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Saffman–Taylor instability in eccentric cylinders at gaseous cavitation

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Friction 2024年第2期12卷 356-362页

作者： Anatoliy A.MONAKHOV Nikolay BUKHARIN institute of mechanics Moscow State UniversityMoscow 119899Russia Thermofluid Solutions Ltd. CalgaryAlberta T3G4E8Canada

A flow of silicon fluid in the gap between eccentric cylinders was studied *** condition of gaseous cavitation inception during the rotation of internal cylinder was *** was shown that at reduction of the gap between cylinders Saffman–Taylor instability appeared on surface of the internal cylinder and then gaseous cavitation was *** of one uniform gas formation appearance under this type of instability was demonstrated.

关键词： gaseous cavitation Saffman-Taylor instability eccentric cylinders friction lubrication theory

Numerical Simulation of Thermocapillary Convection with Evaporation Induced by Boundary Heating

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fluid Dynamics & Materials Processing 2024年第7期20卷 1667-1686页

作者： O.N.Goncharova V.B.Bekezhanova Altai State University Institute of Mathematics and Information TechnologiesBarnaul656049Russia institute of Computational Modelling SB RAS Department of Differential Equations of MechanicsKrasnoyarsk660036Russia

The dynamics of a bilayer system filling a rectangular cuvette subjected to external heating is *** influence of two types of thermal exposure on the flow pattern and on the dynamic contact angle is *** particular,the cases of local heating from below and distributed thermal load from the lateral walls are *** simulation is carried out within the frame of a two-sided evaporative convection model based on the Boussinesq approximation.A benzine–air system is considered as reference *** variation in time of the contact angle is described for both heating *** lateral heating,near-wall boundary layers emerge together with strong convection,whereas the local thermal load from the lower wall results in the formation of multicellular motion in the entire volume of the fluids and the appearance of transition regimes followed by a steady-state *** results of the present study can aid the design of equipment for thermal coating or drying and the development of methods for the formation of patterns with required structure and morphology.

关键词： Thermocapillary convection two-phase system numerical modeling contact angle

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频带禁区:远离共振的管道设计策略

Acta Mechanica Sinica 2024年第3期40卷 191-201页

作者：邓天昌丁虎 Shanghai Key Laboratory of mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China Shanghai institute of Aircraft mechanics and Control Shanghai200092China

本文介绍了一种通过调整卡箍使得管道避免发生共振的设计策略.当管道的固有频率在机械设备运作时产生的振动频率范围内,会引发共振现象,给机械设备的正常操作带来严重的灾难.因此,把机械设备操作产生的振动频率范围定义为频带禁区.通常... 详细信息

本文介绍了一种通过调整卡箍使得管道避免发生共振的设计策略.当管道的固有频率在机械设备运作时产生的振动频率范围内,会引发共振现象,给机械设备的正常操作带来严重的灾难.因此,把机械设备操作产生的振动频率范围定义为频带禁区.通常,工程中的管道被简化为多跨输流管道:通过将卡箍简化为线性和扭转刚度,建立了多跨输流管道的整体管道模型.通过采用Galerkin截断方法并应用广义特征值方法,获得了多跨输流管道的固有频率.通过对比不同长度的管道固有频率和频带禁区,定义了管长的安全范围和共振范围分别为频带禁区的外和内,并且通过分析卡箍的影响推导得出了绝对安全长度和绝对共振长度.此外,还确定了卡箍刚度和位置对安全范围的影响.结果表明,通过调整卡箍的线性刚度、扭转刚度和位置,管道的安全范围会发生显著地变化.根据这些结果,提出了一种管道设计策略,从而避免了管道的共振发生,并减少了使用卡箍的数量.最后,以飞机上的一段管道为例进行了设计,结果表明:通过调整卡箍,管道的固有频率成功地远离了频带禁区,因而在飞机的运行过程中不会发生共振.总而言之,通过调整卡箍的刚度或位置,可以获得避免多跨输流管道发生共振的设计策略.

