethylsiloxane,聚二甲基硅氧烷)表面加工了沟槽状织构阵列,研究不同参数织构设计对软材料表面“黏-滑”摩擦行... “黏-滑”现象是软材料表面摩擦学行为典型的特征,易诱发机械系统的振动与噪音等问题.本文中采用激光加工技术在PDMS(Polydimethylsiloxane,聚二甲基硅氧烷)表面加工了沟槽状织构阵列,研究不同参数织构设计对软材料表面“黏-滑”摩擦行为的影响.结果表明沟槽织构可以有效抑制软材料表面“黏-滑”行为,降低界面摩擦阻力,但沟槽的作用效能依赖于其倾斜角设计.此外,界面滑动速度和沟槽织构宽度也是影响表面摩擦学行为的主要因素. 展开更多
关键词 黏-滑”行为 软材料 摩擦学 弹性 表面织构
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单晶Cu表面黏-滑效应的分子动力学模拟 被引量:3
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作者 程东 严志军 严立 《金属学报》 SCIE EI CAS CSCD 北大核心 2006年第11期1149-1152,共4页
运用分子动力学方法模拟了Cu单晶在微摩擦过程中的黏-滑效应.模拟结果表明:在原子尺度,摩擦表面的原子排列较规则,摩擦力曲线为大小锯齿的周期变化.这种黏-滑效应可以解释为位错机制,即摩擦表面间位错的产生与消失的过程.大小锯齿的... 运用分子动力学方法模拟了Cu单晶在微摩擦过程中的黏-滑效应.模拟结果表明:在原子尺度,摩擦表面的原子排列较规则,摩擦力曲线为大小锯齿的周期变化.这种黏-滑效应可以解释为位错机制,即摩擦表面间位错的产生与消失的过程.大小锯齿的峰值受载荷、滑动速度、接触面两侧的晶格常数及品格位向差等多个因素的影响.载荷越大,针尖滑动时移动的原子数量越多,接触面两侧的原子排列越不规则,则小锯齿的峰值越小,并随着载荷的增大而逐渐消失.摩擦力曲线中的小锯齿峰值与滑动速度呈线性关系.不同材料的接触面和不同滑动方向的黏-滑现象并不相同.摩擦力曲线的变化周期取决于滑动过程中基体沿滑动方向的晶格常数. 展开更多
关键词 Cu单晶 黏-滑效应 分子动力学模拟 微观干摩擦
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可公度自组装膜原子尺度黏-滑摩擦特性研究
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作者 张涛 张靖 +1 位作者 王慧 胡元中 《自然科学进展》 北大核心 2002年第9期1005-1008,共4页
使用经典分子动力学模拟的方法研究了金(111)上自组装膜的挤压和摩擦过程,计算结果表明摩擦力对应于表面的几何结构而周期变化,膜中不同单体粒子(头基和尾基)以有序的黏滑和跳跃的方式运动,静止下层膜的头基都有2~3个准稳态位置,黏滞... 使用经典分子动力学模拟的方法研究了金(111)上自组装膜的挤压和摩擦过程,计算结果表明摩擦力对应于表面的几何结构而周期变化,膜中不同单体粒子(头基和尾基)以有序的黏滑和跳跃的方式运动,静止下层膜的头基都有2~3个准稳态位置,黏滞阶段头基在其中一个准稳态处振荡,两层相对滑动膜的尾基一起被拖动,而在滑动阶段头基同时跳动到一个新的准稳态,上层膜的尾基相对下层向前跳动晶格常数的一半,由此建立起摩擦过程中自组装膜链分子完整的运动模式并和Tomlinson模型所预测的进行了比较。 展开更多
关键词 原子尺度 黏-滑摩擦特性 分子动力学模拟 自组装膜 动摩擦 十二烷硫醇/金 摩擦机理 表面构形
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Cysteamine increases expression and activity of H^1-K^+-ATPase of gastric mucosal cells in weaning piglets 被引量:3
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作者 Zhi-Min Shi Gai-Mei Du Xi-Hui Wei Lei Zhang Jie Chen Ru-Qian Zhao 《World Journal of Gastroenterology》 SCIE CAS CSCD 2005年第42期6707-6712,共6页
AIM: To determine the in vivo andin vivo effects of cysteamine (CS) on expression and activity of H+-K+-ATPase of gastric mucosal cells in weaning piglets.METHODS: Eighteen litters of newborn Xinhuai piglets were empl... AIM: To determine the in vivo andin vivo effects of cysteamine (CS) on expression and activity of H+-K+-ATPase of gastric mucosal cells in weaning piglets.METHODS: Eighteen litters of newborn Xinhuai piglets were employed in the in vivo experiment and allocated to control and treatment groups. From 12 d of age (D12), piglets in control group were fed basal diet, while the treatment group received basal diet supplemented with 120 mg/kg CS. Piglets were weaned on D35 in both groups. Six piglets from each group (n = 6) were slaughtered on D28 (one week before weaning), D35(weaning), D36.5, D38, D42, and D45 (36 h, 72 h,one week and 10 d after weaning), respectively. Semiquantitative RT-PCR was performed todetermine the levels of H+-K+-ATPase mRNA in gastric mucosa. H+-K+-ATPase activity in gastric mucosa homogenate was also determined. Gastric mucosal epithelial cells from piglets through primary cultures were used to further elucidate the effect of CS on expression and activity of H+-K+-ATPase in vivo. Cells were treated for 20 h with 0.001,0.01, and 0.1 mg/mL of CS (n = 4), respectively. The mRNA expression of H+-K+-ATPase and somatostatin (SS)as well as the H+-K+-ATPase activity were determined.RESULTS: in vivo, both mRNA expression and activity of H+-K+-ATPase in gastric mucosa of control group exhibited a trend to increase from D28 to D45, reaching a peak on