Numerical and Experimental Studies of Liquid Sloshing in Rectangular Tanks Using a Particle Method

2008 ◽  
Author(s):  
M. M. Gao ◽  
C. G. Koh ◽  
C. Luo
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Particle Method ◽  
Wave Theory ◽  
Particle Number Density ◽  
Numerical Results ◽  
Published Data ◽  
Navier Stokes Equation ◽  
Shake Table Tests ◽  
Inclined Angle

The sloshing waves in rectangular tanks are studied experimentally and numerically based on the fully nonlinear wave theory. A moving-particle semi-implicit (MPS) method belonging to the category of the particle method is utilized to solve the Navier-Stokes equation that is the governing equation of the incompressible fluids. The motion of each particle is calculated through interactions with neighboring particles covered with the kernel function. The governing equations are solved by Lagrangian approach and no grid is needed in the computation. The incompressibility is satisfied by keeping the particle number density constant. When the tank undergoes two-dimensional motion, the numerical results obtained are found to be in good agreement with other published data as well as our experimental results obtained by shake-table tests. Experiments with rectangular tanks have been conducted to validate the numerical results, for which favorable agreement is shown. Results will also be presented for the study which is currently extended to three dimensional sloshing by exciting the tank at an inclined angle.

scholarly journals Three Dimensional Vibration Analysis of a Class of Traction-Free Solid Elastic Bodies with an Eccentric Cavity

2012 ◽  
Vol 19 (6) ◽  
pp. 1341-1357 ◽  
Author(s):  
Seyyed M. Hasheminejad ◽  
Yaser Mirzaei
Keyword(s):  
Vibration Analysis ◽  
Three Dimensional ◽  
Free Vibration Analysis ◽  
Numerical Results ◽  
Mode Shapes ◽  
Computational Techniques ◽  
Published Data ◽  
Elastic Structures ◽  
Wide Range ◽  
Vibrational Characteristics

A three-dimensional elasticity-based continuum model is developed for describing the free vibrational characteristics of an important class of isotropic, homogeneous, and completely free structural bodies (i.e., finite cylinders, solid spheres, and rectangular parallelepipeds) containing an arbitrarily located simple inhomogeneity in form of a spherical or cylindrical defect. The solution method uses Ritz minimization procedure with triplicate series of orthogonal Chebyshev polynomials as the trial functions to approximate the displacement components in the associated elastic domains, and eventually arrive at the governing eigenvalue equations. An extensive review of the literature spanning over the past three decades is also given herein regarding the free vibration analysis of elastic structures using Ritz approach. Accuracy of the implemented approach is established through proper convergence studies, while the validity of results is demonstrated with the aid of a commercial FEM software, and whenever possible, by comparison with other published data. Numerical results are provided and discussed for the first few clusters of eigen-frequencies corresponding to various mode categories in a wide range of cavity eccentricities. Also, the corresponding 3D mode shapes are graphically illustrated for selected eccentricities. The numerical results disclose the vital influence of inner cavity eccentricity on the vibrational characteristics of the voided elastic structures. In particular, the activation of degenerate frequency splitting and incidence of internal/external mode crossings are confirmed and discussed. Most of the results reported herein are believed to be new to the existing literature and may serve as benchmark data for future developments in computational techniques.

Transport phenomena and evolution mechanism of the melt pool during a laser based metal melting process

2021 ◽  
pp. 1-36
Author(s):  
Qingfei Bian ◽  
Ke Tian ◽  
Kong Ling ◽  
Yitung Chen ◽  
Min Zeng ◽  
...  
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Melting Process ◽  
Numerical Results ◽  
Interface Morphology ◽  
Momentum Exchange ◽  
Interface Capturing ◽  
Melt Pool ◽  
Metal Melting

Abstract This article presents a fully three-dimensional numerical study on the process of melt pool evolution. In order to overcome the simplifications used in many existing studies, an enthalpy method is developed for the phase change, and an accurate interface capturing method, i.e., the coupled volume-of-fluid and level set (VOSET) method, is employed to track the moving gas-liquid interface. Meanwhile, corresponding experimental studies are carried out for the purpose of validation. The obtained numerical results show the formed interface morphology during the process of melt pool with its typical sizes and are quantitatively consistent with those data measured in experiments. Based on the numerical results, the thermodynamic phenomena, induced by the interaction between heat and momentum exchange, occurring in the formation of melt pool are presented and discussed. Mechanisms of the melt pool evolution revealed in the present study provide a useful guidance for better controlling the process of additive manufacturing.

