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Brownian Dynamics Simulation of Microstructures and Elongational Viscosities of Micellar Surfactant Solution

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Chinese Physics Letters 2008年第12期25卷 4469-4472页

作者：魏进家 kawaguchi yasuo 宇波李凤臣 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Department of Mechanical Engineering Faculty of Science and Technology Tokyo University of Science Noda Chiba 2788-510 Japan Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum (Beijing) Beijing 102249 School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001

Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine the micellar network structures in the surfactant solution. The micellar network is successfully simulated. It is formed at low elongation rates and destroyed by high elongation rates. The computed elongational viscosities show elongation- thinning characteristics. The relationship between the elongational viscosities and the mierostructure of the surfactant solution is revealed.

关键词： field emission molybdenum dioxide enhancement factor

Formation of Gel-Like Shear-Induced Structure with Dosing of Dilute Surfactant Solution and Its Effect on Turbulent Channel Flow

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Open Journal of Fluid Dynamics 2022年第3期12卷 249-262页

作者： Shumpei Hara Kazuki Ishii yasuo kawaguchi Department of Mechanical Engineering Doshisha University Kyoto Japan Department of Mechanical Engineering Tokyo University of Science Chiba Japan

A shear-induced structure (SIS) is formed under appropriate concentration and shear conditions in a surfactant micellar solution. In this study, we performed experiments of surfactant solution dosing in a fully developed two-dimensional turbulent channel flow from a sintered metallic wire mesh plate attached to a side wall. We investigated the behavior of the solution under the elongation during its passing through the wire mesh and under the strong shear due to the channel flow. It was confirmed that the dosed solution containing a laser dye was visualized by a laser sheet, and the accumulated gel from the wire mesh formed a layer and developed with time. Consequently, on dosing the dilute surfactant solution from the wire mesh, a gel-like SIS layer was formed, which majorly covered the wire mesh plate. The gel-like SIS layer on the wire mesh plate acted as a sticky solid and restricted the flow in the channel. This layer continued to grow while dosing, owing to which the pressure drop of the channel flow significantly increased. The gel-like SIS layer grew rapidly even in the turbulent flow and reached the equilibrium thickness. After the termination of the dosing, the gel layer collapsed gradually. In addition, the thickness of the gel-like SIS layer (indicating the strength indirectly) strongly depended on the surfactant concentration and the elongation rate in the wire mesh.

关键词： Turbulent Channel Flow Viscoelastic Fluid Gelation Scalar Transfer PIV/PLIF

Study on the Shear Effect on Dye Patches Diffused in Wall-Bounded Shear Flow

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Open Journal of Fluid Dynamics 2016年第4期6卷 438-452页

作者： Qianqian Shao Takahiro Tsukahara yasuo kawaguchi Department of Mechanical Engineering Tokyo University of Science Chiba Japan

This paper focuses on the high intensity filaments (dye patches) embedded in dye plumes in a wall-bounded shear flow, to investigate the shear effect on the dye patch distribution. Motivated by the widely concerned inverse estimation of the source location, we try extracting useful information to know the source location from down-stream dye patches. Accordingly, we changed the dye injection location at different distances from the wall and made observations at different downstream (diffusion) distances from the source. The orientation angle and roundness of dye patches were concerned to examine the shear effect and dye patch characteristics. To capture the dye plume images, a planar laser induced fluorescence (PLIF) technique was used. The orientation and roundness of each dye patch were calculated by least-square fitting. The statistics of both the orientation angle and the roundness were compared with those in homogeneous turbulent cases to reveal the shear effect. Different from uniformly-orientated dye patches in the homogeneous flow, larger occurrence probabilities with positive orientation angles of dye patches are observed in wall-bounded shear flow, in particular, when the injection location is near the wall. As with information extraction for the inverse estimation of source location, it is found that the orientation distribution of dye patches is independent of the diffusion distance, but related with the injection location from the wall. While for the homogeneous flow cases, a strong dependence on the diffusion distance is observed in the orientation distribution profiles. As for the roundness, similar aspects are found regarding the dependencies on the injection location in shear flow and on diffusion distance in homogeneous flow.

