Fluid Model simulations of 2D Alfven wave soliton structures in a 3D Electromagnetic plasma

2010 ◽  
Author(s):  
Satya Baboolal ◽  
Ramesh Bharuthram
Keyword(s):  
Fluid Model ◽  
Alfven Wave ◽  
Model Simulations

scholarly journals Reduced models accounting for parallel magnetic perturbations: gyrofluid and finite Larmor radius–Landau fluid approaches

2016 ◽  
Vol 82 (6) ◽  
Author(s):  
E. Tassi ◽  
P. L. Sulem ◽  
T. Passot
Keyword(s):  
Fluid Model ◽  
Collisionless Plasma ◽  
Low Frequency ◽  
Wave Model ◽  
Plasma Phys ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Closure Relation ◽  
Reduced Models ◽  
Finite Larmor Radius

Reduced models are derived for a strongly magnetized collisionless plasma at scales which are large relative to the electron thermal gyroradius and in two asymptotic regimes. One corresponds to cold ions and the other to far sub-ion scales. By including the electron pressure dynamics, these models improve the Hall reduced magnetohydrodynamics (MHD) and the kinetic Alfvén wave model of Boldyrev et al. (2013 Astrophys. J., vol. 777, 2013, p. 41), respectively. We show that the two models can be obtained either within the gyrofluid formalism of Brizard (Phys. Fluids, vol. 4, 1992, pp. 1213–1228) or as suitable weakly nonlinear limits of the finite Larmor radius (FLR)–Landau fluid model of Sulem and Passot (J. Plasma Phys., vol 81, 2015, 325810103) which extends anisotropic Hall MHD by retaining low-frequency kinetic effects. It is noticeable that, at the far sub-ion scales, the simplifications originating from the gyroaveraging operators in the gyrofluid formalism and leading to subdominant ion velocity and temperature fluctuations, correspond, at the level of the FLR–Landau fluid, to cancellation between hydrodynamic contributions and ion finite Larmor radius corrections. Energy conservation properties of the models are discussed and an explicit example of a closure relation leading to a model with a Hamiltonian structure is provided.

scholarly journals A two-fluid model describing the finite-collisionality, stationary Alfvén wave in anisotropic plasma

2008 ◽  
Vol 15 (6) ◽  
pp. 957-964 ◽  
Author(s):  
S. M. Finnegan ◽  
M. E. Koepke ◽  
D. J. Knudsen
Keyword(s):  
Fluid Model ◽  
Collisionless Plasma ◽  
Alfven Wave ◽  
Temperature Anisotropy ◽  
Thermal Pressure ◽  
Exclusion Region ◽  
Two Fluid Model ◽  
The Magnetic Field ◽  
Range Of Values ◽  
Two Fluid

Abstract. The stationary inertial Alfvén (StIA) wave (Knudsen, 1996) was predicted for cold, collisionless plasma. The model was generalized (Finnegan et al., 2008) to include nonzero values of electron and ion collisional resistivity and thermal pressure. Here, the two-fluid model is further generalized to include anisotropic thermal pressure. A bounded range of values of parallel electron drift velocity is found that excludes periodic stationary Alfvén wave solutions. This exclusion region depends on the value of the local Alfvén speed VA, plasma beta perpendicular to the magnetic field β⊥ and electron temperature anisotropy.

Two-Fluid Model Simulations of the National Energy Technology Laboratory Bubbling Fluidized Bed Challenge Problem

2016 ◽  
Vol 55 (17) ◽  
pp. 5063-5077 ◽  
Author(s):  
Musango Lungu ◽  
Haotong Wang ◽  
Jingdai Wang ◽  
Yongrong Yang ◽  
Fengqiu Chen
Keyword(s):  
Fluidized Bed ◽  
Fluid Model ◽  
Energy Technology ◽  
Model Simulations ◽  
Bubbling Fluidized Bed ◽  
Two Fluid Model ◽  
Two Fluid

Nonlinear decay of a propagating lower-hybrid wave in a plasma

1978 ◽  
Vol 19 (1) ◽  
pp. 87-96 ◽  
Author(s):  
P. K. Shukla ◽  
M. A. Mamedow
Keyword(s):  
Electromagnetic Waves ◽  
Fluid Model ◽  
Wave Interaction ◽  
Alfven Wave ◽  
Lower Hybrid ◽  
Threshold Condition ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Two Fluid Model ◽  
Two Fluid

This paper studies the nonlinear coupling between a large amplitude propagating lower-hybrid wave and two electromagnetic waves in a plasma. Using a two-fluid model and Vlasov and Maxwell's equations, we derive a dispersion relation governing this three-wave interaction process. It is shown that a finite wavenumber lower-hybrid pump can decay into a whistler and a kinetic Alfvén wave. Calculations of the threshold condition suggest that this decay process may occur both in the laboratory and in the ionosphere.

