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Journal of Applied Mechanics and Technical Physics

2018 year, number 6

On the Impact of Flow-Diverters on the Hemodynamics of Human Cerebral Aneurysms

D. V. Parshin1,2, Yu. O. Kuyanova1,2, D. C. Kislitsin3, U. Windberger4, A. P. Chupakhin1,2
1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Novosibirsk National Research State University, Novosibirsk, 630090, Russia
3Meshalkin National Medical Research Center, Novosibirsk, 630055, Russia
4Center for Biomedical Research, Vienna, 1090, Austria
Keywords: церебральная аневризма, потокперенаправляющий стент, гемодинамика мозга, реконструкция DICOM-изображений, неньютоновская реология крови, cerebral aneurysm, flow-diverter, brain hemodynamics, reconstruction of DICOM images, non-Newtonian blood rheology

Abstract >>
The impact of flow-diverters used in the treatment of cerebral aneurysm on human brain hemodynamics was evaluated qualitatively and quantitatively. Numerical simulation of flow-diverter placement in cerebral vessels with aneurysms for the case history of a real patient was carried out with the commercial ANSYS 17.2 package, using different (Newtonian and non-Newtonian) hydrodynamic models of blood rheology in different parts of the vessel and aneurysm, according to experimental data. It is shown that after flow-diverter placement, the blood flow through the artery segment containing the aneurysm neck decreases, resulting in a redistribution of the cerebral blood flow, which becomes close to a healthy bloodstream. Changes in wall tangential stresses in the flow-diverter region are indicative of possible aneurysm recanalization.

Experimental Investigation of the Flow Over Single and Successive Hills on Smooth and Rough Walls

M. Belmahdi1, R. Zegadi1, S. SimoГ«ns2, S. Bouharati3
1Optic and precision mechanics institute, Setif 1 University, Algeria
2LMFA, UMR CNRS 5509, ECL, INSA, Lyon, 36 Av. G. de Collongues, Ecully, 69130, France
3Laboratory of intelligent systems. Faculty of Technology, Setif 1 University, Algeria
Keywords: метод анемометрии по изображениям частиц, поперечные сечения возвышенностей, рециркуляция, турбулентность, PIV, two-dimensional hill, recirculation, turbulence

Abstract >>
This paper describes a laboratory study of the behavior of turbulent boundary layers in the presence of two-dimensional hills. Flow measurements of the developing turbulent boundary layer on a single hill and on two successive hills are performed in a wind tunnel. The mean and turbulent velocities are measured by PIV anemometry. The results provide a detailed description of the inner layers upstream and above the hills in the separation recirculation zones. The deduced mean and fluctuating velocity fields are compared for the flow in the presence of a single hill and two successive hills located on smooth and rough walls.

Numerical Study on an Unsteady Flow of an Immiscible Micropolar Fluid Sandwiched between Newtonian Fluids Through a Channel

M. Devakar, Ankush Raje, Shashikant Kumar
Visvesvaraya National Institute of Technology, Nagpur, 440010, India
Keywords: микрополярная жидкость, несмешиваемые жидкости, неустановившееся течение, горизонтальный канал, micropolar fluid, immiscible fluids, unsteady flow, horizontal channel

Abstract >>
This paper deals with an unsteady flow of a micropolar fluid sandwiched between Newtonian fluids through a horizontal channel. The governing time-dependent partial differential equations are solved numerically by using the Crank-Nicolson finite difference approach. The continuity of velocity and shear stress is considered at the fluid-fluid interfaces. It is observed that the fluid velocities increase with time; eventually, a steady state is reached at a certain time instant. The velocity decreases with increasing micropolarity parameter in the micropolar fluid region and remains almost unchanged in both Newtonian fluid regions.

Asymptotic Formula for the Spectrum of the Linear Problem Describing Periodic Polymer Flows in the Infinite Channel

A. M. Blokhin1,2, D. L. Tkachev1,2, A. V. Egitov1,2
1Sobolev Institute of Mathematics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Novosibirsk State University
Keywords: реологическая модель, полимерная среда, течение типа течения Пуазейля, устойчивость по Ляпунову, rheological model, polymer medium, flow type Poiseuille flows, Lyapunov stability

Abstract >>
A new rheological model (a modification of the Pokrovskii-Vinogradov model) is investigated. The model was shown by computational experiments to take into account the nonlinear effects occurring during melt flows and polymer solutions in regions with a complex geometry of the boundary. For the case where the main solution is an analogue of the Poiseuille flow in an infinite flat channel (viscoelastic polymer fluid considered), an asymptotic formula is obtained for the distribution of points of the spectrum of the linear problem. It is shown that small perturbations have the additional property of periodicity on the variable that runs along the axis of the channel.