D45, but did not show significant age differences. Furthermore, neither the mRNA expression nor the activity of H+-K+-ATPase was affected significantly by weaning. CS increased the mRNA expression of H+-K+-ATPase by 73%, 53%, 30% and 39% on D28(P = 0.014), D35 (P = 0.017), D42 (P = 0.013) and D45(P = 0.046), respectively. In accordance with the mRNA expression, H+-K+-ATPase activities were significantly higher in treatment group than in control group on D35(P = 0.043) and D45 (P = 0.040). In vivo, CS exhibited a dose-dependent effect on mRNA expression and activity of H+-K+-ATPase. Both H+-K+-ATPase mRNA expression and activity in gastric mucosal epithelial cells were significantly elevated after 20 h of exposure to the moderate (H+-K+-ATPase expression: P=0.03; H+-K+-ATPase activity: P = 0.014) and high concentrations (H+-K+-ATPase expression: P=0.017; H+-K+-ATPase activity:P = 0.022) of CS. Significant increases in SS mRNA expression were observed to accompany the elevation of H+-K+-ATPase expression and activity induced by the moderate (P = 0.024) and high concentrations (P = 0.022) of CS. Low concentration of CS exerted no effects either on expression and activity of H+-K+-ATPase or on SS mRNA expression in cultured gastric mucosal epithelial cells.CONCLUSION: No significant changes are observed in mRNA expression and activity of H+-K+-ATPase in gastric mucosa of piglets around weaning from D28 to D45. CS increases expression and activity of gastric H+-K+-ATPase in vivo and in vivo. SS is involved in mediating the effect of CS on gastric H+-K+-ATPase expression and activity in weaning piglets. 展开更多
关键词 CYSTEAMINE Weaning piglets H^+ -K^+-ATPase Gastric mucosal cells SOMATOSTATIN
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Magnetohydrodynamic flow and heat transfer impact on ZnO-SAE50 nanolubricant flow over an inclined rotating disk 被引量:3
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作者 NAYAK M K MEHMOOD Rashid +2 位作者 MAKINDE O D MAHIAN O CHAMKHA Ali J 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第5期1146-1160,共15页
The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic f... The present article has been fine-tuned with the investigation of mixed convection Darcy-Forchheimer flow of ZnO-SAE50 oil nanolubricant over an inclined rotating disk under the influence of uniform applied magnetic field applied to various industries.The current study has been enriched with additional consideration of slip flow,thermal radiation,viscous dissipation,Joulian dissipation and internal heating.In view of augmentation of thermal conductivity of nanolubricant,a new micro-nano-convection model namely Patel model has been invoked.The specialty of this model involves the effects of specific surface area and nano-convection due to Brownian motion of nanoparticles,kinetic theory based micro-convection,liquid layering and particle concentration.Suitably transformed governing equations have been solved numerically by using Runge-Kutta-Fehlberg scheme.An analysis of the present study has shown that applied magnetic field,porosity of the medium,velocity slip and inertia coefficient account for the slowing down of radial as well as tangential flow of ZnO-SAE50 oil nanolubricant,thereby leading to an improvement in velocity and thermal boundary layers. 展开更多
关键词 ZnO-SAE50 nanofluid Darcy-Forchheimer MHD flow thermal radiation velocity slip viscous dissipation internal heating
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酚醛树脂基摩擦材料摩擦振动演化行为规律与机制研究
