فهرست مطالب

Applied and Computational Mechanics - Volume:5 Issue:5, 2019
  • Volume:5 Issue:5, 2019
  • تاریخ انتشار: 1398/07/09
  • تعداد عناوین: 15
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  • MD Shamshuddin *, Thumma Thirupathi, P.V. Satya Narayana Pages 816-826
    Computational and mathematical models provide an important compliment to experimental studies in the development of solar energy engineering in case of electro-conductive magnetic micropolar polymers. Inspired by further understanding the complex fluid dynamics of these processes, we examine herein the non-linear steady, hydromagnetic micropolar flow with radiation and heat source/sink effects included. The transformed non-dimensional governing partial differential equations are solved with the R-K fourth order with shooting technique subjected to appropriate boundary conditions. The characteristics of the embedded parameters are obtained and presented through graphs. Velocity and microrotation of the fluid decreased with enhancing values of material parameter and suction/injection parameter. Electric field parameter has ability to enhance velocity, but temperature shows opposite behaviour. Microrotation increases for both magnetic field and surface temperature parameters.
    Keywords: Micropolar fluid, Heat source, sink, Stretching sheet, Partial slip, Surface heat flux boundary conditions
  • Abdul Rauf * Pages 827-839
    Unsteady oscillatory flow of generalized Burgers’ fluid in a circular channel tube in the porous medium is investigated under the influence of time-dependent trapezoidal pressure gradient given by an infinite Fourier series. An exact analytical expression for the solution for the fluid velocity and the shear stress are recovered by using the similarity arguments together with the integral transforms. The solution is verified with a semi-analytical solution obtained by employing the Stehfest's method. Using the software Mathcad, numerical calculations have been carried out, and results are presented in graphical illustrations in order to analyze the effects of various fluid parameters on the fluid motion. As expected, with the increase in the permeability of the porous medium, the drag force decreases, which results in an increase in the velocity profile for all kinds of fluid models (a generalized Burgers’ fluid, a Burgers’ fluid, a Maxwell fluid, and an Oldroyd-B fluid). Moreover, it has been observed that the material constants of the generalized Burgers’ fluid, as well as the Burgers’ fluid, are other important factors that enhance the flow velocity performance of the fluid. The velocity-time variation for the generalized Burgers’ fluid, the Oldroyd-B fluid, and the Newtonian fluid is similar to the trapezoidal waveform, whereas it is different for the Burgers’ and Maxwell fluid.
    Keywords: Oscillating motion, Porous medium, Trapezoidal pressure gradient, Generalized Burgers’ fluid, Analytical, semi-analytical solution
  • Adetayo Eegunjobi *, O.D. Makinde Pages 840-848
    Analysis of intrinsic irreversibility and heat transfer in a buoyancy-driven changeable viscosity liquid along an incline heated wall with convective cooling taking into consideration the heated isothermal and isoflux wall is investigated. By Newton’s law of cooling, we assumed the free surface exchange heat with environment and fluid viscosity is exponentially dependent on temperature. Appropriate governing model equations for momentum and energy balance with volumetric entropy generation expression are obtained and then transformed using dimensionless variables to form set of nonlinear boundary valued problem. Using shooting method with Runge-Kutta-Fehlberg integration scheme, the model is numerically tackled. Pertinent results for the fluid velocity, temperature, skin friction, Nusselt number, entropy generation rate and Bejan number are obtained and discussed.
    Keywords: Inclined plane, MHD liquid film, Isothermal wall, Isoflux wall, Convective cooling, Entropy generation
  • Mumukshu Trivedi, O. Otegbeye, Md. S. Ansari *, Sandile S. Motsa Pages 849-860
    Present study explores the effect of Hall current, non-linear radiation, irregular heat source/sink on magnetohydrodynamic flow of Casson nanofluid past a nonlinear stretching sheet. Viscous and Joule dissipation are incorporated in the energy equation. An accurate numerical solution of highly nonlinear partial differential equations, describing the flow, heat and mass transfer, by a new Spectral Paired Quasi-linearization method is obtained and effect of various physical parameters such as hall current parameter, radiation parameter, Eckert number, Prandtl number, Lewis number, thermophoresis parameter and Brownian motion parameter on the thermal, hydro-magnetic and concentration boundary layers are observed. The analysis shows that variation of different thermo-magnetic parameter induces substantial impression on the behaviour of temperature and nanoparticle distribution. Thermal boundary layer is greatly affected by conduction radiation parameter.