Focusing of the Rarefaction Wave \\in a Thin Cavitating Fluid Layer with a Free Boundary

E. S. Zhuravleva, V. K. Kedrinskii
Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: ударная волна, волна разрежения, фокусировка, кавитационный процесс, shock wave, rarefaction wave, focusing, cavitation process

Abstract >>
A new method of focusing the rarefaction wave in a one-dimensional axisymmetric formulation is proposed. The method is based on shock wave generation initiated by motion of a piston coaxial with the axis of symmetry with a prescribed pulse profile for the maximum velocities of 20 to 100 m/s and the exponent decay constant up to 10 s. It is found that reflection of the shock wave from the free boundary generates a rarefaction wave propagating toward the axis of symmetry with increasing amplitude, and a cavitation zone is formed and developed behind the wave front.

Effect of Radiative Heat Transfer and Boundary Conditions on the Airflow and Temperature Distribution Inside a Heated Tunnel Greenhouse

S. Zeroual, S. Bougoul, H. Benmoussa
UniversitГ© de Batna 2, Batna, AlgГ©rie
Keywords: поток воздуха, температура, тепловое излучение, теплица, методы вычислительной гидродинамики, airflow, temperature, radiative heat transfer, tunnel greenhouse, CFD

Abstract >>
The airflow and temperature distribution in a heated tunnel greenhouse in the presence of a row of tomato plants owing to heat dissipation from heating pipes is numerically studied with the use of the Fluent-CFD software. The fully turbulent airflow in the greenhouse induced by buoyancy forces is modeled by using the κ-ε model. The radiative heat transfer is taken into account by using the model of discrete ordinates. Two types of boundary conditions expressing heat losses at the greenhouse cover are treated: pure convection and convection combined with thermal radiation.

Diffraction of a Plane Sound Wave on a Thermoelastic Sphere with a Discretely Inhomogeneous Coating

N. V. Larin
Tula State University, Tula, 300012, Russia
Keywords: дифракция звука, термоупругий шар, неоднородный термоупругий слой, diffraction of sound, thermoelastic sphere, inhomogeneous thermoelastic layer

Abstract >>
An analytical solution of the problem of the diffraction of a plane monochromatic sound wave on a sphere with a coating of several spherical layers is obtained using the equations of a linear coupled dynamic problem of the thermoelasticity of a homogeneous isotropic body. The results of calculations of the frequency and angular characteristics of the amplitude of a scattered acoustic field for a sphere with a multilayer coated and a coating with heterogeneity continuous across the thickness are given. It is shown that a continuously inhomogeneous thermoelastic coating can be modeled by a system of homogeneous thermoelastic layers. The effect of the thermoelasticity of the sphere materials and its discrete inhomogeneous coating on the scattering of sound was investigated.

High-power Pulse Magnetic Hydrodynamic Generator Fueled by a Solid (Powder) Propellant of a New Generation

A. G. Afonin1, V. G. Butov1, V. P. Panchenko2, S. V. Sinyaev1, V. A. Solonenko1, G. A. Shvetsov3, A. A. Yakushev2
1Research Institute of Applied Mathematics and Mechanics, Tomsk, 634050, Russia
2Troitsk Institute for Innovation and Fusion Research, Troitsk, 108840, Moscow region, Russia
3Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: самовозбуждающийся магнитогидродинамический генератор, металлизированное твердое плазмообразующее топливо, безударное сверхзвуковое течение, резистивная магнитная система, self-excited magnetohydrodynamic generator, plasma-forming metallized solid propellant, non-impact supersonic current, resistive magnetic system

Abstract >>
A method for designing a pulsed MHDG fueled by the combustion products of the modern Start-2 aluminized plasma-forming solid propellant was developed based on experimental and numerical studies of the characteristics and operating modes of a Sakhalin pulsed magnetohydrodynamic generator (MHDG) of the first generation with a capacity of more than 500 MW fueled by a solid powder propellant (SPP). This paper presents the results of calculations and optimization of the characteristics of the designed pulsed MHDG with a self-excited resistive “iron-free” magnetic system with an electrical power of more than 500 MW. The local, integral, and specific energy, weight, and size characteristics of this generator were determined. The stability parameters of supersonic flow during strong magnetohydrodynamic deceleration of the plasma of combustion products and the self-excitation time of the magnet were determined. The obtained characteristics of pulsed MHDG were compared with similar characteristics of MHDG fueled by the combustion products of the first-generation SPP. It is shown that the obtained values the energy, mass, and size characteristics of MHDG fueled by the Start-2 SPP substantially exceed the corresponding characteristics of the pulsed MHDG fueled by the new-generation SPP.

