Numerical simulation and analysis of magnetically dominated MHD bow shock flows with applications in space physics / Hans De Sterck.

By: Contributor(s): Series: NCAR cooperative thesis ; 167 | NCAR cooperative thesis ; 167.Boulder, CO : National Center for Atmospheric Research (NCAR), 1999Description: 324 p. : ill. (some col.) ; 23 cmContent type:
  • text
Media type:
  • unmediated
Carrier type:
  • volume
Subject(s): Dissertation note: Thesis (Ph. D.)--Katholieke Universiteit Leuven, 1999. Summary: New results are presented on the topology of stationary bow shock flows in magnetohydrodynamic (MHD) plasmas. The problem is studied via numerical simulations in the classical setting of stationary bow shock flow around perfectly conducting rigid cylinders, spheres and paraboloids. It is shown that when the flow upstream from the obstacle is magnetically dominated, the bow shock flows exhibit a surprisingly complex topology involving multiple interacting shocks with segments of various MHD shock types. The upstream flow is called magnetically dominated-as opposed to pressure- dominated-when the magnetic field is strong and magnetic forces dominate over thermal and dynamic pressure effects such that the intrinsically magnetic phenomenon of the switch-on shock is encountered on the bow shock front. The new complex topology is very different from the traditional single-front topology which arises for pressure-dominated MHD bow shock flows. An in-depth analysis of the simulation results is given using the characteristic properties of the MHD equations, which confirms the presence of intermediate shocks and compound shocks in the two-dimensional (2D) and three- dimensional (3D) simulation results. In recent years there has been much debate about the existence of these types of waves. Until recently they have mainly been studied in one-dimensional systems. The simulation results presented seem to be the first clear confirmation of their existence in 2D and 3D. It is described how a robust and accurate numerical code has been developed for simulation of MHD flows with shocks. The PAR-MA (PARallel MAgnetohydrodynamics) code solves the mathematically well-behaved MHD equations on massively parallel computers using advanced numerical techniques. It is shown through careful validation studies that the numerical scheme produces valid results. The new bow shock topology is relevant for bow shocks in the solar system with magnetically dominated upstream flows. The first example discussed are shocks induced by fast solar coronal mass ejections. The earth's bow shock is the second example. When the solar wind is magnetically dominated-for instance during magnetic cloud events-a secondary slow shock may be formed in the earth's magnetosheath. This may influence the mechanism and timing of the magnetic storms which perturb the space weather.
Holdings
Item type Current library Call number Copy number Status Date due Barcode Item holds
BOOK BOOK NCAR Library Mesa Lab QC718.5 .M36 .S73 1999 1 Available 50583010354490
BOOK BOOK NCAR Library Foothills Lab QC718.5 .M36 .S73 1999 2 Available 50583010362337
Total holds: 0

"NCAR/CT 167."

Thesis (Ph. D.)--Katholieke Universiteit Leuven, 1999.

Includes bibliographical references (p. [309]-324.

New results are presented on the topology of stationary bow shock flows in magnetohydrodynamic (MHD) plasmas. The problem is studied via numerical simulations in the classical setting of stationary bow shock flow around perfectly conducting rigid cylinders, spheres and paraboloids. It is shown that when the flow upstream from the obstacle is magnetically dominated, the bow shock flows exhibit a surprisingly complex topology involving multiple interacting shocks with segments of various MHD shock types. The upstream flow is called magnetically dominated-as opposed to pressure- dominated-when the magnetic field is strong and magnetic forces dominate over thermal and dynamic pressure effects such that the intrinsically magnetic phenomenon of the switch-on shock is encountered on the bow shock front. The new complex topology is very different from the traditional single-front topology which arises for pressure-dominated MHD bow shock flows. An in-depth analysis of the simulation results is given using the characteristic properties of the MHD equations, which confirms the presence of intermediate shocks and compound shocks in the two-dimensional (2D) and three- dimensional (3D) simulation results. In recent years there has been much debate about the existence of these types of waves. Until recently they have mainly been studied in one-dimensional systems. The simulation results presented seem to be the first clear confirmation of their existence in 2D and 3D. It is described how a robust and accurate numerical code has been developed for simulation of MHD flows with shocks. The PAR-MA (PARallel MAgnetohydrodynamics) code solves the mathematically well-behaved MHD equations on massively parallel computers using advanced numerical techniques. It is shown through careful validation studies that the numerical scheme produces valid results. The new bow shock topology is relevant for bow shocks in the solar system with magnetically dominated upstream flows. The first example discussed are shocks induced by fast solar coronal mass ejections. The earth's bow shock is the second example. When the solar wind is magnetically dominated-for instance during magnetic cloud events-a secondary slow shock may be formed in the earth's magnetosheath. This may influence the mechanism and timing of the magnetic storms which perturb the space weather.

Questions? Email library@ucar.edu.

Not finding what you are looking for? InterLibrary Loan.