    Keywords: Magnetic field, Casson Nanofluid, Mixed convection, Non-uniform heat source, sink, Paired quasi-linearization method (PQLM)
  • Houda Salmi *, Khalid El Had, Hanan El Bhilat, Abdelilah Hachim Pages 861-874
    The present work investigates the effect of the elliptical three-dimensional (3D) cracks on a pipe with thickness transition, considering internal pressure. Level sets were defined using the extended finite element method (XFEM), the stress intensity factors (SIFs) of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition. The results show that the XFEM is an effective tool for modeling crack in pipes. A pressurized pipe with thickness transition is more sensitive to the feature compared to the straight pipe. Parameters of the transition zone have an influence on stress intensity factors. Quantification of the SIFs associated with cracks in the transition zone of pipes with thicknesses is performed.
    Keywords: Pressurized equipment, Pipe with thickness transition, Three-dimensional crack, XFEM, SIF, Level set
  • J.C. Monge, J.L. Mantari *, J. Yarasca, R.A. Arciniega Pages 875-899
    This paper presents a static analysis of laminated composite doubly-curved shells using refined kinematic models with polynomial and non-polynomial functions recently introduced in the literature. To be specific, Maclaurin, trigonometric, exponential and zig-zag functions are employed. The employed refined models are based on the equivalent single layer theories. A simply supported shell is subjected to different mechanical loads, specifically: bi-sinusoidal, uniform, patch, hydrostatic pressure and point load. The governing equations are derived from the Principle of Virtual displacement and solved via Navier-Type closed form solutions. The results are compared with results from Layer-wise solutions and different higher order shear deformation theories available. It is shown that refined models with non-polynomial terms are able to accurately predict the through-the-thickness displacement and stress distributions maintaining less computational effort compared to a Layer-wise models.
    Keywords: Shell, Laminated composite, Carrera Unified Formulation (CUF), Doubly-curvature
  • Milad Esmaeili, Yaghoub Tadi Beni * Pages 900-917
    In this paper, the buckling and vibration behaviour of functionally graded flexoelectric nanobeam is examined. The vibration and buckling formulations of functionally graded nanobeam are developed by using a new theory that’s presented exclusively for flexoelecteric nano-materials. So by considering Von-Karman strain and forming enthalpy equation based on displacement, polarization and electric potential, electromechanical coupling equations are developed base on Hamilton’ principle. By considering boundary condition of simply support and clamped-clamped and also Euler-Bernoulli beam model, pre-buckling, buckling and the vibration behavior of functionally graded nanobeam affected by flexoelectric will be investigated.
    Keywords: Flexoelectric effect, Functionally graded nanobeam, Piezoelectric effect, Size-dependent, Euler-Bernoulli beam model
  • Rajab A. Malookani *, Sanaullah Dehraj, Sajad H. Sandilo Pages 918-925
    Transversal vibrations of an axially moving string under boundary damping are investigated. Mathematically, it represents a homogenous linear partial differential equation subject to nonhomogeneous boundary conditions. The string is moving with a relatively (low) constant speed, which is considered to be positive.  The string is kept fixed at the first end, while the other end is tied with the spring-dashpot system. The asymptotic approximations for the solution of the equations are obtained by application of two time-scale perturbation technique and the characteristic coordinates method. The vertical displacement of the moving system under boundary damping is computed by using specific initial conditions. It is shown that how the introduced damping at the boundary may affect the vertical displacement of the axially moving system.
    Keywords: Axially moving string, Boundary damping, Two time-scale perturbation, Characteristic coordinates
  • Anand Mandi *, Santimoy Kundu, Prasenjit Pati, Prakash Chandra Pal Pages 926-934
    Love-type wave generation in a fiber-reinforced medium placed over an inhomogeneous orthotropic half-space is analysed. The upper and lower boundary surfaces of the fiber reinforced medium are periodically corrugated. Inhomogeneity of half-space is caused by variable density and variable shear modules. Displacement components for layer and half-space are derived by applying separable variable technique. Dispersion relation for Love wave is obtained in closed form. Numerical calculations for the achieved dispersion equation are performed. In the numerical examples, the main attention is focused on the effect of corrugation investigation, reinforced parameters and inhomogeneity on the relations between wave number and phase velocity.
    Keywords: Love wave, Fiber-reinforced, Inhomogeneous, Corrugation
  • Akuro Big, Alabo *, Chinwuba Ossia Pages 935-950
    This paper presents a fixed-end two-mass system (TMS) with end constraints that permits uncoupled solutions for different masses. The coupled nonlinear models for the present fixed-end TMS were solved using the continuous piecewise linearization method (CPLM) and detailed investigation on the effect of mass-ratio on the TMS response was conducted. The investigations showed that increased mass-ratio leads to decreased oscillation frequency and an asymptotic response was obtained at very large mass-ratios. Theoretical solutions to determine the asymptotic response were derived. Also, it was observed that distinct responses can be obtained for the same mass-ratio depending on the mass combination in the TMS. The present fixed-end TMS and the analyses presented give a broader understanding of fixed-end TMS.
