scholarly journals Reflecting laser-driven shocks in diamond in the megabar pressure range

2021 ◽  
Vol 9 ◽  
Author(s):  
K. Jakubowska ◽  
D. Mancelli ◽  
R. Benocci ◽  
J. Trela ◽  
I. Errea ◽  
...  
Keyword(s):  
Pressure Range ◽  
Equations Of State ◽  
Shock Velocity ◽  
Experimental Results ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
Planar Shock ◽  
Hydrodynamical Simulations ◽  
Metal Layers ◽  
Target Design

Abstract In this work we present experimental results on the behavior of diamond at megabar pressure. The experiment was performed using the PHELIX facility at GSI in Germany to launch a planar shock into solid multi-layered diamond samples. The target design allows shock velocity in diamond and in two metal layers to be measured as well as the free surface velocity after shock breakout. As diagnostics, we used two velocity interferometry systems for any reflector (VISARs). Our measurements show that for the pressures obtained in diamond (between 3 and 9 Mbar), the propagation of the shock induces a reflecting state of the material. Finally, the experimental results are compared with hydrodynamical simulations in which we used different equations of state, showing compatibility with dedicated SESAME tables for diamond.

Messung des Chapman-Jouguet-Druckes mit Röntgen-Absorption

1981 ◽  
Vol 36 (5) ◽  
pp. 437-442
Author(s):  
K. Hollenberg ◽  
H.-R. Kleinhanß ◽  
G. Reiling
Keyword(s):  
Free Surface ◽  
Pressure Range ◽  
Detonation Front ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
High Explosives ◽  
X Ray ◽  
X Ray Absorption

Abstract The Chapman Jouguet pressure of some high explosives is measured by X-ray absorption giving the density behind the detonation front. An accuracy of 2 - 3% was achieved in the pressure range of 200 kbar. The pressures are considerably lower than comparable results of other authors obtained by the free surface velocity method or similar techniques.

scholarly journals Mathematical modelling of the overflowing cylinder experiment

2003 ◽  
Vol 474 ◽  
pp. 275-298 ◽  
Author(s):  
P. D. HOWELL ◽  
C. J. W. BREWARD
Keyword(s):  
Free Surface ◽  
Surfactant Concentration ◽  
Dynamic Properties ◽  
Vertical Cylinder ◽  
Surfactant Solution ◽  
Surface Concentration ◽  
Experimental Results ◽  
Surface Velocity ◽  
Experimental Apparatus ◽  
Finite Distance

The overflowing cylinder (OFC) is an experimental apparatus designed to generate a controlled straining flow at a free surface, whose dynamic properties may then be investigated. Surfactant solution is pumped up slowly through a vertical cylinder. On reaching the top, the liquid forms a flat free surface which expands radially before over flowing down the side of the cylinder. The velocity, surface tension and surfactant concentration on the expanding free surface are measured using a variety of non-invasive techniques.A mathematical model for the OFC has been previously derived by Breward et al. (2001) and shown to give satisfactory agreement with experimental results. However, a puzzling indeterminacy in the model renders it unable to predict one scalar parameter (e.g. the surfactant concentration at the centre of the cylinder), which must be therefore be taken from the experiments.In this paper we analyse the OFC model asymptotically and numerically. We show that solutions typically develop one of two possible singularities. In the first, the surface concentration of surfactant reaches zero a finite distance from the cylinder axis, while the surface velocity tends to infinity there. In the second, the surfactant concentration is exponentially large and a stagnation point forms just inside the rim of the cylinder. We propose a criterion for selecting the free parameter, based on the elimination of both singularities, and show that it leads to good agreement with experimental results.

scholarly journals Identification of Ellis rheological law from free surface velocity

2019 ◽  
Vol 263 ◽  
pp. 15-23 ◽  
Author(s):  
Abdulrahman Al-Behadili ◽  
Mathieu Sellier ◽  
James N. Hewett ◽  
Roger I. Nokes ◽  
Miguel Moyers-Gonzalez
Keyword(s):  
Free Surface ◽  
Surface Velocity ◽  
Free Surface Velocity

Evaluation of Marangoni convection and free surface velocity of molten tungsten for tungsten divertor