关键词： Pipe conveying fluid Frequency preserve Natural frequency Resonance Multispan Retaining clip

Investigation of Cavitation in NaCl Solutions in a Sonochemical Reactor Using the Foil Test Method

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fluid Dynamics & Materials Processing 2024年第5期20卷 1093-1102页

作者： Michael Kuchinskiy Tatyana Lyubimova Konstantin Rybkin Anastasiia Sadovnikova Vasiliy Galishevskiy institute of Continuous Media mechanics UB RAS Perm614013Russia Faculty of Physics Perm State UniversityPerm614068Russia

Ultrasonic baths and sonochemical reactors are widely used in industrial applications dealing with surface cleaningand chemical synthesis. The processes of erosion, cleaning and structuring of the surface can be typically controlledby changing relevant influential parameters. In particular, in this work, we experimentally investigate theeffect of NaCl concentration (0–5.5 mol/L) on the erosion of an aluminum foil under ultrasonic exposure at afrequency of 28 kHz. Special attention is paid to the determination of cavitation zones and their visualizationusing heat maps. It is found that at low NaCl concentration (0.3 mol/L), the foil destruction rate is higher thanin distilled water. At higher concentrations of salt, cavitation takes place mainly in the upper part of the container.

关键词： Ultrasound NaCl solution foil test cavitation activity

Effect of absorption boundary layer on nonlinear flow in low permeability porous media

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Journal of Central South University 2011年第4期18卷 1299-1303页

作者：王学武杨正明齐亚东黄延章 institute of porous flow and fluid mechanics Chinese Academy of Sciences Langfang Branch Petro China Exploration and Development Research Institute

Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring *** the throat distribution and capillary model,the thickness of fluid boundary layer under different pressure gradients was calculated,and the mechanism and influencing factors of nonlinear percolation were *** results show that the percolation curve of ultra-low rocks is nonlinear,and apparent permeability is not a constant which increases with pressure *** absorption boundary layer decreases with the increase of pressure gradient,and changes significantly especially in low pressure gradient,which is the essence of nonlinear *** absorption boundary layer is also found to be impacted by the surface property of rocks.

关键词： low permeability reservoirs percolation absorption boundary layer capillary model

Water coning mechanism in Tarim fractured sandstone gas reservoirs

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Journal of Central South University 2015年第1期22卷 344-349页

作者：沈伟军刘晓华李熙喆陆家亮 institute of porous flow and fluid mechanics Chinese Academy of Sciences University of Chinese Academy of Sciences Petro China Research institute of Petroleum Exploration and Development-Langfang

The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomenon caused by the imbalance between gravity and viscous forces around the completion interval. There are several controllable and uncontrollable parameters influencing this problem. In order to simulate the key parameters affecting the water coning phenomenon, a model was developed to represent a single well with an underlying aquifer using the fractured sandstone gas reservoir data of the A-Well in Dina gas *** parametric study was performed by varying six properties individually over a representative range. The results show that matrix permeability, well penetration(especially fracture permeability), vertical-to-horizontal permeability ratio, aquifer size and gas production rate have considerable effect on water coning in the fractured gas reservoirs. Thus, investigation of the effective parameters is necessary to understand the mechanism of water coning phenomenon. Simulation of the problem helps to optimize the conditions in which the breakthrough of water coning is delayed.

