Determining energy cascade rate in magnetohydrodynamics by third-order law
| Author(s) | Wang, Yanwen | |
| Date Accessioned | 2023-02-17T13:47:11Z | |
| Date Available | 2023-02-17T13:47:11Z | |
| Publication Date | 2022 | |
| SWORD Update | 2022-09-21T16:09:04Z | |
| Abstract | Energy dissipation, which is the conversion of kinetic energy to internal energy in a fluid, has long been considered a crucial and complex subject in plasma physics. In turbulent systems of plasmas, energy is transferred from large scales to small scales, and the process is called energy cascade. The study of the energy cascade process is a complex area in laboratory and space plasma physics. Various methods are developed to explore the turbulent dynamic of plasmas and evaluate the energy dissipation rate. Kolmogorov's four-fifths law in hydrodynamics has been extended to many systems of interest, such as magnetohydrodynamics (MHD), and compressible flows of magneto-fluids and ordinary fluids. It is understood that implementations may be limited by the quantity of available data and by the lack of turbulence symmetry. Assessment of the accuracy and feasibility of such Yaglom-like relations is most effectively accomplished by examining the von Karman--Howarth equation in increment form, a framework from which the Yaglom laws are derived as asymptotic approximations. In this study, we examine the Yaglom law, or third-order law for incompressible ideal MHD, which is the approximation of plasma under specific length scales and time scales. The simplest versions of the third-order law rely on the assumption of isotropy and the presence of a well-defined inertial range, while related procedures generalize the same idea to arbitrary rotational symmetries. The simplified third-order law is usually used in single spacecraft measurements to study the heating and acceleration in the solar wind. Conditions for obtaining the exact values of the dissipation rate from these laws based on several sampling and fitting strategies are investigated using results from simulations in our study. The strategies of estimating the energy dissipation rate by third-order law and the directional-averaging method we address are of particular relevance to the sampling of solar wind turbulence by one or more spacecraft. | |
| Advisor | Matthaeus, William H. | |
| Degree | M.S. | |
| Department | University of Delaware, Department of Physics and Astronomy | |
| Unique Identifier | 1370335886 | |
| URL | https://udspace.udel.edu/handle/19716/32317 | |
| Language | en | |
| Publisher | University of Delaware | |
| URI | https://login.udel.idm.oclc.org/login?url=https://www.proquest.com/dissertations-theses/determining-energy-cascade-rate/docview/2723548554/se-2?accountid=10457 | |
| Keywords | Magnetohydrodynamics | |
| Keywords | Plasma turbulence | |
| Keywords | Solar wind | |
| Title | Determining energy cascade rate in magnetohydrodynamics by third-order law | |
| Type | Thesis |