scholarly journals Conservation laws for collisional and turbulent transport processes in toroidal plasmas with large mean flows

2017 ◽  
Vol 24 (2) ◽  
pp. 020701 ◽  
Author(s):  
H. Sugama ◽  
M. Nunami ◽  
M. Nakata ◽  
T.-H. Watanabe
Keyword(s):  
Conservation Laws ◽  
Turbulent Transport ◽  
Transport Processes ◽  
Toroidal Plasmas

scholarly journals Analytic slowing-down distributions as modified by turbulent transport

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
G. J. Wilkie
Keyword(s):  
Particle Density ◽  
Plasma Heating ◽  
Turbulent Transport ◽  
A Priori ◽  
High Energy ◽  
Relative Strength ◽  
Distribution Functions ◽  
Toroidal Plasmas ◽  
Model Distribution ◽  
Phase Space Transport

The effect of electrostatic microturbulence on fast particles rapidly decreases at high energy, but can be significant at moderate energy. Previous studies found that, in addition to changes in the energetic particle density, this results in non-trivial changes to the equilibrium velocity distribution. These effects have implications for plasma heating and the stability of Alfvén eigenmodes, but make multiscale simulations much more difficult without further approximations. Here, several related analytic model distribution functions are derived from first principles. A single dimensionless parameter characterizes the relative strength of turbulence relative to collisions, and this parameter appears as an exponent in the model distribution functions. Even the most simple of these models reproduces key features of the numerical phase-space transport solution and provides a useful a priori heuristic for determining how strong the effect of turbulence is on the redistribution of energetic particles in toroidal plasmas.

New possibilities for the mathematical modelling of turbulent transport processes in plasma

2012 ◽  
Author(s):  
Ν. N. Skvortsova ◽  
G. M. Batanov ◽  
A. E. Petrov ◽  
A. A. Pshenichnikov ◽  
K. A. Sarksyan ◽  
...  
Keyword(s):  
Mathematical Modelling ◽  
Turbulent Transport ◽  
Transport Processes

On the analysis of turbulent transport processes in nonreacting multijet burner flows

1992 ◽  
Vol 13 (2-3) ◽  
pp. 179-189 ◽  
Author(s):  
M. V. Heitor ◽  
A. L. N. Moreira
Keyword(s):  
Turbulent Transport ◽  
Transport Processes

New approach to the probabilistic-statistical analysis of turbulent transport processes in plasma

2002 ◽  
Vol 28 (2) ◽  
pp. 111-124 ◽  
Author(s):  
G. M. Batanov ◽  
V. E. Bening ◽  
V. Yu. Korolev ◽  
A. E. Petrov ◽  
K. A. Sarksyan ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Turbulent Transport ◽  
Transport Processes ◽  
New Approach

INFERENCE VERSUS IMPRINT IN CLIMATE MODELING

2002 ◽  
Vol 05 (01) ◽  
pp. 73-89 ◽  
Author(s):  
A. J. PALMER ◽  
T. L. SCHNEIDER ◽  
L. A. BENJAMIN
Keyword(s):  
Climate Model ◽  
Climate Modeling ◽  
Turbulent Transport ◽  
Eddy Diffusivity ◽  
Transport Processes ◽  
Modeling Framework ◽  
Transport Models ◽  
Complex Processes ◽  
Single Column ◽  
Comparable Performance

A statistical inference method known as ε-machine reconstruction is introduced as a modeling procedure for turbulent transport processes in a climate model. Observational data on the atmospheric boundary layer obtained with a radar wind profiler, a radio-acoustic sounding system, and a Raman lidar system was assembled to construct this type of model for use within the unresolved (sub-grid) scales of a numerical climate model. An ensemble of 500 single-column model runs using the inferred sub-grid turbulent transport models demonstrated comparable performance to an identical ensemble of runs using the standard, eddy-diffusivity parametrizations for the turbulent transport. The primary advantages of the ε-machine models are that they are a less biased modeling framework for complex processes such as turbulent transport, and that they are more memory efficient.

scholarly journals An experimental investigation and statistical analysis of turbulent swirl flow in a straight pipe

2017 ◽  
Vol 21 (suppl. 3) ◽  
pp. 691-704 ◽  
Author(s):  
Milan Lecic ◽  
Aleksandar Cocic ◽  
Jela Burazer
Keyword(s):  
Velocity Field ◽  
Turbulent Transport ◽  
Field Measurements ◽  
Viscous Sublayer ◽  
Swirl Flow ◽  
Transport Processes ◽  
Statistical Characteristics ◽  
Straight Pipe ◽  
Measured Velocity ◽  
Swirl Flows

This paper presents results of our own velocity field measurements in a straight pipe swirl flow. These studies were conducted using an originally designed hot wire probe. Due to the specially tailored shape of the probe, it was possible to get four measurement points in the viscous sublayer. The time-averaged velocity field and the statistical moments of the second and third order are calculated based on the measured velocity components. Mathematical and physical interpretations of statistical characteristics and structures of turbulent swirl flow in the time domain are presented. On the basis of these results, deeper insight into turbulent transport processes can be obtained, as well as useful conclusions necessary for turbulent swirl flows modeling.

Investigation of the Fuel Distribution in a Shockless Explosion Combustor

2020 ◽  
Author(s):  
Fatma Cansu Yücel ◽  
Fabian Habicht ◽  
Alexander Jaeschke ◽  
Finn Lückoff ◽  
Kilian Oberleithner ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Concentration Profile ◽  
Optical Measurement ◽  
Turbulent Transport ◽  
Measurement Techniques ◽  
Transport Processes ◽  
Turbulent Pipe Flow ◽  
Tunable Diode Laser ◽  
Fuel Concentration ◽  
Fuel Profile

Abstract Shockless explosion combustion is a promising concept for implementing pressure gain combustion into a conventional gas turbine cycle. This concept aims for a quasi-homogeneous autoignition that induces a moderate rise in pressure. By this, considerable losses due to entropy generation by inherent shock waves of detonation-based concepts can be avoided. Since the ignition is not triggered by an external source but driven by chemical kinetics only, the homogeneity of the autoignition is very sensitive to local perturbations in equivalence ratio, temperature, and pressure that produce undesired local premature ignition. Therefore, the precise injection of a well-defined fuel profile into an convecting air flow is crucial to ensure a quasi-homogeneous ignition of the entire flammable mixture. The objective of this work is to demonstrate that the injected fuel profile is preserved throughout the entire measurement section. For this, two different control trajectories are investigated. Optical measurement techniques are used to illustrate the effect of turbulent transport and dispersion caused by boundary layer effects on the fuel concentration profile inside the combustor. Results from line-of-sight measurements by tunable diode laser absorption spectroscopy indicate that the transport of the fuel-air mixture is dominated by turbulent diffusion. However, comparisons to numerical calculations reveal the effect of dispersion towards the bounds of the fuel concentration profile. The spatially resolved distributions of the fuel concentration inside the combustor gained from acetone planar laser induced fluorescence replicates a typical velocity distribution of turbulent pipe flow in radial direction visualizing boundary layer effects. Comparing both methods provide deep insights into the transport processes that have an impact on the operation of the shockless explosion combustor.

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