关键词： Dye Patch Image Processing Inverse Problem Least-Square Fitting Passive Scalar Shear Flow Source Estimation Point-Source Diffusion Wall Turbulence

Inverse Source Locating Method Based on Graphical Analysis of Dye Plume Images in a Turbulent Flow

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Open Journal of Fluid Dynamics 2016年第4期6卷 343-360页

作者： Qianqian Shao Daichi Sekine Takahiro Tsukahara yasuo kawaguchi Department of Mechanical Engineering Tokyo University of Science Chiba Japan

The inverse estimation of a source location of pollutant released into a turbulent flow is a probability problem instead of a deterministic one, as the turbulent flow is chaotic and irreversible. However, researches can be conducted to provide helpful instructions to the possible source location with corresponding uncertainty. This study aims to propose a method of inverse estimation of a passive-scalar source location. Experimental investigation of the dye plume characteristics released into a fully-developed turbulent flow is performed in a water channel. A planar laser-induced fluorescence (PLIF) technique is used to obtain two-dimensional images of spreading dye plumes at a bulk Reynolds number of 20,000. The distributions of high concentration areas in the PLIF images are chosen as features that characterize the traveling (diffusion) distance or time from the dye source. Graphical analysis is used to extract these high concentration areas. The procedure of graphical analysis has three steps: 1) binarization using a threshold to extract high concentration dye patches;2) labeling individual high-concentration dye patches in the binarized images;and 3) pixel-counting to measure the area and perimeter of each dye patch. We examine the variations of fractal dimension of patches, and the fractal dimension is observed to be almost constant irrespective of the distance from the source. The kurtosis of the probability density function curve of the logarithm dimensionless dye patch areas is found to be related with the downstream diffusion distance, based on which an inverse estimation method to locate a passive-scalar point source is proposed and evaluated.

关键词： Graphical Analysis Inverse Problem Passive Scalar Diffusion Source Estimation Turbulent Flow

Analysis of High Concentration Spikes Appearing in Mass Plume in Nearly Homogeneous Turbulent Flow Based on the PDF Transport Equation

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Open Journal of Fluid Dynamics 2016年第4期6卷 472-495页

作者： Masaya Endo Qianqian Shao Takahiro Tsukahara yasuo kawaguchi Department of Mechanical Engineering Tokyo University of Science Chiba Japan

To evaluate the pollutant dispersion in background turbulent flows, most researches focus on statistical variation of concentrations or its fluctuations. However, those time-averaged quantities may be insufficient for risk assessment, because there emerge many high-intensity pollutant areas in the instantaneous concentration field. In this study, we tried to estimate the frequency of appearance of the high concentration areas in a turbulent flow based on the Probability Density Function (PDF) of concentration. The high concentration area was recognized by two conditions based on the concentration and the concentration gradient values. We considered that the estimation equation for the frequency of appearance of the recognized areas consisted of two terms based on each condition. In order to represent the two terms with physical quantities of velocity and concentration fields, simultaneous PIV (Particle Image Velocimetry) and PLIF (Planar Laser-Induced Fluorescence) measurement and PLIF time-serial measurement were performed in a quasi-homogeneous turbulent flow. According to the experimental results, one of the terms, related to the condition of the concentration, was found to be represented by the concentration PDF, while the other term, by the streamwise mean velocity and the integral length scale of the turbulent flow. Based on the results, we developed an estimation equation including the concentration PDF and the flow features of mean velocity and integral scale of turbulence. In the area where the concentration PDF was a Gaussian one, the difference between the frequencies of appearance estimated by the equation and calculated from the experimental data was within 25%, which showed good accuracy of our proposed estimation equation. Therefore, our proposed equation is feasible for estimating the frequency of appearance of high concentration areas in a limited area in turbulent mass diffusion.

关键词： High Concentration Spikes Quasi-Homogeneous Turbulence Turbulent Mass Diffusion Concentration PDF Transport Equation PIV and PLIF Simultaneous Measurement

Diffusion Process of High Concentration Spikes in a Quasi-Homogeneous Turbulent Flow

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Open Journal of Fluid Dynamics 2016年第4期6卷 371-390页

作者： Masaya Endo Qianqian Shao Takahiro Tsukahara yasuo kawaguchi Department of Mechanical Engineering Tokyo University of Science Chiba Japan

When a mass spreads in a turbulent flow, areas with obviously high concentration of the mass compared with surrounding areas are formed by organized structures of turbulence. In this study, we extract the high concentration areas and investigate their diffusion process. For this purpose, a combination of Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV) techniques was employed to obtain simultaneously the two fields of the concentration of injected dye and of the velocity in a water turbulent channel flow. With focusing on a quasi-homogeneous turbulence in the channel central region, a series of PLIF and PIV images were acquired at several different downstream positions. We applied a conditional sampling technique to the PLIF images to extract the high concentration areas, or spikes, and calculated the conditional-averaged statistics of the extracted areas such as length scale, mean concentration, and turbulent diffusion coefficient. We found that the averaged length scale was constant with downstream distance from the diffusion source and was smaller than integral scale of the turbulent eddies. The spanwise distribution of the mean concentration was basically Gaussian, and the spanwise width of the spikes increased linearly with downstream distance from the diffusion source. Moreover, the turbulent diffusion coefficient was found to increase in proportion to the spanwise distance from the source. These results reveal aspects different from those of regular mass diffusion and let us conclude that the diffusion process of the spikes differs from that of regular mass diffusion.

