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Side Wall Effects on the Hydrodynamics of a Floating Body by ImageGreen Function Based on TEBEM 被引量:3
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作者 Jikang Chen Lijia Wang Wenyang Duan 《Journal of Marine Science and Application》 CSCD 2018年第3期353-361,共9页
A novel numerical model based on the image Green function and first-order Taylor expansion boundary element method(TEBEM), which can improve the accuracy of the hydrodynamic simulation for the non-smooth body, was dev... A novel numerical model based on the image Green function and first-order Taylor expansion boundary element method(TEBEM), which can improve the accuracy of the hydrodynamic simulation for the non-smooth body, was developed to calculate the side wall effects on first-order motion responses and second-order drift loads upon offshore structures in the wave tank. This model was confirmed by comparing it to the results from experiments on hydrodynamic coefficients, namely the first-order motion response and second-order drift load upon a hemisphere, prolate spheroid, and box-shaped barge in the wave tank. Then,the hydrodynamics of the KVLCC2 model were also calculated in two wave tanks with different widths. It was concluded that this model can predict the hydrodynamics for offshore structures effectively, and the side wall has a significant impact on the firstorder quantities and second-order drift loads, which satisfied the resonant rule. 展开更多
关键词 Taylor expansion boundary element method Side wall effects Image Green function HYDRODYNAMICS Sharp corner floating body
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Geometric effects resulting from the asymmetry of dipping fault:Hanging wall/ footwall effects
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作者 王栋 谢礼立 胡进军 《Acta Seismologica Sinica(English Edition)》 CSCD 2008年第3期275-282,332,共9页
Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rup... Root-mean-square distance Drms with characteristic of weighted-average is introduced in this article firstly. Drms can be used to capture the general proximity of a site to a dipping fault plane comparing with the rupture distance Drup and the seismogenic distance Dseis. Then, using Drup, Dseis and Drms, the hanging wall/footwall effects on the peak ground acceleration (PGA) during the 1999 Chi-Chi earthquake are evaluated by regression analysis. The logarithm residual shows that the PGA on hanging wall is much greater than that on footwall at the same Drup or Dseis when the Drup or Dseis is used as site-to-source distance measure. In contrast, there is no significant difference between the PGA on hanging wall and that on footwall at the same Drms when Drms is used. This result confirms that the hanging wall/footwall effect is mainly a geometric effect caused by the asymmetry of dipping fault. Therefore, the hanging wall/footwall effect on the near-fault ground motions can be ignored in the future attenuation analysis if the root-mean-square distance Drms is used as the site-to-source distance measure. 展开更多
关键词 root-mean-square distance rupture distance hanging wall/footwall effects peak acceleration attenuation relationship near-fault ground motion
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CFD modeling of pressure drop and drag coefficient in fixed beds:Wall effects 被引量:6
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作者 Rupesh K.Reddy Jyeshtharaj B.Joshi 《Particuology》 SCIE EI CAS CSCD 2010年第1期37-43,共7页
Simulations of fixed beds having column to particle diameter ratio (D/dp) of 3, 5 and 10 were performed in the creeping, transition and turbulent flow regimes, where Reynolds number (dpVLρL/μL) was varied from 0... Simulations of fixed beds having column to particle diameter ratio (D/dp) of 3, 5 and 10 were performed in the creeping, transition and turbulent flow regimes, where Reynolds number (dpVLρL/μL) was varied from 0.1 to 10,000. The deviations from Ergun's equation due to the wall effects, which are important in D/dp 〈 15 beds were well explained by the CFD simulations. Thus, an increase in the pressure drop was observed due to the wall friction in the creeping flow, whereas, in turbulent regime a decrease in the pressure drop was observed due to the channeling near the wall. It was observed that, with an increase in the D/dp ratio, the effect of wall on drag coefficient decreases and drag coefficient nearly approaches to Ergun's equation. The predicted drag coefficient values were in agreement with the experimental results reported in the literature, in creeping flow regime, whereas in turbulent flow the difference was within 10-15%. 展开更多
关键词 Computational fluid dynamics Fixed bed wall effects Pressure drop Drag coefficient
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EFFECT OF SLIP AND MAGNETIC FIELD ON PERISTALTIC FLOW IN AN INCLINED CHANNEL WITH WALL EFFECTS 被引量:1
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作者 A. V. RAMANA KUMARI G. RADHAKRISHNAMACHARYA 《International Journal of Biomathematics》 2012年第6期1-17,共17页
Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall sl... Peristaltic transport of a Newtonian incompressible fluid in the presence of applied mag netic field in an inclined channel with slip is investigated. A perturbation method of solu tion is obtained in terms of wall slope parameter and analytical expressions are derived for average velocity and stream function using Saffman slip condition. The effects of var ious relevant parameters on average velocity and stream line pattern have been studied. It is found that average velocity increases with slip and decreases with permeability and magnetic parameter. 展开更多
关键词 PERISTALSIS magnetic field SLIP inclined channel and wall effects.
