Discussion on Clustering Effects in Vertical Gas-Particle Flows

2000 ◽  
Author(s):  
Eivind Helland ◽  
Rene Occelli ◽  
Lounes Tadrist
Keyword(s):  
Gas Phase ◽  
Stokes Equations ◽  
Lagrangian Approach ◽  
Inelastic Collisions ◽  
Navier Stokes ◽  
Coupling Term ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Drag Forces ◽  
Particle Flows

Abstract Simulations of 2D gas-particle flows in a vertical riser using a mixed Eulerian-Lagrangian approach are addressed. The model for the interstitial gas phase is based on the Navier-Stokes equations for two-phase flow with a coupling term between the gas and solid phases due to drag forces. The motion of particles is treated by a Lagrangian approach and the particles are assumed to interact through binary, instantaneous, non-frontal, inelastic collisions with friction. In this paper different particle clustering effects in the gas-particle flow is investigated.

A Numerical Solution for Gas-Particle Flows at High Reynolds Numbers

1981 ◽  
Vol 48 (3) ◽  
pp. 465-471 ◽  
Author(s):  
J. A. Laitone
Keyword(s):  
Numerical Solution ◽  
Coal Gasification ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Particle Flows ◽  
Energy Conversion Systems ◽  
Successful Design ◽  
High Reynolds

Predicting the fluid mechanical characteristics of a gas-solid two-phase flow is critical for the successful design and operation of coal gasification systems, coal fired turbines, rocket nozzles, and other energy conversion systems. This work presents a general grid-free numerical solution which extends a numerical solution of the Navier-Stokes equations developed by Chorin to a solution suitable for unsteady or steady dilute gas-solid particle flows. The method is applicable to open or closed domains of arbitrary geometry. The capability of the method is illustrated by analyzing the flow of gas and particles about a cylinder. Good agreement is found between the numerical method and experiment.

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

NUMERICAL SIMULATION OF ISOTHERMAL AND THERMAL TWO-PHASE FLOWS USING PHASE-FIELD MODELING

2007 ◽  
Vol 18 (04) ◽  
pp. 536-545 ◽  
Author(s):  
NAOKI TAKADA ◽  
AKIO TOMIYAMA
Keyword(s):  
Phase Field ◽  
Stokes Equations ◽  
Density Ratio ◽  
Navier Stokes ◽  
Phase Field Modeling ◽  
Two Phase Flows ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Field Modeling ◽  
High Density Ratio

For interface-tracking simulation of two-phase flows in various micro-fluidics devices, we examined the applicability of two versions of computational fluid dynamics method, NS-PFM, combining Navier-Stokes equations with phase-field modeling for interface based on the van der Waals-Cahn-Hilliard free-energy theory. Through the numerical simulations, the following major findings were obtained: (1) The first version of NS-PFM gives good predictions of interfacial shapes and motions in an incompressible, isothermal two-phase fluid with high density ratio on solid surface with heterogeneous wettability. (2) The second version successfully captures liquid-vapor motions with heat and mass transfer across interfaces in phase change of a non-ideal fluid around the critical point.

scholarly journals Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3092
Author(s):  
Lourenço Sassetti Mendes ◽  
Javier L. Lara ◽  
Maria Teresa Viseu
Keyword(s):  
Stokes Equations ◽  
Cost Benefit ◽  
Volume Of Fluid ◽  
Navier Stokes ◽  
Type Model ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Entrained Air ◽  
Computational Resources ◽  
Mesh Convergence

Spillway design is key to the effective and safe operation of dams. Typically, the flow is characterized by high velocity, high levels of turbulence, and aeration. In the last two decades, advances in computational fluid dynamics (CFD) made available several numerical tools to aid hydraulic structures engineers. The most frequent approach is to solve the Reynolds-averaged Navier–Stokes equations using an Euler type model combined with the volume-of-fluid (VoF) method. Regardless of a few applications, the complete two-phase Euler is still considered to demand exorbitant computational resources. An assessment is performed in a spillway offset aerator, comparing the two-phase volume-of-fluid (TPVoF) with the complete two-phase Euler (CTPE). Both models are included in the OpenFOAM® toolbox. As expected, the TPVoF results depend highly on the mesh, not showing convergence in the maximum chute bottom pressure and the lower-nappe aeration, tending to null aeration as resolution increases. The CTPE combined with the k–ω SST Sato turbulence model exhibits the most accurate results and mesh convergence in the lower-nappe aeration. Surprisingly, intermediate mesh resolutions are sufficient to surpass the TPVoF performance with reasonable calculation efforts. Moreover, compressibility, flow bulking, and several entrained air effects in the flow are comprehended. Despite not reproducing all aspects of the flow with acceptable accuracy, the complete two-phase Euler demonstrated an efficient cost-benefit performance and high value in spillway aerated flows. Nonetheless, further developments are expected to enhance the efficiency and stability of this model.