Determining the Thermo-Electro-Magneto-Elastic State of Multiply Connected Piecewise-Homogeneous Piezoelectric Plates

S. A. Kaloerov, E. S. Glushankov
Vasyl' Stus Donetsk National University, Donetsk, 83001, Ukraine
Keywords: линейный тепловой поток, пьезопластина, включения, температурные напряжения, напряженности и индукции электромагнитного поля, обобщенный метод наименьших квадратов, linear heat flux, piezoelectric plate, inclusions, temperature stresses, stresses and inductions of the electromagnetic field, generalized least squares method

Abstract >>
A method for studying the thermo-electro-magneto-elastic state of a multiply connected piecewise-homogeneous piezoelectric plate under the action of a linear heat flux is proposed. The solution of a problem using complex potentials and the generalized least squares method is reduced to solving a system of linear algebraic equations with respect to unknown expansion coefficients of functions into Laurent series and Faber polynomials. For the case of a plate with one inclusion, an exact analytical solution of the problem is obtained. The results of the numerical studies, which determine the effect of the electric and magnetic properties of the plate materials and inclusions and their location on the main characteristics of the thermo-electro-magneto-elastic state are described.

Investigation of Flow Characteristics and Heat Transfer Enhancement in a Nanofluid Flow in a Corrugated Duct

S. Sadripour
University of Shahreza, Shahreza, 8614956841, Iran
Keywords: канал, ребра, угол наклона, наночастицы SiO, турбулентное течение, коэффициент эффективности, corrugated duct, angle of the groove, SiO nanoparticle, turbulent flow, performance evaluation criterion

Abstract >>
A forced convection flow and heat transfer of a water-based nanofluid with SiO2 particles with different volume fractions and nanoparticle diameters in corrugated ducts with different shapes are numerically studied. The three-dimensional governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE technique. The effects of the nanoparticle diameter and shape on heat transfer is considered in the Reynolds number range 3000 ≤ Re ≤ 5000, and a uniform wall temperature is applied on the walls. The corrugated duct shape is optimized by the maximum performance evaluation criterion (PEC).

Elastic-Plastic Deformation of Flexible Plates with Spatial Frame Structures

A. P. Yankovskii
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: гибкие пластины, плоское армирование, пространственное армирование, теория Редди, динамический изгиб, упругопластическое деформирование, схема типа 'крест', flexible plates, flat reinforcement, spatial reinforcement, Reddy theory, dynamic bending, elastic-plastic deformation, leap-frog scheme

Abstract >>
A mathematical model for the elastic-plastic bending deformation of spatially reinforced plates is constructed based on a leap-frog numerical scheme. The elastic-plastic behavior of the component materials of the composition is described by the theory of flow with isotropic hardening. The low resistance of the composite plates to transverse shear is taken into account using Reddy's theory and the geometric nonlinearity of the problem using the von Karman approximation. The dynamic elastic-plastic bending deformation of flat and spatially reinforced metal composite and fiberglass rectangular plates under the action of an air blast wave is investigated. It is shown that for relatively thick plates, replacing a flat leap-frog reinforcement structure by a spatial one leads to a decrease in strain intensity in the binder (a few tens of percent for the metal composite structure and a few hundred percent for the fiberglass structure) and to a decrease in the pliability of the plate in the transverse direction (insignificant for the metal composite structure and a factor of almost 1.5 for fiberglass). It has been found that for relatively thin plates, replacing the flat reinforcement structure by the spatial one leads to a slight decrease in its pliability.