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Effects of hanging wall and footwall on demand of structural input energy during the 2008 Wenchuan earthquake 被引量:2
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作者 Lu Shunan Li Shuang +1 位作者 Zhai Changhai Xie Lili 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2013年第1期1-12,共12页
Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated,focusing on the influence of these differences on ... Systematic differences in the duration and frequency content of ground motions from the hanging wall and footwall during the 2008 Wenchuan earthquake are investigated,focusing on the influence of these differences on structural input energy based on the elastic and inelastic energy responses of structures.A comparison of the input energy spectra between the hanging wall and the footwall reveal that the structural input energy on the hanging wall is not amplified due to the short duration and low peak ground velocity to acceleration ratio(V/A).However,the larger demand of structural input energy on the footwall in the range of medium and long periods is observed and the demand increases up to 50% relative to the average level of structural input energy for rupture distances larger than 30 km.The importance of considering the footwall effect on structural input energy when comparing ground motions in the range of medium and long periods is recognized. 展开更多
关键词 Wenchuan earthquake DURATION frequency content hanging wall effect footwall effect input energy
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Flow behavior in microchannel made of different materials with wall slip velocity and electro-viscous effects 被引量:5
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作者 Lei Wang Jiankang Wu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第1期73-80,共8页
In a microfluidic system, flow slip velocity on a solid wall can be the same order of magnitude as the average velocity in a microchannel. The flow-electricity interaction in a complex microfluidic system subjected to... In a microfluidic system, flow slip velocity on a solid wall can be the same order of magnitude as the average velocity in a microchannel. The flow-electricity interaction in a complex microfluidic system subjected to joint action of wall slip and electro-viscous effect is an important topic. This paper presents an analytic solution of pressuredriven liquid flow velocity and flow-induced electric field in a two-dimensional microchannel made of different materials with wall slip and electro-viscous effects. The Poisson- Boltzmann equation and the Navier-Stokes equation are solved for the analytic solutions. The analytic solutions agree well with the numerical solutions. It was found that the wall slip amplifies the fow-induced electric field and enhances the electro-viscous effect on flow. Thus the electro-viscous effect can be significant in a relatively wide microchannel with relatively large kh, the ratio of channel width to thickness of electric double layer, in comparison with the channel without wall slip. 展开更多
关键词 MICROCHANNEL wall slip - Electro-viscous effects
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Three-dimensional dynamics of a single bubble rising near a vertical wall:Paths and wakes
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作者 Hong-jie Yan He-Yang Zhang +2 位作者 Hui-Min Zhang Yi-Xiang Liao Liu Liu 《Petroleum Science》 SCIE EI CAS CSCD 2023年第3期1874-1884,共11页
In order to clarify the migration mechanism and wake behavior of a single bubble rising near a vertical wall,three-dimensional direct numerical simulations are implemented based on the open-source soft-ware Basilisk a... In order to clarify the migration mechanism and wake behavior of a single bubble rising near a vertical wall,three-dimensional direct numerical simulations are implemented based on the open-source soft-ware Basilisk and various types of migration paths like linear,zigzag and spiral are investigated.The volume of fluid(VOF)method is used to capture the bubble interface at a small scale,while the gas-liquid interface and high-velocity-gradient regions in the flow field are encrypted with the adaptive mesh refinement technology.The results show that the vertical wall has an obstructive effect on the diffusion of the vortex boundary layer on the surface of the bubble migrating in a straight line,and the resulting reaction force tends to push the bubbles away from the wall surface.For the zigzag or spiral movement of a bubble in the x-y plane,the perpendicular wall is an unstable factor,but on the contrary,the motion in the z-y plane is stabilized. 展开更多
关键词 BUBBLE wall effect TRAJECTORY Wake structure VOF Basilisk
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Preliminary analysis of the hanging wall effect and velocity pulse of the 5.12 Wenchuan earthquake 被引量:11