    Keywords: Continuous piecewise linearization method, Two-mass system, Cubic Duffing oscillator, Coupled nonlinear vibration
  • Ravi Rajesh *, Y. Rajasekhara Gowd Pages 951-963
    This paper deals with a theoretical investigation of heat and mass transfer with thermal radiation analysis on hydromagnetic peristaltic Prandtl fluid model with porous medium through an asymmetric tapered vertical channel under the influence of gravity field. Analytical results are found for the velocity, pressure gradient, pressure rise, frictional force, temperature and concentration. The influence of varied governing parameters is discussed and illustrated diagrammatically through a set of figures. It can be seen that the axial velocity enhances with an increase in gravity parameter. It is observed that the temperature of the fluid reduces within the tapered asymmetric vertical channel by an increase in thermal radiation parameter. Blood flow in concentration profile increases with an increase in thermal radiation parameter. It is worth mentioning that the rate of pumping rises in all the four regions, i.e. retrograde pumping region, peristaltic pumping region, free pumping region and an augmented region with an increase in Prandtl fluid parameter.
    Keywords: Thermal radiation, MHD, Porous medium, Temperature, Mass transfer, Gravity filed
  • Ammar Kazemi Jouybari *, Arash Mirabdolah Lavasani Pages 964-975
    This paper tries to achieve a solution for problems that concern condensation around a flat plate, circular and elliptical tube in by numerical and analytical methods. Also, it calculates entropy production rates. At first, a problem was solved with mesh dynamic and rational assumptions; next it was compared with the numerical solution that the result had acceptable errors. An additional supporting relation is applied based on the characteristic of the condensation phenomenon for condensing elements. As it is shown here, due to higher rates of heat transfer for elliptical tubes, they have more entropy production rates, in comparison to circular ones. Findings showed that the two methods were efficient. Furthermore, analytical methods can be used to optimize the problem and reduce the entropy production rate.
    Keywords: Entropy rate, Analytical solution, Numerical solution, Condensation
  • Behnam Fallah, Saeed Dinarvand *, Mohammad Eftekhari Yazdi, Mohammadreza Nademi Rostami, Ioan Pop Pages 976-988
    This study intends to semi-analytically investigate the steady 3D boundary layer flow of a SiC-TiO2/DO hybrid nanofluid over a porous spinning disk subject to a constant vertical magnetic field. Here, the novel attitude to single-phase hybrid nanofluid model corresponds to considering nanoparticles and base fluid masses to compute solid equivalent volume fraction, solid equivalent density, and also solid equivalent specific heat at constant pressure. The basic PDEs are transformed into dimensionless ODEs using Von Kármán similarity transformations, which are then solved numerically using bvp4c function. Results indicate that mass suction and magnetic field effects diminish all hydrodynamic and thermal boundary layer thicknesses. Finally, a significant report is presented to investigate quantities of engineering interest due to governing parameters’ effects.
    Keywords: 3D boundary layer flow, Single-phase hybrid nanofluid, Spinning disk, Semi-analytical modeling, Diathermic oil
  • Jaideep Dutta, Balaram Kundu * Pages 989-997
    The importance of the slip flow over the no-slip condition is widely accepted in microscopic scaled domains with the direct impact on microfluidic and nanofluidic systems. The popular Navier Stoke’s (N-S) flow model is largely utilized with the slip flow phenomenon. In the present study, the finite integral transform scheme along with the shift of variables is implemented to solve the equation of motion of second grade fluid having third-order mixed partial derivative term. The velocity over the flow regime is studied with both the slip and no-slip boundary conditions for Newtonian and non-Newtonian characteristics by considering the generalized Couette flow. The impact of the pressure gradient and flow time on the velocity is investigated analytically. The output of the present research reveals that due to the slip flow velocity randomly varies at the vicinity of wall surface and such nature hasn’t been found for the no-slip condition. The validation of the present work was done by comparison with the published work and the numerical values, and it shows well verified.
    Keywords: Second grade fluid, Exact solution, Couette flow, Slip condition, Non-Newtonian fluid
  • Ioannis N. Tsiptsis *, Olga E. Sapountzaki Pages 998-1022
    In this research effort, the generalized warping and distortional problem of straight or horizontally curved composite beams of arbitrary cross section, loading and boundary conditions is presented. An inclined plane of curvature is considered. Additionally, the stiffness of diaphragmatic plates has been introduced in the formulation in order to compare with the case where rigid diaphragms are assumed. Isogeometric tools (NURBS) are employed in order to obtain the results for the 1D formulation and 3D shell models are developed in FEM commercial software for composite cross sections with diaphragms. The number of intermediate diaphragms according to bridges design specifications is compared to the analyzed diaphragmatic arrangements in order to assess the overall structural behavior of bridges decks. For this purpose, examples of curved beam models with open or closed cross sections and various arrangements of diaphragms have been studied.
    Keywords: Higher-Order-Beam-Theories, Finite element method-FEM, Distortion, Warping, Guidelines, Diaphragms