Search for: eulerian-analysis
0.006 seconds

    Excess sensitivity and borrowing constraints: Evidence from Iranian households

    , Article Economics of Transition and Institutional Change ; Volume 28, Issue 1 , 2020 , Pages 137-160 Einian, M ; Nili, M ; Sharif University of Technology
    John Wiley and Sons Inc  2020
    In contrast to the findings of simple rational expectations permanent income hypothesis models, empirical studies show that income changes can help predict consumption change. This is dubbed as excess sensitivity in the macroeconomic literature. We use Iranian household data to investigate the excess sensitivity using civil servant status as a proxy for borrowing constraints. We observe that the excess sensitivity is different among different panels. Much less excess sensitivity is observed for government employees who have better access to finance due to the structure of the labour market and banking system in Iran. Our proxy variable to divide data, which is the working status of the head... 

    Wave dispersion under finite deformation

    , Article Wave Motion ; Volume 50, Issue 3 , April , 2013 , Pages 374-388 ; 01652125 (ISSN) Abedinnasab, M. H ; Hussein, M. I ; Sharif University of Technology
    We derive exact dispersion relations for axial and flexural elastic wave motion in a rod and a beam under finite deformation. For axial motion we consider a simple rod model, and for flexural motion we employ the Euler-Bernoulli kinematic hypothesis and consider both a conventional transverse motion model and an inextensional planar motion model. The underlying formulation uses the Cauchy stress and the Green-Lagrange strain without omission of higher order terms. For all models, we consider linear constitutive relations in order to isolate the effect of finite motion. The proposed theory, however, is applicable to problems that also exhibit material nonlinearity. For the rod model, we... 

    Numerical assessment of a double step integration algorithm for J 2 plasticity with Armstrong-Frederick evolution of back stress

    , Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1168-1179 ; 10263098 (ISSN) Jahanshahi, M ; Sharif University of Technology
    In this work a double step algorithm is presented for the integration of equations governing the behavior of von Mises material in plastic limit. The isotropic and kinematic hardenings employed are of general type and the evolution of back stress follows the Armstrong-Frederick rule. Theoretical and numerical aspects are discussed in detail and a comparison is made with the classical backward Euler method  

    On the influence of centerline strain on the stability of a bimorph piezo-actuated microbeam

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1246-1252 ; 10263098 (ISSN) Abedinnasab, M. H ; Kamali Eigoli, A ; Zohoor, H ; Vossoughi, G ; Sharif University of Technology
    The nonlinear equation of motion for pre-stretched EulerBernoulli beams is derived. The effect of pre-tension and pre-compression in EulerBernoulli beams is studied. It is shown that compressive strain affects the bending stiffness much more than tensile strain. Based on the derived equation, the dynamic model of bimorph piezo-actuated beams, which is accurate, yet simple, is then developed. Afterwards, the critical voltage, which makes the piezo-actuated microbeam unstable, is numerically investigated. It is shown that the strain of the centerline is proportional to the beam's aspect ratio squared. Results show that the more the aspect ratio, the less the critical voltage. In addition, it... 

    Proposal of a new design for valveless micropumps

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1261-1266 ; 10263098 (ISSN) Afrasiab, H ; Movahhedy, M. R ; Assempour, A ; Sharif University of Technology
    A new design for a valveless micropumping device has been proposed that integrates two existing pumping technologies, namely, the wall induced traveling wave and the obstacle-type valveless micropump. The liquid in the microchannel is transported by generating a traveling wave on the channel, while the placing of two asymmetric trapezoid obstacles, along the centerline of the channel inlet and outlet, leads to a significant (up to seven times) increase of the net flow rate of the device. The effectiveness of this innovative design has been proved through a verified three-dimensional finite element model. FluidStructure Interaction (FSI) analysis is performed in the framework of an Arbitrary... 

    A comparative study of two cavitation modeling strategies for simulation of inviscid cavitating flows

    , Article Ocean Engineering ; Volume 108 , November , 2015 , Pages 257-275 ; 00298018 (ISSN) Hejranfar, K ; Ezzatneshan, E ; Fattah Hesari, K ; Sharif University of Technology
    Elsevier Ltd  2015
    In the present work, two cavitation modeling strategies, namely the barotropic cavitation model and the transport equation-based model are applied and assessed for the numerical simulation of inviscid cavitating flows over two-dimensional and axisymmetric geometries. The algorithm uses the preconditioned Euler equations employing the interface capturing method for both the cavitation models. A same numerical solution procedure is used herein for discretizing the governing equations resulting from these two cavitation modeling strategies for the assessment to be valid and reliable. A central difference finite-volume scheme employing the suitable dissipation terms to account for density jumps... 