Unsteady Numerical Analysis of Flow Across 2D Cylinder

2010 ◽  
Author(s):  
Yaling Peng ◽  
Zhiguo Zhang ◽  
Fangliang Wu ◽  
Dakui Feng
Keyword(s):  
Strouhal Number ◽  
Excellent Agreement ◽  
Incidence Angle ◽  
Flow Direction ◽  
Incident Angle ◽  
Numerical Results ◽  
Published Data ◽  
Angle Of Incidence ◽  
Square Cylinder ◽  
Navier Stokes Equation

2-D computational analyses were conducted for unsteady viscous flow across cylinders of different geometries and different incident angle. Circular, square and elliptic (both at 0° and 90° angles of incidence) cylinders were examined. The calculations were performed by solving the unsteady 2-D Navier-Stokes equation at Re = 100. The calculated results produce drag and lift coefficients, as well as Strouhal number in excellent agreement with published data. Calculations for unsteady, incompressible 2D flow around a square cylinder at incidence angle of 0° and 45° and for Reynolds number = 100 were carried out. Cycle independence and grid independence results were obtained for the Strouhal number. The results were in excellent agreement with the available experimental and numerical results. Numerical results show that the Strouhal number increases with fluid angle of incidence on the cylinder. The wake behind the cylinder is wider and more violent for a square cylinder at 45° incidence compared to a square at 0° this is due to the increase in the characteristic length in the flow direction. The Strouhal number is highest for elliptic geometry among all cylinders in this research. For the geometries elliptic at 0° at Re = 100, there is not vortex shedding behind the cylinder. This is due to dominance of inertia forces over viscous forces. The present study was carried out for a 2-D single cylinder at fixed location inside a channel for unidirectional velocity. To get more accurate results computation on 3-D geometry should be carried out.

Mathematical modeling of electron irradiation of oil

2018 ◽  
Vol 35 (5) ◽  
pp. 1998-2009
Author(s):  
Assylzhan Kizbayev ◽  
Dauren Zhakebayev ◽  
Ualikhan Abdibekov ◽  
Askar Khikmetov
Keyword(s):  
Mathematical Model ◽  
Electron Irradiation ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Hydrocarbon Mixture ◽  
Navier Stokes Equation ◽  
Content Type ◽  
The Matrix ◽  
Crank Nicolson

Purpose This paper aims to propose a mathematical model and numerical modeling to study the behavior of low conductive incompressible multicomponent hydrocarbon mixture in a channel under the influence of electron irradiation. In addition, it also aims to present additional mechanisms to study the radiation transfer and the separation of the mixture’s components. Design/methodology/approach The three-dimensional non-stationary Navier–Stokes equation is the basis for this model. The Adams–Bashforth scheme is used to solve the convective terms of the equation of motion using a fourth-order accuracy five-point elimination method, and the viscous terms are computed with the Crank–Nicolson method. The Poisson equation is solved with the matrix sweep method and the concentration and electron irradiation equations are solved with the Crank–Nicolson method too. Findings It shows high computational efficiency and good estimation quality. On the basis of numerical results of mathematical model, the effect of the separation of mixture to fractions with various physical characteristics was obtained. The obtained results contribute to the improvement of technologies for obtaining high-quality oil products through oil separation into light and heavy fractions. Mathematical model is approbated based on test problem, and has good agreement with the experimental data. Originality/value The constructed mathematical model makes developing a methodology for conducting experimental studies of this phenomenon possible.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Thoracoabdominalis aortakirekesztés során fellépő elektrofiziológiai változások a gerincvelőben

2020 ◽  
Vol 73 (4) ◽  
pp. 160-166
Author(s):  
Csaba Dzsinich ◽  
Péter Gloviczki ◽  
Gabriella Nagy ◽  
Klaudia Vivien Nagy
Keyword(s):  
Spinal Cord ◽  
Motor Evoked Potentials ◽  
Spinal Cord Ischemia ◽  
Experimental Studies ◽  
Neuron Specific Enolase ◽  
Neurological Complications ◽  
Neurologic Outcome ◽  
Published Data ◽  
Aortic Clamping ◽  
Sensory Evoked