Torsion of Solid Rods with Account for the Difference between Tensile and Compressive Moduli of Elasticity

I. A. Banshchikova, A. Yu. Larichkin
Lavrent’ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: эксперимент, ползучесть, разносопротивляемость растяжению и сжатию, анизотропия, кручение стержней, титановый сплав, experiment, creep, difference between tensile and compressive moduli of elasticity, anisotropy, rod torsion, titanium alloy

Abstract >>
Experiments on tension and compression of solid solid samples cut out from a 60-mm thick plate of an Ti-Al-Sn-V alloy at a temperature of 700oC are used to determine that this alloy possesses small anisotropy and a difference between tensile and compressive moduli of elasticity. The approximations of the power law of creep are obtained for each series of these experiments and each direction in the plate. Two models based on the transformed space of stresses are used to simulate the torsion of solid solid samples. The models account for the difference between tensile and compressive moduli of elasticity. A series of experiments are carried out on the torsion of solid round rods cut out in the normal direction of the plate. It is shown that the computational and experimental results satisfactorily agree.

Entropy Interpretation of the Elastic-Plastic Strain Invariant

L. B. Zuev, A. G. Lunev, O. S. Staskevich
Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634055, Russia
Keywords: пластичность, упругая деформация, пластическая деформация, локализация, упругие волны, дефекты, дислокации, plasticity, elastic deformation, plastic deformation, localization, elastic waves, defects, dislocations

Abstract >>
An interpretation of the nature of the relationship between elastic and plastic strains, called the elastic-plastic strain invariant, is given which takes into account the change in the entropy of the system during autowave generation at the stage of linear strain hardening. It is shown that this approach consistently explains the nature of the invariant and its role in plasticity description

Determining the Stress-Strain State of Elastic-Plastic Solids with a Lateral Crack-Like Defect with the Use of a Model with a Linear Size

V. V. Glagolev, L. V. Glagolev, A. A. Markin
Tula State University, Tula, 300600, Russia
Keywords: трещина, упругопластические деформации, характерный размер, метод конечных элементов, crack, elastic-plastic deformations, characteristic size, finite element method

Abstract >>
A model of a physical section that describes stress-strain states in elastic-plastic solids weakened by cracks is proposed. The problem of plane deformation and the stress state of a solid of an infinite size of an arbitrary geometry, weakened by a physical section, is solved. It comes down to a system of two variational equations with respect to displacement fields in the parts of the solid bordering the interaction layer. For a material whose properties are close to those of a D16T alloy, the linear parameter introduced into the crack model is estimated, and the critical conditions of solids with lateral cracks in the case of a normal detachment are determined.

Stress Relaxation in cylindrical Glass-to-Metal Seals with Account for the Quality of a Junction Region

A. A. Burenin1,2, O. N. Lyubimova1, E. P. Solonenko1
1Far Eastern Federal University, Vladivostok, 690950, Russia
2Institute of Machine Science and Metallurgy, Far Eastern Branch, Russian Academy of Sciences, Komsomolsk-on-Amur, 681005, Russia
Keywords: технологические напряжения, стеклование, релаксационные процессы, technological stresses, glass transition, relaxation processes

Abstract >>
With account for a complex behavior of glass (the phenomenon of glass transition) and the degree of adhesion between glass and metal layers, a numerical-analytical method for calculating the evolution of a stress state of glass-metal composite during temperature treatment is proposed. The effect of relaxation processes in the glass - metal junction region on the technological and residual stresses in the composite is studied.

Nonlinear Delamination Analysis of Mulyilayered Functionally Graded Circular Shafts in Torsion

V. I. Rizov
University of Architecture, Civil Engineering and Geodesy, Sofia, 1046, Bulgaria
Keywords: многослойный круглый вал, функционально-градиентный материал, цилиндрическое расслоение, нелинейный материал, аналитическое решение, multilayered circular shaft, functionally graded material, cylindrical delamination, material nonlinearity, analytical solution

Abstract >>
Cylindrical delamination in a multilayered functionally graded circular shaft loaded in torsion is analyzed assuming a nonlinear mechanical behaviour of the material by using the Ramberg-Osgood equation. The shaft is made of an arbitrary number of adhesively bonded concentric layers of different thicknesses and material properties. In each layer, the material is functionally graded in both radial and longitudinal directions. A solution for the strain energy release rate is derived by analyzing the energy balance. The solution is used to perform parametric investigations of the delamination behaviour.

