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The similarity solution for Darcy free convection about an isothermal vertical cone with fixed apex half angle, pointing downward in a nanofluid saturated porous medium, has been made. It is assumed that the medium contains gyrotactic microorganisms along with nanoparticles and the cone is subjected to concentration of nanoparticles and density of motile microorganisms. The effects of Brownian motion...
The aim of this article is to present an efficient dynamical model for simulating flapping robot performance employing the bond graph approach. For this purpose, the complete constitutive elements of the system under investigation, including the main body and accessories, flapping mechanism, flexible wings and propulsion system consisting of a battery, DC motors and gear boxes, are considered. A complete...
AC-pulsed gas metal arc welding may be a good option for applications that require low heat input and high productivity. The introduction of a negative polarity period assists in obtaining such characteristics, due to an increase in the wire melting rate for this polarity. The main difficulty related to the use of this version of the process is in selecting the correct welding parameters. In the scope...
The unsteady viscous flow and heat transfer in the vicinity of an unaxisymmetric stagnation-point flow of an infinite moving cylinder with time-dependent axial velocity and non-uniform normal transpiration $$ U_{0} \left( \varphi \right) $$ U 0 φ are investigated. The impinging free stream is steady with a strain rate $$ \bar{k} $$ k ¯ . A reduction of the Navier–Stokes...
Cable-stayed bridges and guyed towers are examples of structures extensively used in Civil Engineering. The uniform tension in the cable may change during service life due to various causes. Thus, uncertainty studies appear desirable to provide information about the effect of the parameter variations on the structure dynamics. The non-linear dynamic behavior of a cable-beam system, as a simplified...
In this study, the dual-phase-lag (DPL) heat conduction model is applied to study the non-Fourier heat transfer in a thermal barrier coating (TBC) structure subjected to heat flux on the exterior of the coating. An efficient numerical scheme involving the hybrid application of the Laplace transform and control volume methods in conjunction with hyperbolic shape functions is used to solve the hyperbolic...
This paper presents a new void fraction predictive method for two-phase gas–liquid flows inside tubes for horizontal and vertical upward flows based on the principle of minimum kinetic energy. Non-uniformities of the velocity profiles are taken into account in the development of the method through empirical factors defined by the momentum coefficients ratio. A regression analysis to correlate the...
Internal combustion engines inherently demand startup assistance to perform its autonomous functioning. Nevertheless, the common solution over more than one century has been the electric starter motor, for both Otto and diesel cycles. The dynamic coupling system defined herein as the mechanical connection between the internal combustion engine and the starter motor has not evolved considerably since...
The effects of non-Newtonian power-law fluids on the unsteady unconfined fluid flow characteristics of an equilateral triangular prism are investigated for Reynolds number (Re) ranging from 50 to 150 and power-law index (n) ranging from 0.4 to 1.8. The flow field around a triangular prism is represented by streamline contours. The output parameters such as root-mean-square values of lift and drag...
The paper discusses the results obtained using an in-house developed finite volume code for three-dimensional, unstructured, adaptive meshes to simulate inviscid and viscous flows. A fully explicit, second-order accurate, five-stage, Runge–Kutta time-stepping scheme is used to perform the time march of the flow equations. Two different forms for flux calculation on the volume faces are implemented...
Experience indicates that there are many operating pressure vessels with a lack of fusion defects in their nozzle welds. A fitness for service assessment of such flaws is often required. Due to geometrical complexity, finite element analysis is needed, but inserting a 3D crack mesh in such analysis can be complex and time consuming. To overcome this issue, a C/C++ program capable of generating 3D...
The present study analyzes the process of fragmentation of a liquid volume into a cloud of droplets, a well-known phenomenon usually denoted as primary atomization. The experimental work was performed in a single-orifice pressure-swirl atomizer. For the first time, a transition was observed in the droplet size distribution function (DSDF) that transforms from a Nukiyama–Tanasawa type to a power law...
Since necking in some novel processes such as hydroforming and incremental forming can occur at locations where in addition to the in-plane stresses normal and through thickness shear stresses are exerted on the sheet metal, the plane stress assumption is not proper for predicting forming limits in these processes. Consequently in this research, conventional Marciniak-Kuczynski formability model has...
Despite its significant effect on the weight and dynamic performance of a gear system, the topology of the gear blanks, including the geometry and dimensions of the hub, the web and the spokes, has not been systematically studied. The occasional investigations of the subject have been mainly experimental and/or based on simplifying assumptions. This paper presents a simulation-based approach to the...
Recently, more research have been conducted on the analysis of the vibration response of rotors, so that new techniques, which are used to characterize the dynamic response of rotating machines, have been developed to aid and predict the lifespan of such systems. One of the vibration management techniques in rotating systems is the monitoring of stiffness and damping parameters of the bearings and...
In some types of hermetic refrigeration reciprocating compressors, the oil circulation pattern inside the crankcase produces an oil falling film on the inner wall of the compressor shell. The conjugate heat transfer between the shell and the oil affects the heat dissipation from the internal components to the external environment and, consequently, the compressor thermal profile. A differential model...
In this paper, a novel modified version of the implicit–explicit integration scheme (IMPL-EX) proposed by Oliver (Comput Methods Appl Mech Eng 197:1865–1889, 2008) is presented. This modified approach has as its main difference with respect to the standard IMPL-EX the choice of internal variables to be updated. In the modified approach what is updated are the plastic strain tensor components, instead...
This study investigates the effects of computed tomography (CT) parameters on the quality and size of the reverse triangular surface model with an objective of obtaining an accurate 3D triangular surface model of complex-shaped customized objects for reverse engineering and many other applications such as surgical planning and finite element analysis. For this purpose, the fibula of a human knee joint...
The relentless pursuit of greater productivity and lower maintenance costs, allied to the development of optimized products, has led to increasing concerns regarding fatigue failure. This scenario reinforces the importance of monitoring dynamic stress and strain in structures and machines subjected to vibration. For this purpose, several methods that use vibration parameters have been developed to...
Combustion, one of the main forms of energy production nowadays, is a complex phenomenon in which turbulent flow, chemical reactions, different phases and heat transfer phenomena can interact. A better understanding of these interactions is essential to improve existing combustion systems and develop new ones. The aim of this work was to study the interaction of turbulent combustion with thermal radiation...
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