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作者 侯鑫 杜军华 +6 位作者 魏鹏 李京洋 邬志蹦 李威 曹辉 白鹏鹏 田煜 《摩擦学学报(中英文)》 EI CAS CSCD 北大核心 2024年第10期1334-1344,共11页
酚醛树脂基摩擦材料与金属组成的摩擦副经长时间服役容易出现剧烈摩擦振动和辐射高频噪声,可能导致设备停机甚至损坏.本文中针对酚醛树脂基摩擦材料/球墨铸铁摩擦副在往复摩擦试验中的摩擦振动行为演化开展了系统研究.为不干扰摩擦系统... 酚醛树脂基摩擦材料与金属组成的摩擦副经长时间服役容易出现剧烈摩擦振动和辐射高频噪声,可能导致设备停机甚至损坏.本文中针对酚醛树脂基摩擦材料/球墨铸铁摩擦副在往复摩擦试验中的摩擦振动行为演化开展了系统研究.为不干扰摩擦系统,采用了激光多普勒测速仪对摩擦振动进行非接触式高精度测量.试验过程中摩擦系统逐步出现80和800 Hz的振动,与其固有频率重合.通过对周期性摩擦力、振动数据、磨损表面形貌和速度依赖性的综合分析,提出摩擦过程中的“黏-滑”行为是诱导摩擦振动及噪声产生和演化的关键因素.伴随“黏-滑”行为的摩擦功和弹性能变化以及界面间由材料黏着和脱附等行为导致的摩擦力波动分别是诱导摩擦系统产生80 Hz低频振动和800 Hz高频自激振动的主要原因.磨损过程中的材料转移和界面间磨粒堆积会导致高频振动能量逐步增加.本研究中通过揭示酚醛树脂基摩擦材料摩擦振动的产生机理和演化规律,为低噪声摩擦系统界面设计提供了理论参考. 展开更多
关键词 摩擦振动 噪声 酚醛树脂 黏-滑 材料转移
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Shear mechanical properties and frictional sliding responses of rough joint surfaces under dynamic normal displacement conditions
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作者 ZHU Qiang YIN Qian +9 位作者 TAO Zhi-gang HE Man-chao ZHENG Bo-wen JING Hong-wen REN Shu-lin ZHANG Qiang MENG Bo BAI Dong-feng WU Sai-sai WU Jiang-yu 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2393-2410,共18页
A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating... A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating geological disasters.This study conducted shear experiments on rough rock joints under displacement-controlled dynamic normal loads,investigating the shear behaviors of joints across varying initial normal loads,normal loading frequencies,and normal loading amplitudes.Experimental results showed that the peak/valley shear force values increased with initial normal loads and normal loading frequencies but showed an initial increase followed by a decrease with normal loading amplitudes.Dynamic normal loading can either increase or decrease shear strength,while this study demonstrates that higher frequencies lead to enhanced friction.Increased initial normal loading and normal loading frequency result in a gradual decrease in joint roughness coefficient(JRC)values of joint surfaces after shearing.Positive correlations existed between frictional energy dissipation and peak shear forces,while post-shear joint surface roughness exhibited a negative correlation with peak shear forces through linear regression analysis.This study contributes to a better understanding of the sliding responses and shear mechanical characteristics of rock joints under dynamic disturbances. 展开更多
关键词 dynamic normal displacement shear strength variations phase lag phenomenon STICK-SLIP
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机械系统中摩擦颤振机理的非线性分析 被引量:10
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作者 黄毅 王太勇 +1 位作者 张莹 蒋永翔 《中国机械工程》 EI CAS CSCD 北大核心 2008年第14期1677-1680,共4页
对一类摩擦颤振中具有代表性的双质体—传输带干摩擦系统的平衡点进行了稳定性分析,利用平均法求得系统纯滑动状态下的近似解析解,并结合数值方法揭示系统的非线性动力学现象,讨论了摩擦颤振的产生机理。通过分析可知,在传输带速度减小... 对一类摩擦颤振中具有代表性的双质体—传输带干摩擦系统的平衡点进行了稳定性分析,利用平均法求得系统纯滑动状态下的近似解析解,并结合数值方法揭示系统的非线性动力学现象,讨论了摩擦颤振的产生机理。通过分析可知,在传输带速度减小的过程中,系统的静平衡状态失稳,出现纯滑动和黏滞-滑动形式的摩擦颤振现象。 展开更多
关键词 颤振 干摩擦 稳定性 黏-滑振动 非线性振动
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HDPE及其共混物的挤出压力振荡现象 被引量:6
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作者 李鹏 慕晶霞 +2 位作者 张娜 安鹏 吴其晔 《合成树脂及塑料》 CAS 北大核心 2006年第2期56-60,共5页
采用恒速型双毛细管流变仪研究高密度聚乙烯及其共混物的压力振荡现象,测量了压力振荡的振幅及频率,计算了熔体在管壁的滑移速率和临界外推滑移长度。结果表明,发生压力振荡时,熔体与毛细管壁的界面出现“时黏时滑”转变。黏界面时,挤... 采用恒速型双毛细管流变仪研究高密度聚乙烯及其共混物的压力振荡现象,测量了压力振荡的振幅及频率,计算了熔体在管壁的滑移速率和临界外推滑移长度。结果表明,发生压力振荡时,熔体与毛细管壁的界面出现“时黏时滑”转变。黏界面时,挤出物表面出现“鲨鱼皮”现象;滑界面时,挤出物表面粗糙,类似于无规破裂。随剪切速率的增加,压力振荡的振幅减小,而滑移速率、临界外推滑移长度及振荡频率均有提高。升高挤出温度和采用共混改性都可抑制压力振荡现象。 展开更多