关键词： Turbulent Transport High Concentration Spikes Quasi-Homogeneous Turbulent Flow Conditional Sampling Technique PIV and PLIF Measurements Passive Scalar Diffusion

Abscess in the inguinal hernial sac after peritonitis surgery: A case report

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World Journal of Gastroenterology 2009年第8期15卷 1007-1009页

作者： Satoshi Ikeda Haruka Takeda Masanori Yoshimitsu Takao Hinoi Makoto Yoshida Daisuke Sumitani Yuji Takakura yasuo kawaguchi Manabu Shimomura Masakazu Tokunaga Katsufumi Kawahori Hideki Ohdan Masazumi Okajima Department of Endoscopic Surgery and Surgical Science Graduate School of Biomedical Science Hiroshima University Hiroshima 734-8551 Japan Department of Surgery Division of Frontier Medical Science Programs for Biomedical Research Graduate School of Biomedical Science Hiroshima University Hiroshima 734-8551 Japan

In this paper, we report an extremely rare case of an abscess that developed in the inguinal hernial sac after surgery for peritonitis. A 60-year-old man underwent laparoscopic low anterior resection for rectal cancer. One day after this operation, peritoneal drainage and ileostomy were performed for rectal anastomotic leakage. Five days after the second operation, computed tomography revealed an abscess in the left inguinal hernial sac. Subsequently, hernioplasty and resection of the inflamed sac were performed.

关键词： Inguinal hernia Hernial sac abscess Peritonitis Anastomotic leakage, Rectal cancer

零下温度时二维通道内界面活性剂减阻流动的实验研究

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西安交通大学学报 2006年第1期40卷 79-83页

作者：魏进家川口靖夫西安交通大学动力工程多相流国家重点实验室西安710049 东京理科大学机械工程系日本千叶县2788510

为了进行零下温度时区域供冷系统的界面活性剂减阻设计，测量了-5℃时以质量分数为20％的甘醇不冻液为溶剂的界面活性剂溶液油醇基二羟乙基甲基氯化铵在二维通道内的减阻特性，同时用粒子成像测速仪对减阻流动的湍流特性进行了测量．实... 详细信息

为了进行零下温度时区域供冷系统的界面活性剂减阻设计，测量了-5℃时以质量分数为20％的甘醇不冻液为溶剂的界面活性剂溶液油醇基二羟乙基甲基氯化铵在二维通道内的减阻特性，同时用粒子成像测速仪对减阻流动的湍流特性进行了测量．实验发现：质量分数为5×10^-5～5×10^-4的低浓度油醇基二羟乙基甲基氯化铵界面活性剂溶液在一定的雷诺数范围内均呈现减阻特性，且其减阻特性与质量分数和温度呈复杂关系，最大减阻值可高达70％以上；在湍流液体中只需加入少量该界面活性剂即可大幅度减少液体输送的动力消耗．与单独的质量分数为20％的甘醇不冻液湍流流动相比，添加界面活性剂抑制了湍流速度脉动，使雷诺应力完全消失．

关键词：区域供冷界面活性剂减阻湍流特性

界面活性剂减阻溶液在自由面旋转流中的流动特性研究

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西安交通大学学报 2006年第3期40卷 315-318,352页

作者：魏进家川口靖夫西安交通大学动力工程多相流国家重点实验室西安710049 东京理科大学机械工程系日本千叶县2788510

利用粒子成像测速仪系统对开口圆柱容器内由旋转底盘带动的低浓度十六烷基三甲基氯化铵界面活性剂溶液的旋转流动进行了实验研究．界面活性剂溶液的质量分数范围为5×10^-5～1×10^-3，雷诺数为4．3×10^4．实验得到了旋转流体自由面中... 详细信息

利用粒子成像测速仪系统对开口圆柱容器内由旋转底盘带动的低浓度十六烷基三甲基氯化铵界面活性剂溶液的旋转流动进行了实验研究．界面活性剂溶液的质量分数范围为5×10^-5～1×10^-3，雷诺数为4．3×10^4．实验得到了旋转流体自由面中心下陷深度与界面活性剂溶液质量分数和减阻之间的对应关系，为小黏弹性低浓度界面活性剂溶液的减阻特性判别提供了一种方法，同时也得到了界面活性剂溶液小黏弹性对自由面旋转流动涡结构的影响规律．实验发现对于水的自由面旋转流而言，其中央轴对称平面内的流动形态与低雷诺数情况有很大的不同，由离心力引起的惯性驱动涡被由涡分裂引起的反方向旋转涡推挤到自由面与容器壁面之间的角落内；对于质量分数为1×10^-3的界面活性剂溶液而言，其中央轴对称平面内弹性驱动涡占主导地位，惯性驱动涡被挤压在容器底部与容器壁面之间的角落内。

关键词：自由面旋转流界面活性剂减阻粒子成像测速仪