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作者 Liu Qifang and Li Xiaojun Institute of Engineering Mechanics, China Earthquake Administration, Harbin 150080, China Associate Professor Professor 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第2期165-177,共13页
A preliminary study of the PGA attenuation, hanging wall effect and velocity pulse characteristics from the 2008 Wenchuan earthquake ofMS -8.0 is described in this paper. The study was carried out through analyses in ... A preliminary study of the PGA attenuation, hanging wall effect and velocity pulse characteristics from the 2008 Wenchuan earthquake ofMS -8.0 is described in this paper. The study was carried out through analyses in the time and frequency domains of main earthquake records. In the PGA attenuation study, records from 316 stations less than 1000 km from the surface rupture of the fault were used as a database and attenuation relationships were developed and compared with some existing relationships that are widely used in China's Mainland, Chinese Taiwan and the US. At the same time, records from 28 stations less than 100 km from the fault were used to study the hanging wall effect and velocity pulse characteristics of this earthquake based on the distribution of PGA, PGV, spectral acceleration, and the velocity pulse peak, and the results are compared with the 1999 Chi-Chi earthquake. In addition, the large PGAs of the UD components observed in this event are also discussed in this paper. From the results of the preliminary study, some conclusions are developed and suggestions for further research are proposed. 展开更多
关键词 Wenchuan earthquake hanging wall effect velocity pulse ATTENUATION
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Wall Effect of Underwater Explosion Load Based on Wave Motion Theories 被引量:2
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作者 肖巍 姚熊亮 郭君 《China Ocean Engineering》 SCIE EI CSCD 2014年第5期587-598,共12页
Owing to the existence of the flow field boundary, the shock wave load near the boundary is different from the freefield shock wave load. In the present paper, the hull plate load subjected to underwater shock wave is... Owing to the existence of the flow field boundary, the shock wave load near the boundary is different from the freefield shock wave load. In the present paper, the hull plate load subjected to underwater shock wave is investigated based onwave motion theories; in addition, the experimental study of the hull plate load is carried out. According to the theoreticalanalysis of the hull plate pressure, we find that the hull plate pressure oscillates repeatedly and decays rapidly with timepassing, the maximum hull plate pressure is 2/(1+n) times the maximum free field pressure, where n is the ratio ofimpedance, and the impulse is much smaller than the free field impulse. Compared with the experimental study, thetheoretical results agree well with the experimental data. 展开更多
关键词 underwater explosion wave motion theories wall effect IMPEDANCE EXPERIMENT
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A Free Surface Frequency Domain Green Function with Viscous Dissipation and Partial Reflections from Side Walls 被引量:2
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作者 Hongde Qin Jing Shen Xiaobo Chen 《Journal of Marine Science and Application》 2011年第3期259-264,共6页
The free-surface Green function method is widely used in solving the radiation or diffraction problems caused by a ship or ocean structure oscillating on the waves. In the context of inviscid potential flow, hydrodyna... The free-surface Green function method is widely used in solving the radiation or diffraction problems caused by a ship or ocean structure oscillating on the waves. In the context of inviscid potential flow, hydrodynamic problems such as multi-body interaction and tank side wall effect cannot be properly dealt with based on the traditional free-surface frequency domain Green function method, in which the water viscosity is omitted and the energy dissipation effect is absent. In this paper, an open-sea Green function with viscous dissipation was presented within the theory ofvisco-potential flow. Then the tank Green function with a partial reflection from the side walls in wave tanks was formulated as a formal sum of open-sea Green functions representing the infinite images between two parallel side walls of the source in the tank. The new far-field characteristics of the tank Green function is vitally important fur improving the validity of side-wall effects evaluation, which can be used in supervising the tank model tests. 展开更多
关键词 Green function viscous dissipation side wall effect partial reflection