关键词 高密度聚乙烯 挤出压力振荡 共混 黏-滑转变
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刹车系统摩擦自激振动的数值研究 被引量:7
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作者 李博 丁千 陈艳 《科技导报》 CAS CSCD 2007年第23期28-32,共5页
建立了刹车系统的三自由度动力学方程,采用LuGre模型计算摩擦块、盘之间的摩擦力。通过数值模拟,揭示非内共振摩擦块的复杂动力学行为。研究表明,随着摩擦盘速度减小,切向静平衡状态失稳,依次出现完全滑动和非完全黏滞-滑动的干摩擦自... 建立了刹车系统的三自由度动力学方程,采用LuGre模型计算摩擦块、盘之间的摩擦力。通过数值模拟,揭示非内共振摩擦块的复杂动力学行为。研究表明,随着摩擦盘速度减小,切向静平衡状态失稳,依次出现完全滑动和非完全黏滞-滑动的干摩擦自激振动现象。当黏性摩擦系数非常大时,会导致带有非完全黏滞特征的混沌运动。扭转运动的非完全黏滞自激振动中,包含了速度快速抖动现象;而切向和扭转运动是导致低、高频噪声的原因。 展开更多
关键词 刹车系统 干摩擦 自激振动 黏-滑振动
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纳米尺度摩擦过程的分子动力学模拟 被引量:2
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作者 刘小明 由小川 +1 位作者 柳占立 庄茁 《金属学报》 SCIE EI CAS CSCD 北大核心 2008年第9期1025-1030,共6页
利用分子动力学方法模拟了刚性金刚石压头在Ni单晶体上的滑动过程,讨沦了压入深度对摩擦力的影响(压入深度对滑动过程中压头下方的微结构演化(能否发射位错环)有很大影响).结合摩擦过程中的塑性行为和能量耗散机制,解释了产生摩擦力锯... 利用分子动力学方法模拟了刚性金刚石压头在Ni单晶体上的滑动过程,讨沦了压入深度对摩擦力的影响(压入深度对滑动过程中压头下方的微结构演化(能否发射位错环)有很大影响).结合摩擦过程中的塑性行为和能量耗散机制,解释了产生摩擦力锯齿形曲线的原因,证实了位错的形核及湮灭是黏一滑机制的原因之一.不同滑动速度对摩擦力影响的模拟表明,压头的滑动速度决定了压头下方位错环的运动和演化形式:在高速滑动下,形成的位错环依次沿着滑移面很快向Ni单晶基体内扩展;在低速滑动下,压头下方产生的位错环互相发生作用,在材料的亚表面形成较低能量的大位错环,由此产生的塑性变形主要集中在材料的亚表面. 展开更多
关键词 纳米尺度 摩擦 分子动力学 黏-滑机制 位错环
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Effect of variable liquid properties on peristaltic transport of Rabinowitsch liquid in convectively heated complaint porous channel 被引量:1
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作者 Hanumesh VAIDYA Rajashekhar CHOUDHARI +1 位作者 Manjunatha GUDEKOTE Kerehalli Vinayaka PRASAD 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第5期1116-1132,共17页
The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer.The effect of inclination on t... The present paper emphasizes the peristaltic mechanism of Rabinowitsch liquid in a complaint porous channel under the influence of variable liquid properties and convective heat transfer.The effect of inclination on the complaint channel walls has been taken into account.The viscosity of the liquid varies across the thickness of the complaint channel,whereas,thermal conductivity varies concerning temperature.The nonlinear governing equations are solved by using perturbation technique under the long wavelength and small Reynold’s number approximations.The expressions for axial velocity,temperature,the coefficient of heat transfer and streamlines are obtained and analyzed graphically.The above said physiological phenomena are investigated for a specific set of relevant parameters on dilatant,Newtonian and pseudoplastic fluid models.The results presented here shows that the presence of variable viscosity,porous parameter and slip parameter significantly affects the flow quantities of dilatant,Newtonian and pseudoplastic fluid models.The investigation further reveals that an increase in the value of variable viscosity and porous parameters enhances the occurrence of trapping phenomenon.Moreover,the size of trapped bolus can be eliminated with suitably adjusting the angle of inclination parameter. 展开更多
关键词 Rabinowitsch liquid Biot number porous parameter thermal conductivity variable viscosity velocity slip
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Enhancing performance of soil using lime and precluding landslide in Benin(West Africa)
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作者 Quirin Engelbert Ayeditan ALAYE LING Xian-zhang +3 位作者 Yvette Sèdjro KIKI TANKPINOU Marx Ferdinand AHLINHAN LUO Jun Michel Hadilou ALAYE 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第11期3066-3086,共21页