Összefoglaló. A thoracoabdominalis aortakirekesztés okozta gerincvelő ischemia súlyos neurológiai következményeit számos klinikai és kísérleti tanulmány bizonyítja. E nehezen kiszámítható, súlyos szövődmény megelőzésének érdekében régi törekvés megfelelő intra- és posztoperatív monitorizálás kifejlesztése, ami előre jelzi a gerincvelő-funkció romlását, illetve a kialakuló celluláris károsodást. A legelterjedtebb, a klinikai gyakorlatban széles körben alkalmazott megoldás a gerincvelői kiváltott motoros potenciál (MEP) folyamatos ellenőrzése. Ritkábban alkalmazott – bár ígéretes – eljárás a biokémiai változások nyomon követése, ami a sejtszintű károsodás markereit használja fel az ischemia okozta változások felismerésére. Korábbi dolgozatunkban kutyákon végzett kísérleteink azon eredményeit ismertettük, amelyekben a 60 perces thoracoabdominalis aortakirekesztés okozta neurológiai változások és a perfúzió adatainak összefüggéseit tárgyaltuk. Jelen tanulmányunkban a gerincvelői motoros (MEP) és szenzoros (SEP) kiváltott potenciálok változásait vizsgáljuk a neurológiai végállapot vonatkozásában. Megállapítottuk, hogy SEP változásai a neurológiai károsodás mértékével értékelhető összefüggést nem mutatnak. A MEP-amplitúdó és -latencia értékei biztonsággal jelzik a fenyegető gerincvelő ischemiát. A neurológiai deficit mélységét (Tarlov 2,1,0) a MEP-értékek változásai numerikusan nem értékelhetően követik. Summary. Severe neurological complications of the thoracoabdominal aortic clamping were published in numerous clinical and experimental studies. These hardly predictable, devastating consequences demanded to develop a monitoring system which might detect impending level of spinal cord ischemia in time – in order to introduce or enhance protective procedures and prevent permanent neurological deficit. The most widely used monitoring in clinical practice is the continuous surveillance of the motor evoked potentials (MEP) during and after thoracoabdominal aortic clamping. Much less used, but promising opportunity is to control the metabolic changes and cellular integrity utilizing specific markers like liquor lactate and neuron specific enolase (NSE) etc. In our earlier study we published data of our canine experiment related to coherencies between neurological outcome and specific perfusion of the spinal cord during and after one hour thoracoabdominal aortic clamping. In the present paper we investigate the behavior of motor evoked (MEP) and sensory evoked (SEP) potentials related to neurological changes. We conclude the behavior of SEP values hardly correlate with the neurologic outcome, meanwhile decrease of MEP amplitude provides reliable signal for developing spinal cord ischemia. We could not confirm a numeric correlation of these data and the level of the final neurologic outcome.

scholarly journals A Fast Two-Dimensional Numerical Method for the Wake Simulation of a Vertical Axis Wind Turbine

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 49
Author(s):  
Zheng Yuan ◽  
Jin Jiang ◽  
Jun Zang ◽  
Qihu Sheng ◽  
Ke Sun ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Numerical Method ◽  
Three Dimensional ◽  
Particle Method ◽  
Vortex Method ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Wake Effect ◽  
Array Design

In the array design of the vertical axis wind turbines (VAWT), the wake effect of the upstream VAWT on the downstream VAWT needs to be considered. In order to simulate the velocity distribution of a VAWT wake rapidly, a new two-dimensional numerical method is proposed, which can make the array design easier and faster. In this new approach, the finite vortex method and vortex particle method are combined to simulate the generation and evolution of the vortex, respectively, the fast multipole method (FMM) is used to accelerate the calculation. Based on a characteristic of the VAWT wake, that is, the velocity distribution can be fitted into a power-law function, a new correction model is introduced to correct the three-dimensional effect of the VAWT wake. Finally, the simulation results can be approximated to the published experimental results in the first-order. As a new numerical method to simulate the complex VAWT wake, this paper proves the feasibility of the method and makes a preliminary validation. This method is not used to simulate the complex three-dimensional turbulent evolution but to simulate the velocity distribution quickly and relatively accurately, which meets the requirement for rapid simulation in the preliminary array design.

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