A Numerical Study of the Influence of Particle Density on Lift Force-Induced Separation in a Micro-Separator/Classifier by a Macroscopic Particle Model

2007 ◽  
Vol 40 (11) ◽  
pp. 986-992 ◽  
Author(s):  
Shinichi Ookawara ◽  
Madhusuden Agrawal ◽  
David Street ◽  
Kohei Ogawa
Keyword(s):  
Lift Force ◽  
Particle Density ◽  
Numerical Study ◽  
Particle Model

A Numerical Study of Quantum Decoherence

2012 ◽  
Vol 12 (1) ◽  
pp. 85-108 ◽  
Author(s):  
Riccardo Adami ◽  
Claudia Negulescu
Keyword(s):  
Density Matrix ◽  
Particle Density ◽  
Numerical Study ◽  
Heavy Particle ◽  
Splitting Method ◽  
Time Dependent ◽  
Quantum Decoherence ◽  
Approximation Formula ◽  
Time Splitting ◽  
Decoherence Effect

AbstractThe present paper provides a numerical investigation of the decoherence effect induced on a quantum heavy particle by the scattering with a light one. The time dependent two-particle Schrödinger equation is solved by means of a time-splitting method. The damping undergone by the non-diagonal terms of the heavy particle density matrix is estimated numerically as well as the error in the Joos-Zeh approximation formula.

Numerical Study on Vortex-Induced Motions of Semisubmersibles With Three Columns With Different Sections Types

2019 ◽  
Author(s):  
Chenling Tian ◽  
Longfei Xiao ◽  
Mingyue Liu ◽  
Lijun Yang ◽  
Jing Liu
Keyword(s):  
Wind Turbine ◽  
Lift Force ◽  
Transverse Direction ◽  
Numerical Study ◽  
Offshore Structures ◽  
Detached Eddy Simulation ◽  
Fluid Forces ◽  
Eddy Simulation ◽  
Resonance Behavior ◽  
Induced Motion

Abstract Vortex-induced motion (VIM) phenomenon is a great challenge for design and operation of offshore structures subjected to ocean flow. Semi-submersibles with three columns are often applied to the field of wind turbine, suffering VIM motions probably. In recent years, it is showed that many factors have more or less influence on VIM of platforms. A comparison of circular columns with square columns on VIM characteristics of three-column semisubmersibles is carried out using the detached eddy simulation (DES) method via Star-ccm+ software. This paper analyzes motions in the transverse direction and yaw, as well as fluid forces including drag force and fluctuating lift force. The results show that transverse amplitudes of semisubmersible with three square columns are much lower than those of semisubmersible with three circular columns at all incidences. Besides, the authors conclude that the semisubmersible with three square columns do not experience obvious resonance behavior, which is different from the semisubmersible with three circular columns. Besides, galloping phenomenon occurred at large reduced velocities at 0°-incidence for the semisubmersible with three square columns, which is likely not induced by lift force directly. Meanwhile, in these cases, yaw amplitudes are also larger than the others. This may be due to the galloping behavior, which is just a conjecture.

Numerical study on the shear-induced lift force acting on a spherical bubble in aqueous surfactant solutions

2008 ◽  
Vol 20 (4) ◽  
pp. 040704 ◽  
Author(s):  
Masato Fukuta ◽  
Shu Takagi ◽  
Yoichiro Matsumoto
Keyword(s):  
Lift Force ◽  
Numerical Study ◽  
Spherical Bubble ◽  
Surfactant Solutions

Scouring Below Pipelines: The Role of Vorticity and Turbulence

2010 ◽  
Author(s):  
Matteo Mattioli ◽  
Alessandro Mancinelli ◽  
Giuseppina Colicchio ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Lift Force ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Offshore Pipeline ◽  
Temporal Averaging ◽  
Force Components

A numerical study on the turbulence and vorticity of local scour underneath an offshore pipeline placed on a non-cohesive sandy seabed and forced by a steady flow current is presented. The numerical model solves the Navier-Stokes equations using an innovative Level Set technique. The model predicts the behavior of the movable sediments through both drift and lift force components. Mean and turbulent flow quantities were extracted by temporal averaging. Results on the distribution and evolution of turbulent kinetic energy and vorticity will be illustrated at the conference.

scholarly journals Numerical Analysis of Lift Generation in a Radial Segmented Gas Seal

2019 ◽  
Author(s):  
Mihai Arghir ◽  
Samia Dahite
Keyword(s):  
Numerical Analysis ◽  
Lift Force ◽  
Previous Analysis ◽  
Numerical Study ◽  
Rotor Speed ◽  
Rotating Shaft ◽  
Annular Ring ◽  
Thrust Bearings ◽  
Unsteady Problem ◽  
Face Seals

Abstract A radial segmented seal is composed of three or six carbon segments that are assembled by a circumferential (garter) spring that presses them against the rotor. Assembled, they take the form of an annular ring. Each segment has several pads that generate a radial lift force depending on the rotor speed. There are many ways of creating effective lift forces. For example, a pocket on the pad creates a lift force because each pad will act as a Rayleigh step bearing. A groove on the rotating shaft will also create a radial lift force on the pad. However, this latter lift force will be unsteady. The aim of the present work is the numerical study of the lift created by a grooved rotor on a pad. Due to the very small operating radial clearances of radial segmented seals (less than 10 μm), the problem can be simplified by analyzing a single pad and a grooved runner. Previous analysis of gas face seals or thrust bearings always considered grooved pads and a smooth runner, even when the runner was grooved. The peculiarity of this study, which is the first of its kind, is considering the unsteady problem of the moving runner grooves. The analysis was performed for a single pad of a radial segmented seal operating with air.

A Numerical Study on Erosion Model Selection and Effect of Pump Type and Sand Characters in Electrical Submersible Pumps by Sandy Flow

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Haiwen Zhu ◽  
Jianjun Zhu ◽  
Risa Rutter ◽  
Hong-Quan Zhang
Keyword(s):  
Particle Density ◽  
Numerical Study ◽  
Petroleum Industry ◽  
Affecting Factors ◽  
Discrete Phase Model ◽  
Erosion Model ◽  
Erosion Rates ◽  
Artificial Lift ◽  
Erosion Models ◽  
Electrical Submersible Pumps

AbstractThe electrical submersible pump (ESP) is one of the most widely used artificial lift methods in the petroleum industry. Although not recommended to be used in sand production well, ESP is still applicable in high producing well with a minimal percentage of solid concentration. Besides, the temporarily produced fracture sand from the proppant backflow can also severely reduce ESP boosting ability in weeks or months. Therefore, it is crucial to study the wear in ESP stages under sandy flow condition. Various erosion equations and models were developed for different materials and affecting factors. However, the predictions of these erosion models in ESPs need to be evaluated to make a proper selection. Comparisons of wear patterns and erosion rates were conducted using the computational fluid dynamics (CFD) software ANSYS. In order to validate the simulation results, an experimental facility was designed and constructed to study the sand erosion process in an ESP. Stages were painted to obtain erosion patterns, and the weight loss was measured. Six erosion models were implemented in the simulations to select the most accurate one in predicting ESP erosion rates. Then, three ESPs, including two mixed-type pumps and one radial-type pump, were modeled to study the effect of pump types with the selected erosion model. Finally, the steady-state discrete phase model (DPM) erosion simulations were carried out to investigate particle density and size effects.

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