Research on Initial Pressure of Fracture in the Technique of Staged Fracturing of a Horizontal Well

Y. Lu1, V. V. Shelepov1, Z. Yang2, J. Liu3, J. Han1, X. Li2, J. Guo4
1Lomonosov Moscow State University, Moscow, 119991, Russia
2State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500, China
3Oil Production Plant 3 of Petro China Changqing Iolfield Company, Yinchuan, 750006, China
4Shanxi CBM Exploration and Development Subsidiary Company of SINOPEC, Jincheng, 048000, China
Keywords: угольно-метановый пласт, горизонтальная скважина, кливаж, давление, многоступенчатое разрушение, coalbed methane, horizontal well, cleats, multifracture

Abstract >>
Based on the stress distribution model of a horizontal well, the calculation model on the fracture pressure of the coalbed methane (CBM) horizontal well is developed. This model deals not only with initiation of the matrix fracture, but also of shear and open fractures. The effects of the cleat parameters and spatial orientation of the well on the fracture character are considered.

Presenting a Model for Prediction of Crack Growth under Simultaneous Creep and Corrosion

M. Zarkesh
Faculty of Mechanical Engineering, University Islamic Azad, Dashtestan, 7561888711, Iran
Keywords: рост трещины, функция ползучести, наследственная теория ползучести, коррозия, критическая длина трещины, crack growth, creep function, hereditary crack theory, corrosive environment, critical length of the crack

Abstract >>
The process of crack growth in parts subjected to hot fluids is studied. The high temperature of the fluid activates the creep and corrosion processes. The hereditary creep theory is used for calculating the stress field. A creep function is introduced to determine the forces acting on the crack at the crack concealment and crack growth stages. The resisting force is calculated by using the Rabotnov method of accumulated small fractures in the crack region. The effect of the corrosive environment is considered in the calculations by using the penetration function. The resultant equations are solved by using the MATLAB software. The effects of the initial crack length and the applied stress on the crack growth curve are investigated.

Creating a Coating from the Titanium-Aluminum Intermetallic Compound by the Cold Spray Technology

S. P. Kiselev1,2, N. S. Ryashin1, E. A. Maksimovskii3, V. P. Kiselev1, S. V. Klinkov1, V. F. Kosarev1, A. A. Filippov1, V. S. Shikalov1
1Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Novosibirsk State Technical University, Novosibirsk, 630092, Russia
3Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: интерметаллид титан - алюминий, уравнение диффузии, метод молекулярной динамики, расплав алюминия, метод холодного газодинамического напыления, радиальное сопло, сверхзвуковое течение, Titanium-aluminum intermetallic compound, diffusion equation, molecular dynamics method, aluminum melt, cold spray, radial nozzle, supersonic flow

Abstract >>
Results of experimental and numerical investigations of the process of creating coatings from the titanium-aluminum intermetallic compound by using an additive method are presented. It is demonstrated that the process of intermetallic compound formation is limited by the rate of titanium dissolution and diffusion in the aluminum melt. The proposed method can be applied for hardening titanium plate surfaces during their exploitation at high temperatures and pressures.

Effect of Surface Layer Damage on Acoustic Anisotropy

A. S. Semenov, V. A. Polyanskii, L. V. Shtukin, D. A. Tretyakov
St. Petersburg Polytechnic University of Peter the Great, St. Petersburg, 195251, Russia
Keywords: акустическая анизотропия, эффект поверхностного слоя, эксперимент, моделирование, тензор поврежденности, acoustic anisotropy, surface layer effect, experiment, simulation, damage tensor

Abstract >>
Data on the speeds of longitudinal and transverse waves are used to derive relations for the principal values of the damage tensor proposed. The relationship between acoustic anisotropy and the main values of the damage tensor are established. The distribution pattern of local speeds and damage along the thickness of the specimen is studied. It is shown that damage is localized in a narrow surface layer, with local damage maxima far exceeding the average damage value

Basic Test Rig for Studying Oscillating Fluid Flows

A. M. Sorokin1, A. V. Boiko1,2, A. A. Tulupov3,4, A. P. Chupakhin3,5
1Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
2Tyumen' State University, Tyumen', 625003, Russia
3International Tomography Center, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
4Novosibirsk State University, Novosibirsk, 630090, Russia
5Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090, Russia
Keywords: пульсирующие течения, каналы, гемодинамика, автоматизированный измерительный комплекс, oscillating flows, channels, hemodynamics, automated measurement system

Abstract >>
A test rig designed for studying oscillating fluid flows in channels is described. The shape of pressure oscillations is defined by displacements of a piston whose motion is controlled by a stepping motor, and the minimum step of the piston is 6 μm.