关键词： water coning fractured gas reservoir water cut recovery factor

Analysis of natural vibration of truncated conical shells partially filled with fluid

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International Journal of Mechanical System Dynamics 2024年第2期4卷 142-152页

作者： Sergey A.Bochkarev Sergey V.Lekomtsev Laboratory of Functional Materials Institute of Continuous Media MechanicsUral Branch of Russian Academy of SciencesPermRussian Federation

In this paper,we study the vibrational behavior of shells in the form of truncated cones containing an ideal compressible *** sloshing effect on the free surface of the fluid is *** dynamic behavior of the elastic structure is investigated based on the classical shell theory,the constitutive relations of which represent a system of ordinary differential equations written for new *** fluid vibrations are described in terms of acoustic approximation using the wave equation for hydrodynamic pressure written in spherical *** transformation into the system of ordinary differential equations is carried out by applying the generalized differential quadrature *** formulated boundary value problem is solved by Godunov's orthogonal sweep *** frequencies of shell vibrations are calculated using the stepwise procedure and the Muller *** accuracy and reliability of the obtained results are estimated by making a comparison with the known numerical and analytical *** dependencies of the lowest frequency on the fluid level and cone angle of shells under different combinations of boundary conditions(simply supported,rigidly clamped,and cantilevered shells)have been studied *** conical straight and inverted shells,a numerical analysis has been performed to estimate the possibility of finding configurations at which the lowest natural frequencies exceed the corresponding values of the equivalent cylindrical shell.

关键词： classical shell theory conical shell Godunov's orthogonal sweep method ideal compressible fluid generalized differential quadrature method natural vibrations

Physical simulation experiment and numerical inversion of the full life cycle of shale gas well

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Petroleum Research 2019年第2期4卷 181-190页

作者： Shusheng Gao Huaxun Liu Liyou Ye Zhiming Hu Weiguo An Research institute of Petroleum Exploration&Development CNPCBeijing100083China Department of porous flow&fluid mechanics Research Institute of Petroleum Exploration&DevelopmentPetroChinaHebeiLangfang065007China

The ultra-low porosity and permeability,as well as complex occurrence and transport state of shale reservoir make it possess special L-type production characteristic curve and complicated shale gas flow *** solve the difficulty of collecting complete production data due to short production time and operation discontinuity,a full-diameter core physical simulation experiment on the full lifecycle production process of shale gas well depletion is conducted with the purpose of obtaining many important production data including complete pressure and daily gas output in the simulated production process of shale gas *** experimental results show the production characteristic from simulation is consistent with those from gas *** on the simulation data,the critical desorption pressure(12 MPa)of core,free gas production(3820.8 mL),adsorbed gas production(2151.2 mL),the proportion of the daily gas production between free and absorbed gas under different time and formation pressure,as well as the production time and final recovery rate corresponding to abandoned pressure,can be determined *** inversion is carried out to calculate the production performance curve of shale gas well and predict the development effect of gas well based on well testing and similarity analysis of the dimensionless time between core experiment and gas well ***,the permeability and the fracturing effect(fracture network density)as the keys to the effective development of shale gas reservoirs are *** permeability is the fundamental factor and the fracturing technology is the major means.

关键词： Shale gas well Full lifecycle Physical simulation experiment Numerical inversion Similarity theory Permeability Fracturing effect

LOCAL DISCONTINUOUS GALERKIN METHOD FOR RADIAL porous flow WITH DISPERSION AND ADSORPTION

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Applied Mathematics and mechanics(English Edition) 2004年第9期25卷 977-982页

作者：汪继文刘慈群 State Key Loboratory of Fire Science University of Science and Technolog of China institute of porous flow and fluid mechanics Chinese Academy of Science

Based on the local discontinuous Galerkin methods for time-dependent convection-diffusion systems newly developed by Corkburn and Shu,according to the form of the generalized convection-diffusion equations which model the radial porous flow with dispersion and adsorption,a local discontinuous Galerkin method for radial porous flow with dispersion and adsorption was developed,a high order accurary new scheme for radial porous flow is *** presented method was applied to the numerical tests of two cases of radial porous,i.e., the convection-dispersion flow and the convection-dispersion-adsorption flow,the corresponding parts of the numerical results are in good agreement with the published solutions,so the presented method is *** of the computational cost also shows that the method is practicable.

关键词： dispersion adsorption radial porous flow local discontinuous Galerkin method