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A new attenuation model of near-fault ground motions with consideration of the hanging wall effect in the Wenchuan earthquake 被引量:1
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作者 Peng Lei Xie Lili +1 位作者 Hu Jinjun Wang Dong 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2011年第3期313-323,共11页
The hanging wall effect is an important factor that impacts the characteristics of strong ground motions in near-fault areas. Based on a residual analysis of ground motion parameters characterizing the hanging wall ef... The hanging wall effect is an important factor that impacts the characteristics of strong ground motions in near-fault areas. Based on a residual analysis of ground motion parameters characterizing the hanging wall effect and in recognition of the nature of the effect, many models have been developed. In this study, after a comprehensive analysis of two existing models, a new model is proposed and used to model the hanging wall effect in horizontal peak ground acceleration (PGAH) and spectral acceleration (SAH) at a period of 0.1s in the Wenchuan earthquake. Finally, comparisons between the modeling results of the hanging wall effect in the Wenchuan earthquake and the results predicted by using Abrahamson and Silva's NGA model (AS NGA) indicate that the AS NGA model predicts a much higher hanging wall effect than the model developed in this paper. Furthermore, the AS NGA model predicts a large hanging wall effect even at great distances, while the proposed model more accurately captures the trend of the effect. 展开更多
关键词 hanging wall effect Wenchuan earthquake attenuation relationship NGA model
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Structural effect of a soft-hard backfill wall in a gob-side roadway 被引量:1
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作者 Wang Hongsheng Zhang Dongsheng Fan Gangwei 《Mining Science and Technology》 EI CAS 2011年第3期313-318,共6页
The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the... The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall. 展开更多
关键词 Gob-side roadway Backfill wall Structural effect Dynamic effectMain roof
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COALESCENCE INDUCED GRADIENT MORPHOLOGY NEAR A WALL IN PHASE SEPARATED POLYMER BLENDS DURING QUIESCENT ANNEALING
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作者 Wei Yu Chi-xing Zhou De-lu Zhao Department of Polymer Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 China State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences Beijing 100080, China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2002年第6期543-550,共8页
A fast coalescence mechanism is proposed to account for the wall effect on the formation of gradient morphology in phase separated polymer blends during quiescent annealing. The existence of solid wall with high polar... A fast coalescence mechanism is proposed to account for the wall effect on the formation of gradient morphology in phase separated polymer blends during quiescent annealing. The existence of solid wall with high polarity is believed to change the potential field around the dispersed particles near the wall. This additional potential interaction between the solid wall and the dispersed particles causes faster coalescence of the dispersed particles near the wall than in the bulk. The gradient phase morphology thus formed can be predicted by combining the wall-particle interaction and the touch-coalescence mechanism. The effect of interfacial tension on the gradient morphology is also discussed. 展开更多
关键词 gradient morphology wall effect COALESCENCE polymer blends interfacial tension
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Influence of Wall Effect on Comprehensive Controllability for Ducted Fan Aircraft
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作者 Tianfu Ai Changle Xiang +2 位作者 Bin Xu Wei Fan Yibo Zhang 《Journal of Beijing Institute of Technology》 EI CAS 2020年第4期581-591,共11页
A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification... A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model.Based on the duct test bench experiment and computational fluid dynamics(CFD)simulation analysis,the expressions between the different distances dWE from the rotor center of the prototype to the wall and the thrust,reaction torque,and tilting moment of the system under hovering conditions are obtained.The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance dWE and the comprehensive controllability of the system.The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance dWE,and only the controllability vector of the rolling channel increases significantly.At the same time,the tilting moment also increases significantly,which strengthens the tendency of the prototype to tilt towards the wall. 展开更多
关键词 coaxial ducted fan aircraft hovering condition wall effect tilting moment comprehensive controllability analysis
