On the expansion of a gas into vacuum

1962 ◽  
Vol 13 (1) ◽  
pp. 101-119 ◽  
Author(s):  
H. P. Greenspan ◽  
D. S. Butler
Keyword(s):  
Spherical Cavity ◽  
Continuum Model ◽  
Rigid Wall ◽  
Uniform Pressure ◽  
Plane Front ◽  
Vacuum Interface

A study is made of the flow into vacuum of a gas initially at rest in a state of uniform pressure and density; the analysis is based on a continuum model. Among the topics discussed are the motion of the gas-vacuum interface, the reflexion of a plane front off a rigid wall, the propagation of compressive waves within such expansions, the escape from a sphere and the collapse of a spherical cavity.

The effect of a pressure wave on a rigid wall covered with a porous layer

2006 ◽  
Vol 4 ◽  
pp. 156-165 ◽  
Author(s):  
S.V. Lukin
Keyword(s):  
Porous Layer ◽  
Pressure Wave ◽  
Continuum Model ◽  
Solid Wall ◽  
Rigid Wall ◽  
Saturated Liquid ◽  
Wave Processes ◽  
Porous Substance ◽  
Step Type ◽  
Type Pressure

The influence of the non-stationary Basset-Boussinesq forces on the reflection of a step-type pressure wave from a solid surface coated with a porous layer, a saturated liquid or a gas is investigated. The study of wave processes is carried out within the framework of the multi-velocity continuum model. A comparative analysis of the properties of porous screens saturated with a liquid or gas is carried out. The degree of influence of the non-stationary Basset-Boussinesq force on reflection of a wave from a solid wall covered with a porous substance is established.

Asymmetric Cavitation Bubble Collapse

1973 ◽  
Vol 95 (1) ◽  
pp. 29-37 ◽  
Author(s):  
T. M. Mitchell ◽  
F. G. Hammitt
Keyword(s):  
Rigid Wall ◽  
The Body ◽  
Bubble Collapse ◽  
Fluid Viscosity ◽  
Uniform Pressure ◽  
Vapor Bubbles ◽  
Bubble Wall ◽  
Spherical Bubble ◽  
Spherical Bubbles ◽  
Wall Proximity

Numerical results describing the asymmetric collapse of vapor bubbles in an incompressible liquid for various cases of axial symmetry involving boundary conditions which prevent the maintenance of spherical symmetry are presented using a modified Marker-and-Cell (MAC) technique. The effects of fluid viscosity within the body of the liquid are considered, and upon the wall in the wall-proximity problem, but its effects at the bubble wall boundary are neglected. The cases studied include originally stationary spherical bubbles in a pressure gradient, an originally spherical bubble moving through an otherwise stationary liquid at uniform pressure, and an initially spherical bubble in a liquid at uniform pressure close to a rigid wall. This latter case applies approximately also to two identical bubbles collapsing in an infinite fluid in proximity to each other as shown by photographs here included. In all those cases which involve originally spherical bubbles, the bubble collapses in such a way as to form a jet.

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

Fluid Dynamics of Spherical Cavity Reactors

1987 ◽  
Author(s):  
Isaac Maya ◽  
Craig Christy ◽  
Mohamad Dagher ◽  
Thomas Kim ◽  
J. Richard Williams
Keyword(s):  
Fluid Dynamics ◽  
Spherical Cavity
Sign in / Sign up

Export Citation Format

Share Document