The past decade has been characterized by the development of infrastructure in the main cities in West Africa.This requires more comprehensive studies of geotechnical properties of the soil in the region with an aim o... The past decade has been characterized by the development of infrastructure in the main cities in West Africa.This requires more comprehensive studies of geotechnical properties of the soil in the region with an aim of creating sustainable development.This paper examined the performance of the soil in Benin(West Africa).In this research,three objectives have been adopted in-depth on the performance characteristics of West Africans soil and aim to(i)accessing characteristics of soil types in the region;(ii)assessing the performance of these soils with 2%,3%and 5%of lime and(iii)characterizing landslide to evaluate the damage and potential instability.The methods used to examine these objectives are experimental tests according to standard French test.The particle size test,Proctor test,and Atterberg limits test which are physical tests and the mechanical tests such as dynamic penetration test,direct shear test,and oedometer test,were used to assess the first objective.The Proctor test and California bearing ratio test were examined for the second objective and geological,environmental,social and safety study of the river bank slide were evaluated for the third objective.This paper firstly reveals the unstable and stable areas in southern Benin(West Africa)with the presence of clays soil and gives an equation for predicting the unstable and stable area,and secondly shows that the proportion of percentage lime leading to the best performances varying between 2%and 3%.Finally,this paper shows that the sliding of a bank could be the consequence of the sudden receding water recorded in a valley. 展开更多
关键词 soil characterization soil performance clay soil LIME LANDSLIDE
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Model for mucus transport in the airways due to air motion: Effect of slipperiness
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作者 Dipak Kumar Satpathi Kota Venkata Ratnamt Adepalli Ramu 《International Journal of Biomathematics》 2016年第5期171-183,共13页
In this paper, a circular three-layer flow model is proposed to study mucus transport in the airways due to air motion caused by mild forced expiration or mild coughing. Mucus is represented by four-parameter viscoela... In this paper, a circular three-layer flow model is proposed to study mucus transport in the airways due to air motion caused by mild forced expiration or mild coughing. Mucus is represented by four-parameter viscoelastic fluid, a combination of Maxwell and Voigt elements, whereas air and serous fluid are taken as Newtonian fluids (incompressible). The pressure gradient generated in the fluid layers is assumed to be given by a time- dependent function representing mild forced expiration or mild cough in the airways causing laminar flow. The effect of slip velocity at the mucus-serous interface caused by the presence of surfactant and at the top surface caused by immotile cilia are Mso taken into account. The roles of rheological properties of mucus on its transport are studied. The effect of serous fluid and its viscosity on mucus transport is also considered. 展开更多
关键词 VISCOELASTIC Maxwell fluid MUCUS serous layer SURFACTANT
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