International Journal of Mechanics

ISSN: 1998-4448
Volume 12, 2018

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of NAUN Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

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Volume 12, 2018

Title of the Paper: Flow Structure of the Transverse Jet Interaction with Supersonic Flow for Moderate to High Pressure Ratios


Authors: Asel Beketaeva, Altynshash Naimanova

Pages: 88-95

Abstract: The vortex structures behind the transverse jet in a supersonic flow for moderate to high pressure ratios are studied. Numerical simulation is performed using the three-dimensional Favre-averaged Navier–Stokes equations coupled by the turbulence model which are solved by the algorithm based on the high-order non-oscillatory (ENO) scheme. The simulations correctly captured primary vortices: the well-known two counter-rotating vortices, the primary upstream vortex and the secondary upstream vortex, the horseshoe vortex, the pair of vortex in a separation region, and one pair of vortices appeared due to the interaction of the jet passing through the Mach disk, two pairs of vortices formed due to an overflow above the jet. The additional two vortices are found localized near the wall in the region behind the jet.

Title of the Paper: The Study of the Mixing Layer Particles Distribution in Dependence on the Convective Mach Numbers


Authors: Altyn Makasheva, Altynshash Naimanova

Pages: 79-87

Abstract: The numerical studies of the quasi two-dimensional supersonic turbulent gas-particle mixing layer are performed using the 2D-DNS (Direct Numerical Simulations). The system of Navier-Stokes equations of a multi-species flow is solved using the ENO scheme of a third-order accuracy. The dispersion of the particles is simulated by the Lagrangian method following their trajectories in the mixing layer. The study focuses on the roles of the large-scale vortex structures in a particle dispersion dependence on the Stokes numbers and convective Mach numbers.

Title of the Paper: Experimental Determination of Aeroelastic Derivatives for a Small-Scale Bridge Deck


Authors: M. Cassaro, E. Cestino, G. Frulla, P. Marzocca, M. Pertile

Pages: 67-78

Abstract: A heaving and pitching two degrees of freedom bridge-deck sectional model apparatus representative of a long-span bridge was designed, built, and tested in the wind tunnel to acquire measurement of aeroelastic derivatives. The main objective of this study was the experimental validation of the procedure to compute the aeroelastic derivatives based on the Iterative Least Square Method identification technique. A good correspondence was found between the flutter derivatives experimentally extracted from the model, and the corresponding reference values, which have been analytically derived from the Theodorsen’s theory. A simulation model in MATLAB/Simulink® environment, useful for future control laws applications, was also developed and validated by real experimental results.

Title of the Paper: Frequency Analysis of Partially-Filled Rectangular Water Tank


Authors: K. Kotrasova, E. Kormanikova

Pages: 59-66

Abstract: This paper deals with experimental studies of sloshing of liquid in partially filled container subjected to external excitation horizontal harmonic motion. The theoretical background of fluid response on rectangular tank due to horizontal acceleration of tank bottom, impulsive and convective (sloshing) pressure and the fluid natural frequencies is presented in paper. The dynamic behavior of fluid filled rectangular container was monitored and was evaluated in realized experiment. The resulting peak slosh heights for various excitation frequencies and amplitudes in fluid filled rectangular tank are compared with the fluid natural frequencies.

Title of the Paper: Complete Study for Solving Navier-Lame Equation with New Boundary Condition Using Mini Element Method


Authors: Ouadie Koubaiti, Jaouad El-Mekkaoui, Ahmed Elkhalfi

Pages: 46-58

Abstract: The objective of our article is to solve the Navier-Lame equation with a new boundary CA;B condition using the mixed finite elements method . We compare between minielement method and the ordinary finite element method by the other side. We compute the displacement and its divergence simultaneously by using an extra unknown. We prove the existence and uniqueness of the weak and discrete solution by proving the discrete inf-sup and coerciveness conditions. We expose two ways of comparison, that the first way we calculate the rate α called speed of convergence found by each of the two numerical methods, all this will be done by the use of the linear regression. An analytical example is used to validate the accuracy, convergence and robustness of the present mixed finite elements method for elasticity. In order to evaluate the performance of the method, and to confirm our method, the numerical results of mini element method are compared with others coming from commercial code like Abaqus system.

Title of the Paper: Post-Newtonian Equations for Free-space Laser Communications between Space-based Systems


Authors: Jose M. Gambi, Maria L. Garcia del Pino, Jonathan Mosser, Ewa B. Weinmüller

Pages: 38-45

Abstract: The purpose of this paper is to show that the equations for relative motions derived from the two systems of post-Newtonian equations presented here, allow to increase the acquisition, pointing and tracking accuracy when compared to the Newtonian equations aimed to describe free-space laser communications between Low Earth Orbit (LEO) satellites, so as between LEO and Medium Earth Orbit (MEO), and Geostationary Earth Orbit (GEO) satellites. The equations discussed in this work are similar, but not equivalent to those proposed for space debris removal, i. e. in the context of spacebased systems to throw middle size LEO debris objects into the atmosphere via laser ablation. In fact, the present equations are computationally much more affordable because the aim is now less demanding, and so they result from subtractions within each post-Newtonian system here provided.

