Stabilization of Wave Formation on a Contact Boundary of Metal Layers at an Oblique Impact during Kelvin - Helmholtz Instability Development

By means of the formation of vortices in the nonlinear phase, the Kelvin Helmholtz instability is able to redistribute the flux of energy of the solar wind that flows parallel to the magnetopause. The energy transport associated with the Kelvin Helmholtz instability contributes significantly to the magnetosphere and magnetosheath dynamics, in particular at the flanks of the magnetopause where the presence of a magnetic field perpendicular to the velocity flow does not inhibit the instability development. By means of a 2D two-fluid simulation code, the behavior of the Kelvin Helmholtz instability is investigated in the presence of typical conditions observed at the magnetopause. In particular, the energy penetration in the magnetosphere is studied as a function of an important parameter such as the solar wind velocity. The influence of the density jump at the magnetopause is also discussed.

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Numerical Simulation of a High-Speed Impact of Metal Plates Using a Three-Fluid Model

Metals ◽

10.3390/met11081233 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1233

Author(s):

Petr Chuprov ◽

Pavel Utkin ◽

Svetlana Fortova

Keyword(s):

High Speed ◽

Steel Plate ◽

Ambient Air ◽

Wave Formation ◽

Contact Boundary ◽

Multidimensional Case ◽

Rarefaction Waves ◽

High Speed Impact ◽

Lead Plate ◽

Metal Plates

The process of wave formation at the contact boundary of colliding metal plates is a fundamental basis of explosive welding technology. In this case, the metals are in a pseudo-liquid state at the initial stages of the process, and from a mathematical point of view, a wave formation process can be described by compressible multiphase models. The work is devoted to the development of a three-fluid mathematical model based on the Baer–Nunziato system of equations and a corresponding numerical algorithm based on the HLL and HLLC methods, stiff pressure, and velocity relaxation procedures for simulation of the high-speed impact of metal plates in a one-dimensional statement. The problem of collision of a lead plate at a speed of 500 m/s with a resting steel plate was simulated using the developed model and algorithm. The problem statement corresponded to full-scale experiments, with lead, steel, and ambient air as three phases. The arrival times of shock waves at the free boundaries of the plates and rarefaction waves at the contact boundary of the plates, as well as the acceleration of the contact boundary after the passage of rarefaction waves through it, were estimated. For the case of a 3-mm-thick steel plate and a 2-mm-thick lead plate, the simulated time of the rarefaction wave arrival at the contact boundary constituted 1.05 μs, and it was in good agreement with the experimental value 1.1 μs. The developed numerical approach can be extended to the multidimensional case for modeling the instability of the contact boundary and wave formation in the oblique collision of plates in the Eulerian formalism.

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About formation of contact boundary between two metals in unsteady conditions of oblique impact

10.1063/1.1303685 ◽

2000 ◽

Author(s):

Oleg B. Drennov

Keyword(s):

Oblique Impact ◽

Contact Boundary ◽

Unsteady Conditions

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STM of freeze-fracture replicas: Problems and promises

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146187 ◽

1993 ◽

Vol 51 ◽

pp. 68-69

Author(s):

J. T. Woodward ◽

J. A. N. Zasadzinski

Keyword(s):

Scanning Tunneling Microscope ◽

Organic Materials ◽

Freeze Fracture ◽

Atomic Resolution ◽

Scanning Tunneling ◽

Tunneling Microscope ◽

Molecular Scale ◽

Organic Surfaces ◽

Metal Layers ◽

Conductive Surfaces

The Scanning Tunneling Microscope (STM) offers exciting new ways of imaging surfaces of biological or organic materials with resolution to the sub-molecular scale. Rigid, conductive surfaces can readily be imaged with the STM with atomic resolution. Unfortunately, organic surfaces are neither sufficiently conductive or rigid enough to be examined directly with the STM. At present, nonconductive surfaces can be examined in two ways: 1) Using the AFM, which measures the deflection of a weak spring as it is dragged across the surface, or 2) coating or replicating non-conductive surfaces with metal layers so as to make them conductive, then imaging with the STM. However, we have found that the conventional freeze-fracture technique, while extremely useful for imaging bulk organic materials with STM, must be modified considerably for optimal use in the STM.

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