    Buckling of variable section columns under axial loading

    , Article Journal of Engineering Mechanics ; Volume 136, Issue 4 , 2010 , Pages 472-476 ; 07339399 (ISSN) Darbandi, S. M ; Firouz Abadi, R. D ; Haddadpour, H ; Sharif University of Technology
    In this paper, the static stability of the variable cross section columns, subjected to distributed axial force, is considered. The presented solution is based on the singular perturbation method of Wentzel-Kramers-Brillouin and the column is modeled using Euler-Bernoulli beam theory. Closed-form solutions are obtained for calculation of buckling loads and the corresponding mode shapes. The obtained results are compared with the results in the literature to verify the present approach. Using numerous examples, it is shown that the represented solution has a very good convergence and accuracy for determination of the instability condition  

    Numerical simulation of shock-disturbances interaction in high-speed compressible inviscid flow over a blunt nose using weighted essentially non-oscillatory scheme

    , Article Wave Motion ; Volume 88 , 2019 , Pages 167-195 ; 01652125 (ISSN) Hejranfar, K ; Rahmani, S ; Sharif University of Technology
    Elsevier B.V  2019
    In the present study, shock-disturbances interaction in high-speed compressible inviscid flow is simulated utilizing the weighted essentially non-oscillatory (WENO) scheme by employing the shock-capturing technique. For this aim, the two-dimensional Euler equations in strong conservative form are discretized by using the explicit third-order TVD Runge–Kutta scheme in time and the fifth-order WENO finite difference scheme in space. The main advantage of using the WENO scheme is its capability for properly solving the discontinuities in the domain without needing any artificial viscosity, limiter function or filter. Hence, this scheme is stable, and thus, it is suitable for simulating very... 

    CFD modeling of gasification process in tapered fluidized bed gasifier

    , Article Energy ; Volume 191 , 2020 Askaripour, H ; Sharif University of Technology
    Elsevier Ltd  2020
    This article presents a two-dimensional simulation of the coal gasification in tapered fluidized bed gasifier. The effects of tapered angle, gasifier temperature, velocity of gasifying agent, and steam-to-air ratio on the gas compositions, lower heating value (LHV), and higher heating value (HHV) were examined. In order to find the appropriate operating conditions of coal gasification, carbon conversion efficiency (CCE) and cold gas efficiency (CGE) were also explored. It was found that with an increase of the gasifier temperature, CCE and CGE of the tapered gasifier diminishes. Increasing tapered angle results in a decrease of the LHV and HHV of the gas products, whereas the CCE of... 

    Large deformation finite element modeling of rubble mound breakwater built on soft seabed using coupled eulerian–lagrangian method

    , Article Indian Geotechnical Journal ; Volume 51, Issue 2 , 2021 , Pages 315-328 ; 09719555 (ISSN) Masoudi, S ; Shahir, H ; Pak, A ; Sharif University of Technology
    Springer  2021
    For the design of rubble mound breakwaters on soft soil, it is essential to predict the behavior of soft soil and large deformations phenomena occurring in the course of construction of the rubble mound breakwater. Large deformations in various problems can be well simulated using the coupled Eulerian–Lagrangian (CEL) method. In this study, the CEL method has been used to simulate the rubble mounds construction on soft soil and predict the resulting settlements. To validate the numerical model, the results of three experiments conducted in the physical modeling laboratory at Kharazmi University were used. Also, two case studies of real rubble mound breakwaters constructed on soft seabeds... 

    Comparison between Lagrangian and Eulerian approaches in predicting motion of micron-sized particles in laminar flows

    , Article Atmospheric Environment ; Vol. 89, issue , 2014 , Pages 199-206 ; ISSN: 13522310 Saidi, M. S ; Rismanian, M ; Monjezi, M ; Zendehbad, M ; Fatehiboroujeni, S ; Sharif University of Technology
    Modeling the behavior of suspended particles in gaseous phase is important for diverse reasons; e.g. aerosol is usually the main subject of CFD simulations in clean rooms. Additionally, to determine the rate and sites of deposition of particles suspended in inhaled air, the motion of the particles should be predicted in lung airways. Meanwhile there are two basically different approaches to simulate the behavior of particles suspension, Lagrangian and Eulerian approaches. This study compares the results of these two approaches on simulating the same problem. An in-house particle tracking code was developed to simulate the motion of particles with Lagrangian approach. In order to simulate the... 

    Modeling of moving boundaries in large plasticity deformations via an enriched arbitrary Lagrangian-Eulerian FE method

    , Article Scientia Iranica ; Volume 17, Issue 2 A , 2010 , Pages 141-160 ; 10263098 (ISSN) Anahid, M ; Khoei, A. R ; Sharif University of Technology
    In this paper, a new computational technique is presented for the modeling of moving boundaries in large plastic deformations based on an enriched arbitrary Lagrangian-Eulerian finite element method. An Arbitrary Lagrangian-Eulerian (ALE) technique is employed to capture the advantages of both Lagrangian and Eulerian methods and alleviate the drawbacks of mesh distortion in Lagrangian formulation. An enriched finite element method is implemented based on the extended FEM technique to capture the arbitrary interfaces independent of element boundaries. The process is accomplished by performing a splitting operator to separate the material (Lagrangian) phase from the convective (Eulerian)... 

    Modeling and simulation of barite deposition in an annulus space of a well using CFD

    , Article Journal of Petroleum Science and Engineering ; Volume 161 , 2018 , Pages 476-496 ; 09204105 (ISSN) Movahedi, H ; Shad, S ; Beagom Mokhtari Hosseini, Z ; Sharif University of Technology
    Elsevier B.V  2018
    In drilling industry, barite particles settling and barite sag as a major problem can potentially impose significant operational issues. Static conditions, in which well undergoes an extended shut-in period, could occur during different drilling and completion operations such fishing operation, tripping, and logging. Despite its importance, such phenomenon is not well understood yet. To avoid issues related to barite settlement and barite sag, a good understanding of the impact of different drilling parameters on barite settlement and sag phenomenon is required. Recently, the mathematical formulation and modeling of settlement and sag processes have gained more attention. In order to better...