An energy and momentum conserving collisional bracket for the guiding-centre Vlasov–Maxwell–Landau model

2021 ◽  
Vol 87 (4) ◽  
Author(s):  
Riccardo N. Iorio ◽  
Eero Hirvijoki
Keyword(s):  
Simple Form ◽  
Collision Operator ◽  
Momentum Conservation ◽  
Landau Model ◽  
Coulomb Collisions ◽  
Entropy Dissipation ◽  
Collisional Dynamics ◽  
Equilibrium Distributions ◽  
H Theorem ◽  
Energy And Momentum

This paper proposes a metric bracket for representing Coulomb collisions in the so-called guiding-centre Vlasov–Maxwell–Landau model. The bracket is manufactured to preserve the same energy and momentum functionals as does the Vlasov–Maxwell part and to simultaneously satisfy a revised version of the H-theorem, where the equilibrium distributions with respect to collisional dynamics are identified as Maxwellians. This is achieved by exploiting the special projective nature of the Landau collision operator and the simple form of the system's momentum functional. A discussion regarding a possible extension of the results to electromagnetic drift-kinetic and gyrokinetic systems is included. We anticipate that energy conservation and entropy dissipation can always be manufactured whereas guaranteeing momentum conservation is a delicate matter yet to be resolved.

scholarly journals The Impact of Teaching Physics via Modeling on Modifying Alternative Conception of Energy and Momentum Conservation among 11th Grade Female Students

2017 ◽  
Vol 11 (1) ◽  
pp. 53
Author(s):  
Abdulah K. Ambusaidi ◽  
Rahma M. Al Sabri
Keyword(s):  
Science Teachers ◽  
Momentum Conservation ◽  
Female Students ◽  
Scientific Models ◽  
Significant Difference ◽  
Energy And Momentum ◽  
The Impact ◽  
Teaching Physics ◽  
Experimental Group ◽  
11Th Grade

This study investigated the impact of teaching physics via modeling on theacquisition of energy and momentum conservation concepts. The sample consisted of 91 female students selected from 11th grade female students in two schools in Al-Dakhiliyah Governorate in Oman. The experimental group (n = 45) was taught via the modeling method, and the control group (n = 46) was taught using a traditional method. The study lasted six weeks during the second semester of the academic year 2013/2014. A teacher guide for teaching by models was designed and validated by a group of experts. To measure the acquisition of physics concepts, energy and momentum, an achievement test was used. The test consisted of 20 multiple-choice questions. Its reliability was measured by test-retest method (r = 0.79). The results revealed a statistically significant difference (p < .05) between the means of the experimental and control groups in favor of the experimental group. The study recommends that science teachers ought to use models and modeling in their teaching. Workshops to train supervisors, in-service teachers and pre-service teachers in the construction and development of scientific models need to be conducted

scholarly journals New results on energy and momentum conservation for particle emission in A+A collisions at not too high energies

2017 ◽  
Author(s):  
Andrzej Rybicki ◽  
Miroslaw Kielbowicz ◽  
Antoni Szczurek ◽  
Iwona Anna Sputowska
Keyword(s):  
Momentum Conservation ◽  
Particle Emission ◽  
High Energies ◽  
Energy And Momentum

scholarly journals Numerical investigations of stainless steel melt motions on the surface of uranium dioxide

2019 ◽  
Vol 196 ◽  
pp. 00005 ◽  
Author(s):  
Eduard V. Usov ◽  
Pavel D. Lobanov ◽  
Ilya A. Klimonov ◽  
Alexander E. Kutlimetov ◽  
Anton A. Butov ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Uranium Dioxide ◽  
Momentum Conservation ◽  
Mass Energy ◽  
Numerical Investigations ◽  
Fuel Rod ◽  
The Core ◽  
Fuel Pin ◽  
Energy And Momentum ◽  
Coolant Velocity

The paper contains the results of numerical simulation of stainless steel melt motions on the surface of uranium dioxide. The investigations are performed for purposes of understanding of the fuel rod behavior during the core disruptive accident in the fast reactors. The systems of mass, energy and momentum conservation equations are solved to simulate melt motion on the surface of the fuel pin. Heat transfer and friction between melt and pin's surface and melt and coolant flow are taken into consideration. The dependences of mass of the melt and the features of the melt motion on coolant velocity and contact angle between melt and surface of the fuel rod are presented.

scholarly journals Laguerre–Hermite pseudo-spectral velocity formulation of gyrokinetics

2018 ◽  
Vol 84 (1) ◽  
Author(s):  
N. R. Mandell ◽  
W. Dorland ◽  
M. Landreman
Keyword(s):  
Three Dimensional ◽  
Collision Operator ◽  
Zonal Flow ◽  
Phase Mixing ◽  
Final Model ◽  
Nonlinear Phase ◽  
Wide Range ◽  
H Theorem ◽  
Spectral Velocity ◽  
Pseudo Spectral

First-principles simulations of tokamak turbulence have proven to be of great value in recent decades. We develop a pseudo-spectral velocity formulation of the turbulence equations that smoothly interpolates between the highly efficient but lower resolution three-dimensional (3-D) gyrofluid representation and the conventional but more expensive 5-D gyrokinetic representation. Our formulation is a projection of the nonlinear gyrokinetic equation onto a Laguerre–Hermite velocity-space basis. We discuss issues related to collisions, closures and entropy. While any collision operator can be used in the formulation, we highlight a model operator that has a particularly sparse Laguerre–Hermite representation, while satisfying conservation laws and the H theorem. Free streaming, magnetic drifts and nonlinear phase mixing each give rise to closure problems, which we discuss in relation to the instabilities of interest and to free energy conservation. We show that the model is capable of reproducing gyrokinetic results for linear instabilities and zonal flow dynamics. Thus the final model is appropriate for the study of instabilities, turbulence and transport in a wide range of geometries, including tokamaks and stellarators.

An Action-at-a-Distance Theory of Gravitation

1971 ◽  
Vol 49 (2) ◽  
pp. 201-217 ◽  
Author(s):  
A. B. Volkov
Keyword(s):  
Momentum Conservation ◽  
Dielectric Dispersion ◽  
Interaction Theory ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Vector Interaction ◽  
Perihelion Advance ◽  
Theory Of Gravitation ◽  
Action At A Distance ◽  
Energy And Momentum

An action-at-a-distance theory is formulated as a possible alternative to the general theory of relativity. The observed gravitational frequency shift and light bending are obtained by photon energy and momentum conservation effects and gravitational–electromagnetic phenomena are interpreted in analogy with the quantum theory of dielectric dispersion. The observed perihelion advance of Mercury is obtained by a combined scalar and vector interaction theory of the Wheeler–Feynman type. The vector interaction is no longer excluded by conventional field theoretic arguments.

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