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Investigation into the hydrodynamics of liquid-solid inclined micro-fluidized beds
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作者 Yi Zhang Nina Ullah +2 位作者 Richard Law David Reay Vladimir Zivkovic 《Resources Chemicals and Materials》 2022年第1期8-15,共8页
The inclined micro-fluidized bed(MFB)can enhance heat and mass transfer rates compared to the vertically aligned counterparts,but the increased significance of surface forces and wall effects may cause poor fluidizati... The inclined micro-fluidized bed(MFB)can enhance heat and mass transfer rates compared to the vertically aligned counterparts,but the increased significance of surface forces and wall effects may cause poor fluidization performance.In this paper,the effects of column inclination and different particle-to-bed ratios(d_(P)/d_(B))on the solid hydrodynamics are investigated in an inclined micro-fluidized bed.The results validated the suitability of using the Ergun equation to predict minimum fluidization velocities due to small deviations between 1.01 and 1.81 times the theoretical values,for a particle-to-bed ratio ranging from 0.025 to 0.165 at inclinations between 0°and 10°.Investigation into the effects on bed expansion behavior showed that the bed contracted with an increase in bed inclination.An unexpected observation during the bed expansion was the appearance of a secondary high voidage region and the appearance of strong circulation patterns with an increase in bed inclination.A detailed analysis of this phenomenon suggested the presence of a critical angle at 6°and 10°for the 85μm particles,4×4 mm bed cross-section and 165μm particles,1×1 mm bed cross-section,respectively.However,the liquid-solid back-mixing was observed due to the modified particle trajectories resulted in the disappearance of the high voidage region.This paper gives new insights into the micro-fluidization behavior in inclined beds thus contributing to the development of micro-fluidized beds and their future applications. 展开更多
关键词 Micro-fluidized bed INCLINATION Minimum fluidization velocity wall effects
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Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs 被引量:2
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作者 Asheesh Nautiyal Chien-Song Chyang +1 位作者 Pin-Wei Li Hsin-Yung Hou 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第7期848-861,共14页
In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for ... In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, Dxand Dy, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted.Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that Dxand Dyare nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on Dxis minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor. 展开更多
关键词 Gas dispersion coefficient Horizontal mixing wall effect Surface modeling
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Settling velocity of equiaxed dendrites in a tube 被引量:1
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作者 周鹏 王猛 +1 位作者 林鑫 黄卫东 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第1期518-523,共6页
The settling velocity of equiaxed dendrites can cause macrosegregation and influence the structure of the equiaxed zone during the casting solidification process. So an understanding of the settling characteristics is... The settling velocity of equiaxed dendrites can cause macrosegregation and influence the structure of the equiaxed zone during the casting solidification process. So an understanding of the settling characteristics is needed to predict the structure and segregation in castings. The settling velocity of NH4Cl equiaxed dendrites of non-spherical geometry was studied experimentally in an NH4Cl-70wt.%H2O solution. A calculation formula was proposed to calculate the settling velocity of sediment equiaxed dendrites in a tube filled with saturated solution at a moderate Reynolds number region. The retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity were taken into account in the development of the calculation formula, and the correction function B of the drag coefficient with consideration of the retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity of the equiaxed dendrite was calibrated according to the experimental results. A comparison showed that the formula has a good accordance with the experimental results. 展开更多
关键词 equiaxed dendrite settling velocity morphology effect wall effect
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Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber 被引量:4
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作者 Xu-Dong Zhang Bao-Chun Fan +2 位作者 Ming-Yue Gui Zhen-Hua Pan Gang Dong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第1期66-72,共7页
Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate ... Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems. 展开更多
关键词 Continuously rotating detonation - Three- dimensional flow field structure - Numerical study Detonation parameters deficit ~ effects of wall geometries
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EFFECTS OF WALL ROUGHNESS ON COHERENT STRUCTURE IN TURBULENT SHEAR FLOWS 被引量:1
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作者 LIANG ZAICHAO LIU SHIHE, Research Institute of Water Conservancy and Hydraulic Power, Wuhan University of Hydraulic and Electric Engineering, Wuhan, Hubei, P.R. China 《Journal of Hydrodynamics》 SCIE EI CSCD 1989年第1期15-21,共7页
There are many examples that fluid flows on rough wall, such as channel flow in nature, pipe flow, etc. In order to know the flow structure of real fluids, it is important to study the effects of wall roughness on coh... There are many examples that fluid flows on rough wall, such as channel flow in nature, pipe flow, etc. In order to know the flow structure of real fluids, it is important to study the effects of wall roughness on coherent structure in turbulent shear flows. The experiments were carried out in a square glass channel, which is 600cm long, with the cross section of 30×25cm^2. The flow velocity was varied from 2 to 40 cm/s. Uniform sands whose diameters were 0.0012cm, 0.2gcm, 0.385cm, 0.594cm and 0.896cm respectively were glued to the floor of the channel. The rough Reynolds number Re_Δ= U_*Δ/ν=0.04~73, where U_*is the shear velocity, Δ is the diame- ter of uniform sand, v is the kinematic viscosity coefficient. Hydrogen bubble technique for flow visualization and HWL-II hot-film anemometer for velocity mea- surement were used in the experiments. 展开更多
关键词 effects OF wall ROUGHNESS ON COHERENT STRUCTURE IN TURBULENT SHEAR FLOWS FLOW
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Settling behavior of spherical particles in eccentric annulus filled with viscous inelastic fluid
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作者 Zhao-Peng Zhu Xian-Zhi Song +4 位作者 Ergun Kuru Hong-Bo Chen Bu-Wen Yu Zi-Chao Lin Yan-Xin Sun 《Petroleum Science》 SCIE CAS CSCD 2022年第4期1653-1663,共11页
Hole cleaning is a complex process as there are many variables affecting cuttings removal(e.g.drilling fluid type,density,flow rate and rheological properties,cuttings size,drill pipe rotation speed).With the increasi... Hole cleaning is a complex process as there are many variables affecting cuttings removal(e.g.drilling fluid type,density,flow rate and rheological properties,cuttings size,drill pipe rotation speed).With the increasing number of drilling small diameter wells(e.g.coiled tubing drilling applications,ultra-deep wells drilled for exploitations of unconventional oil and gas resources),the wall resistance of the micro annulus also emerges as one of the most critical factors affecting the cuttings accumulation in wellbore.The eccentricity of drill pipes commonly observed during the drilling process of ultra-deep well and coiled tubing well makes the wall resistance effect on the cuttings transport even more prominent.Understanding the wall resistance effect on the particle settling behavior in eccentric annuli is,therefore,crucial for hydraulic design of efficient cuttings transport operations in these wells.In this study,a total of 196 sets of particle settling experiments were carried out to investigate the particle settling behavior in eccentric annuli filled with power-law fluids.The test matrix included the eccentricity ranges of 0-0.80,the dimensionless diameter ranges of 0.13-0.75 and the particle Reynolds number ranges of 0.09-32.34.A high-speed camera was used to record the particle settling process and determine the influences of the eccentricity,the dimensionless diameter,the fluid rheological properties,and the solid particle characteristics on the wall factor and the particle settling velocity.The functional relationship among the dimensionless diameter,the particle Reynolds number,and the wall factor was determined by using the method of controlling variables.An eccentric annulus wall factor model with average relative error of 5.16%was established.Moreover,by introducing Archimedes number,an explicit model of particle settling velocity in the eccentric annulus with average relative error of 10.17%was established.A sample calculation of particle settling velocity was provided to show the application of the explicit model.Results of this study can be used as a guideline by field engineers to improve hydraulic design of cuttings transport operations in concentric and eccentric annuli. 展开更多
关键词 Cuttings transport Particle settling velocity Eccentric annulus wall effect
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