Modeling of Cell Motion in Micro-Scale Hydrodynamic-Electrical Field

2009 ◽  
Vol 74 ◽  
pp. 139-142
Author(s):  
Ting Ye ◽  
Hua Li
Keyword(s):  
Stokes Equations ◽  
Elastic Shell ◽  
Practical Significance ◽  
Cell Manipulation ◽  
Navier Stokes ◽  
Phase System ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Maxwell Stress Tensor ◽  
Cell Motion

A modeling of two-phase system is presented for investigation of the cell motion and deformation in the microchannel subject to the mechanical and electrical coupled forces. In order to evaluate the mechanical force developed by cell membrane, it is treated as an incompressible and elastic shell with uniform thickness capable of shearing and bending deformation. Due to the irregular and complex cell configuration after deformation, the Maxwell stress tensor (MST) method is successfully employed to analyze the dielectrophoretic force. The modified particle binary level set (MPBLS) method is presented to accurately track the moving interface between the two phases, which is vital for a modeling of two-phase system. Afterwards the modified SIMPLER coupled with SIMPLEC is used to numerically solve the incompressible Navier-Stokes equations governing the entire flow field. On basis of the series of methods, the motion and deformation of red blood cell (RBC) in the microchannel under the mechanical and electrical forces are simulated to demonstrate the deformation process and the moving trajectory of RBC. The present study is not only of great value for deeper understanding of some diseases caused by cell abnormality, but also of practical significance for cell manipulation and separation.

scholarly journals Aerodynamic Sensitivity Analysis for a Wind Turbine Airfoil in an Air-Particle Two-Phase Flow

2019 ◽  
Vol 9 (18) ◽  
pp. 3909 ◽  
Author(s):  
Tongqing Guo ◽  
Junjun Jin ◽  
Zhiliang Lu ◽  
Di Zhou ◽  
Tongguang Wang
Keyword(s):  
Wind Turbine ◽  
Stokes Equations ◽  
Angle Of Attack ◽  
Performance Degradation ◽  
Navier Stokes ◽  
Discrete Phase Model ◽  
Two Phase ◽  
Naca0012 Airfoil ◽  
Particle Flows ◽  
Wind Turbine Airfoil

In this paper, the Navier-Stokes equations coupled with a Lagrangian discrete phase model are described to simulate the air-particle flows over the S809 airfoil of the Phase VI blade, the NH6MW25 airfoil of a 6 MW wind turbine blade and the NACA0012 airfoil. The simulation results demonstrate that, in an attached flow, the slight performance degradation is caused by the boundary layer momentum loss. After flow separation, the performance degradation becomes significant and is dominated by a more extensive separation due to particles, since the aerodynamic coefficient increments and the moving distance of separation point present similar variation trends with increasing angle of attack. Unlike the NACA0012 airfoil, a most particle-sensitive angle of attack is found in the light stall region for a wind turbine airfoil, at which the lift decrement and the drag increment reach their peak values. For the S809 airfoil, the most sensitive angle of attack is about 3° higher than that for the maximum lift-to-drag ratio. Hence, the aerodynamic performance of a wind turbine is very susceptible to particles. Based on the most sensitive angles of attack, the more sensitive scope of angles of attack of a blade airfoil and the more sensitive range of rotor tip speed ratios are predicted sequentially. The present study clarifies the principles for the performance degradation of a wind turbine airfoil due to particles and the conclusions are useful for the wind turbine design reducing the particle influences.

scholarly journals Simulating two-phase flows with thermodynamically consistent energy stable Cahn-Hilliard Navier-Stokes equations on parallel adaptive octree based meshes

2020 ◽  
Vol 419 ◽  
pp. 109674
Author(s):  
Makrand A. Khanwale ◽  
Alec D. Lofquist ◽  
Hari Sundar ◽  
James A. Rossmanith ◽  
Baskar Ganapathysubramanian
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Two Phase Flows ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Energy Stable

scholarly journals CLSVOF Method to Study the Formation Process of Taylor Cone in Crater-Like Electrospinning of Nanofibers

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Yong Liu ◽  
Jia Li ◽  
Yu Tian ◽  
Xia Yu ◽  
Jian Liu ◽  
...  
Keyword(s):  
Viscous Liquid ◽  
Formation Process ◽  
Stokes Equations ◽  
Taylor Cone ◽  
Computational Method ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Cone Formation ◽  
Computational Fluid Dynamics Cfd

The application of two-phase computational fluid dynamics (CFD) for simulating crater-like Taylor cone formation dynamics in a viscous liquid is a challenging task. An interface coupled level set/volume-of-fluid (CLSVOF) method and the governing equations based on Navier-Stokes equations were employed to simulate the crater-like Taylor cone formation process. The computational results of the dynamics of crater-like Taylor cone slowly formed on a free liquid surface produced by a submerged nozzle in a viscous liquid were presented in this paper. Some experiments with different air pressures were carried out to evaluate the simulation results. The results from both CFD and experimental observations were compared and analyzed. The numerical results were consistent with the experimental results. Our study showed that the CLSVOF method gave convincing results, and the computational method is robust to extreme variations in interfacial topology.

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