1,054 research outputs found
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Mini-Workshop: Innovative Trends in the Numerical Analysis and Simulation of Kinetic Equations
In multiscale modeling hierarchy, kinetic theory plays a vital role in connecting microscopic Newtonian mechanics and macroscopic continuum mechanics. As computing power grows, numerical simulation of kinetic equations has become possible and undergone rapid development over the past decade. Yet the unique challenges arising in these equations, such as highdimensionality, multiple scales, random inputs, positivity, entropy dissipation, etc., call for new advances of numerical methods. This mini-workshop brought together both senior and junior researchers working on various fastpaced growing numerical aspects of kinetic equations. The topics include, but were not limited to, uncertainty quantification, structure-preserving methods, phase transitions, asymptotic-preserving schemes, and fast methods for kinetic equations
Nonlinear gyrokinetic PIC simulations in stellarators with the code EUTERPE
In this work, the first nonlinear particle-in-cell simulations carried out in
a stellarator with the global gyrokinetic code EUTERPE using realistic plasma
parameters are reported. Several studies are conducted with the aim of enabling
reliable nonlinear simulations in stellarators with this code. First, EUTERPE
is benchmarked against ORB5 in both linear and nonlinear settings in a tokamak
configuration. Next, the use of noise control and stabilization tools, a
Krook-type collision operator, markers weight smoothing and heating sources is
investigated. It is studied in detail how these tools influence the linear
growth rate of instabilities in both tokamak and stellarator geometries and
their influence on the linear zonal flow evolution in a stellarator. Then, it
is studied how these tools allow improving the quality of the results in a set
of nonlinear simulations of electrostatic turbulence in a stellarator
configuration.
Finally, these tools are applied to a W7-X magnetic configuration using
experimental plasma parameters.Comment: 24 pages, 19 figure
On the definition of a kinetic equilibrium in global gyrokinetic simulations
Nonlinear electrostatic global gyrokinetic simulations of collisionless ion temperature gradient (ITG) turbulence and ExB zonal flows in axisymmetric toroidal plasmas are examined for different choices of the initial distribution function. Using a local Maxwellian leads to the generation of axisymmetric ExB flows that can be so strong as to prevent ITG mode growth. A method using a canonical Maxwellian is shown to avoid this spurious generation of ExB flows. In addition, a revised delta f scheme is introduced and compared to the standard delta f method. (c) 2006 American Institute of Physics
Simulations of an ASA flow crystallizer with a coupled stochastic-deterministic approach
A coupled solver for population balance systems is presented, where the flow, temperature, and concentration equations are solved with finite element methods, and the particle size distribution is simulated with a stochastic simulation algorithm, a so-called kinetic Monte-Carlo method. This novel approach is applied for the simulation of an axisymmetric model of a tubular flow crystallizer. The numerical results are compared with experimental data
Recommended from our members
Simulations of an ASA flow crystallizer with a coupled stochastic-deterministic approach
A coupled solver for population balance systems is presented, where the
flow, temperature, and concentration equations are solved with finite element
methods, and the particle size distribution is simulated with a stochastic
simulation algorithm, a so-called kinetic Monte-Carlo method. This novel
approach is applied for the simulation of an axisymmetric model of a tubular
flow crystallizer. The numerical results are compared with experimental data
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