Numerical modeling of pedestal stability and broadband turbulence of wide-pedestal QH-mode plasmas on DIII-D

2022 ◽  
Author(s):  
Zeyu Li ◽  
Xi Chen ◽  
Christopher M Muscatello ◽  
Keith H Burrell ◽  
Xueqiao Xu ◽  
...  
Keyword(s):  
Fluid Model ◽  
Operation Mode ◽  
High Energy ◽  
Alfven Wave ◽  
Rotation Direction ◽  
Diamagnetic Drift ◽  
Spatial Locations ◽  
Trapped Electron ◽  
Possible Cause ◽  
Drift Direction

Abstract Wide pedestal Quiescent High confinement (QH) mode discovered on DIII-D in recent years is a stationary and quiescent H-mode with the pedestal width exceeding EPED prediction by at least 25%. Its characteristics, such as low rotation, high energy confinement and ELM-free operation, make it an attractive operation mode for future reactors. Linear and nonlinear simulations using BOUT++ reduced two fluid MHD model are carried out to investigate the bursty broadband turbulence often observed in the edge of wide-pedestal QH-mode plasmas. Two kinds of MHD-scale instabilities in different spatial locations within the pedestal were found in the simulations: one mild peeling-ballooning (PB) mode (γ_PB<0.04ω_A) located near the minimum in Er well propagating in ion diamagnetic drift direction; and one drift-Alfvén wave (DAW) locates at smaller radius compared to Er well propagating in the electron diamagnetic drift direction and unstable only when the parallel electron dynamics is included in the simulation. The coupling between drift wave and shear Alfvén wave provides a possible cause of the experimentally observed local profile flattening in the upper-pedestal. The rotation direction, mode location, as well as the wavenumber of these two modes from BOUT++ simulations agree reasonably well with the experimental measurements, while the lack of quantitatively agreement is likely due to the lack of trapped electron physics in current fluid model. This work presents improved physics understanding of the pedestal stability and turbulence dynamics for wide-pedestal QH-mode.

scholarly journals Use of α -shapes for the measurement of 3D bubbles in fluidized beds from two-fluid model simulations

2016 ◽  
Vol 288 ◽  
pp. 409-421 ◽  
Author(s):  
Ignacio Julián ◽  
David González ◽  
Javier Herguido ◽  
Miguel Menéndez
Keyword(s):  
Fluidized Beds ◽  
Fluid Model ◽  
Model Simulations ◽  
Two Fluid Model ◽  
Two Fluid

The Modeling of Lift and Dispersion Forces in Two-Fluid Model Simulations: Part I — Jet Flows

2003 ◽  
Author(s):  
M. Lopez de Bertodano ◽  
F. J. Moraga ◽  
D. A. Drew ◽  
R. T. Lahey
Keyword(s):  
Fluid Model ◽  
Phase 1 ◽  
Lift Coefficient ◽  
Turbulent Dispersion ◽  
Jet Flows ◽  
Dispersion Forces ◽  
Model Simulations ◽  
Turbulence Dispersion ◽  
Two Fluid Model ◽  
Two Fluid

Two-fluid model simulations of a bubbly vertical jet are presented. The purpose of these simulations is to assess the modeling of turbulence dispersion and lift forces in a free shear flow. Although turbulence dispersion forces have previously been validated using simpler canonical flows and microscopic particles or bubbles, there was a need to asses the model performance for larger bubbles in more turbulent flows. This method, of validating two-fluid models in flows of increasing complexity has the advantage of excluding, or at least minimizing, the possibility of cancellation of errors when modeling several forces. In a companion paper (see Part-II), the present two-fluid model is extended to a boundary layer in which forces induced by the presence of a wall are important. The turbulent dispersion models used herein are based on the application of a kinetic transport equation, similar to Boltzmann’s equation, to obtain the turbulent diffusion force for the dispersed phase [1, 2]. They have already been constituted and validated for the case of particles in homogeneous turbulence and jets [3] and for microscopic bubbles in grid generated turbulence and mixing layers [4]. It was found that it is possible to simulate the experimental data in Ref. [5] (See Figures-1 to 4) for a bubbly jet with 1 mm diameter bubbles. Good agreement is obtained using the model of Brucato et al. [7] for the modulation of the drag force by the liquid phase turbulence and a constant lift coefficient, CL. However, little sensitivity is observed to the value of the lift coefficient in the range 0 &lt; CL &lt; 0.29.

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