Title of the Paper: Estimation of Dynamic Behavior and Energy Efficiency of Thrust Hybrid Bearings with Active Control


Authors: Alexander Babin, Sergey Majorov, Leonid Savin

Pages: 32-37

Abstract: The present paper considers analysis of world tendencies of application of bearings with feedback control systems in various types of rotor machines. A possibility of qualitative improvement of operational characteristics has been highlighted for bearings with integrated additional functions of automated diagnostics and active control of geometric, rheological and force parameters. The present paper features a mathematical model, its implementation in a form of an algorithm, and numerical results including pressure and temperature distribution in a bearing in question, load capacity and rotor’s axial trajectories. A quality index has been formulated for thrust tapered land hybrid bearings with a central feeding chamber that is based on a combination of minimum power loss due to friction and stability of motion of a rotor. Various combinations of roughness and axial gaps have been taken into account.

Title of the Paper: Influence of Non-Linear Behavior on Seismic Response Parameters


Authors: Rita Greco, Alessandra Fiore, Ivo Vanzi

Pages: 19-31

Abstract: This paper deals with the effects of post-yielding stiffness on the response of non-linear structural systems under seismic actions. In detail, two hysteretic models are considered: a bilinear plastic model, representing structures that exhibit strain hardening characteristics, and an elastic-perfectly-plastic model, widely adopted in design codes. For these models, a parametrical study is carried out to assess the influence of post-yielding stiffness ratio on some non-linear response quantities, such as the response modification factor, the ductility demand and the damage index. The analysis is developed on a SDOF system subject to El Centro earthquake and demonstrates that the elastic-plastic constitutive law is excessively conservative to evaluate structural deformations. Finally the study provides useful information also from an energetic point of view.

Title of the Paper: Axisymmetric Deformation Analysis of Thick-Walled Cylinders and Rotating-Disks Using an Improved Adomian Decomposition Method


Authors: Safa Bozkurt Co┼čkun, Zuhal Elif Kara

Pages: 14-18

Abstract: In this study, a problem arising in advanced engineering mechanics governed by a singular differential equation is solved using an improved Adomian decomposition method. The technique was previously used in literature for the solution of two-point singular boundary value problems in applied mathematics. Authors extend the use of the mathematical technique to presented problem and the results show that improved Adomian decomposition method can be successfully used in the axisymmetric deformation and stress analysis of thick-walled cylinders and rotating disks.

Title of the Paper: Model of Pressure Losses in Pipes During the Transport of Heavy Oil with 11 API Gravity


Authors: Manuel A. Falconi, Enrique T. Tamayo, Héctor L. Laurencio, Jorge P. Vega, Elvis P. Gualotuña, Edwin R. Grijalva, Luís Grijalva Campana

Pages: 8-13

Abstract: During the transport of heavy oils by pipes, there are difficulties related to their high viscosity with non-Newtonian behavior, directly affecting the performance of the transport facilities, because of the inaccuracies of the calculation methodologies. In the present work it obtain a mathematical model that describes the pressure variations for non-Newtonian oil flow in pipes; obtained from the limitations of methodologies and correlations, that allows the evaluation of the simultaneous effects of the viscous force and of mixing in the laminar and turbulent regime during the transport of heavy oils by pipes. Equation 15 is the generalized theoretical model for the calculation of pressure variations in the transport of heavy crude oil by pipeline. It takes into account the variation of temperature during transport, the effects of viscous friction, and the effects of mixing between flow layers. The values of the flow index for the transport of heavy oil of 11ºAPI by pipes oscillates between 0,917 and 0,929 in function of the temperature values that vary between 29 oC and 69.8 oC. The consistency index varies between 13.55 Pa.s and 1.46 Pa.s for the same temperature range.

Title of the Paper: Numerical Study of Disperse Materials Process in a Continuous-Flow Plasma Reactor


Authors: Issakhov A. A., Urmashev B. A.

Pages: 1-7

Abstract: The paper presents a numerical study of the temperature propagation in the direct-flow plasma reactor, which is solved by the compressible Navier - Stokes equations that is approximated by finite volume method, the numerical algorithm based on the SIMPLE method. In the numerical algorithm of the equation system can be divided into four stages. The first stage is that the transfer of momentum carried out only by convection and diffusion. The intermediate velocity field is solved by the solution of the differential velocity gradient equation with the Green-Gauss Cell Based scheme. For the pressure field is applied PRESTO numerical scheme. In a third step it is assumed that the transfer is carried out only by the pressure gradient. The fourth step of the equation is solved for the energy transport equation as well as the momentum equations by the Green-Gauss Cell Based scheme. The algorithm is parallelized on high-performance systems. With this numerical algorithm was obtained numerical results of temperature distribution in a continuousflow plasma reactor. Numerical modelling allows us to give a more precise description of the processes that have been identified and studied theoretically and can reveal new physical phenomena processes that are not yet available, seen in experimental studies. Simulation results show that the constructed numerical model provides the necessary accuracy and stability, which should accurately describe the process during the time interval.