2019 ◽  
Vol 140 ◽  
pp. 117-122 ◽  
Author(s):  
Kohei Hamaguchi ◽  
Eiji Hoashi ◽  
Takafumi Okita ◽  
Kenzo Ibano ◽  
Yoshio Ueda
Keyword(s):  
Free Surface ◽  
Marangoni Convection ◽  
Surface Velocity ◽  
Free Surface Velocity

scholarly journals Discussion on the physical meaning of free surface velocity curve in ductile spallation

2015 ◽  
Vol 64 (3) ◽  
pp. 034601
Author(s):  
Pei Xiao-Yang ◽  
Peng Hui ◽  
He Hong-Liang ◽  
Li Ping
Keyword(s):  
Free Surface ◽  
Physical Meaning ◽  
Velocity Curve ◽  
Surface Velocity ◽  
Free Surface Velocity

scholarly journals Prediction of 10-fold coordinated TiO2 and SiO2 structures at multimegabar pressures

2015 ◽  
Vol 112 (22) ◽  
pp. 6898-6901 ◽  
Author(s):  
Matthew J. Lyle ◽  
Chris J. Pickard ◽  
Richard J. Needs
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Electronic Properties ◽  
First Principles ◽  
Pressure Range ◽  
Extrasolar Planets ◽  
Equations Of State ◽  
Space Group ◽  
P Type ◽  
Pressure Phase

We predict by first-principles methods a phase transition in TiO2 at 6.5 Mbar from the Fe2P-type polymorph to a ten-coordinated structure with space group I4/mmm. This is the first report, to our knowledge, of the pressure-induced phase transition to the I4/mmm structure among all dioxide compounds. The I4/mmm structure was found to be up to 3.3% denser across all pressures investigated. Significant differences were found in the electronic properties of the two structures, and the metallization of TiO2 was calculated to occur concomitantly with the phase transition to I4/mmm. The implications of our findings were extended to SiO2, and an analogous Fe2P-type to I4/mmm transition was found to occur at 10 TPa. This is consistent with the lower-pressure phase transitions of TiO2, which are well-established models for the phase transitions in other AX2 compounds, including SiO2. As in TiO2, the transition to I4/mmm corresponds to the metallization of SiO2. This transformation is in the pressure range reached in the interiors of recently discovered extrasolar planets and calls for a reformulation of the equations of state used to model them.

Free Surface, Velocity Gradient Flow Past Hemisphere

1970 ◽  
Vol 96 (7) ◽  
pp. 1485-1502
Author(s):  
Gordon H. Flammer ◽  
J. Paul Tullis ◽  
Earl S. Mason
Keyword(s):  
Free Surface ◽  
Velocity Gradient ◽  
Gradient Flow ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
Flow Past

Jet Impingement of a Non-Newtonian Fluid

2006 ◽  
Author(s):  
Jiangang Zhao ◽  
Roger E. Khayat
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Hydraulic Jump ◽  
Similarity Solutions ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
Viscous Boundary Layer ◽  
Boundary Layer Region ◽  
Layer Region ◽  
Viscous Boundary

The similarity solutions are presented for the wall flow which is formed when a smooth planar jet of power-law fluids impinges vertically on to a horizontal plate, and spreads out in a thin layer bounded by a hydraulic jump. This problem is formulated analogous to radial jet flow problem and the solution procedure is accounted for by means of similarity solution of the boundary-layer equation [1] for Newtonian fluids. For the convenience of analysis, the flow may be divided into three regions, namely a developing boundary-layer region, a fully viscous boundary-layer region, and a hydraulic jump region. The similarity solutions of the film thickness and free surface velocity in fully viscous boundary-layer region include unknown constant L, which is solved numerically and approximately in the developing boundary-layer flow region. Comparison between the numerical and approximate solutions leads generally to good agreement, except for severely shear-thinning fluids. The boundary-layer solution depends on two parameters: power-law index n and α, the dimensionless flow parameters. The effect of α on film thickness and free surface velocity is investigated. The relations between the position of the hydraulic jump and dimensionless flow parameter are obtained and the effect of α on the position of the jump is presented.

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