A5044524532- Laser-Plasma Interactions and Diagnostics
- Particle Dynamics in Fluid Flows
- Computational Fluid Dynamics and Aerodynamics
- Gas Dynamics and Kinetic Theory
- Fluid Dynamics and Turbulent Flows
- Combustion and Detonation Processes
- Magnetic confinement fusion research
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Rheology and Fluid Dynamics Studies
- Combustion and flame dynamics
- Fluid Dynamics and Heat Transfer
- Polymer crystallization and properties
- Laser-induced spectroscopy and plasma
- Geomagnetism and Paleomagnetism Studies
- Energetic Materials and Combustion
- Plasma and Flow Control in Aerodynamics
- Laser Design and Applications
- Superconducting Materials and Applications
- Heat Transfer and Boiling Studies
- Quantum chaos and dynamical systems
- Inhalation and Respiratory Drug Delivery
- Material Properties and Processing
- Nuclear Physics and Applications
- Fire dynamics and safety research
University of Wisconsin–Madison
2011-2023
Madison Area Technical College
2021
Fusion (United States)
2000-2006
University of Portsmouth
2003
Texas A&M University
1992-1994
When a shock wave propagates through medium of nonuniform thermodynamic properties, several processes occur simultaneously that alter the geometry and state medium. These include compression acceleration medium, refraction shock, vorticity generation within The interaction with cylinder or sphere (both referred to as bubble in this review) is simplest configuration which all these take place can be studied detail. Shock leads an initial distortion bubble, followed by formation vortex pair...
The morphology and time-dependent integral properties of the multifluid compressible flow resulting from shock–bubble interaction in a gas environment are investigated using series three-dimensional multifluid-Eulerian simulations. bubble consists spherical volume radius 2.54 cm (128 grid points), which is accelerated by planar shock wave. Fourteen scenarios considered: four pairings, including Atwood numbers −0.8 < A 0.7, strengths 1.1 M ≤ 5.0. data queried at closely spaced time...
The interaction of a planar shock wave with spherical bubble in divergent shock-refraction geometry is studied here using tube experiments and numerical simulations. particular case helium ambient air or nitrogen (A≈−0.8) considered, for 1.4&lt;M&lt;3.0. Experimental laser diagnostics three-dimensional multifluid Eulerian simulations clearly resolve features arising as consequence refraction, including the formation long-lived primary vortex ring, well counter-rotating secondary...
A universal scaling law for the Richtmyer–Meshkov instability is validated with experimental results covering a wide range of density ratios and shock strengths. These include first membraneless, gas-phase, interface experiments A&gt;0.5 M&gt;1.5. The shock-accelerated, sinusoidal are conducted in vertical tube large square cross section cover parameter space: 0.29&lt;A&lt;0.95, 1.1&lt;M&lt;3, 3.1×104&lt;Re&lt;1.4×107. Results provide growth-rate data...
Experiments to study the compression and unstable evolution of an isolated soap-film bubble containing helium, subjected a strong planar shock wave ($M=2.95$) in ambient nitrogen, have been performed vertical tube square internal cross section using laser diagnostics. The early phase interaction process is dominated by formation primary vortex ring due baroclinic source vorticity deposited during shock-bubble interaction, mass transfer from body ring. late time (long after interaction)...
The Richtmyer-Meshkov instability is experimentally investigated in a vertical shock tube using new type of broadband initial condition imposed on an interface between helium-acetone mixture and argon (A = 0.7). created by first setting up gravitationally stable stagnation plane the gases then injecting same two horizontally at to create shear layer. perturbations along layer statistically repeatable condition. accelerated M 1.6 planar wave, development ensuing turbulent mixing laser induced...
The Richtmyer–Meshkov instability (RMI) is experimentally investigated in a vertical shock tube using broadband initial condition imposed on an interface between helium–acetone mixture and argon (.
A free-falling, spherical, soap-film bubble filled with argon is subjected to a planar M=2.88 shock in atmospheric nitrogen; vorticity deposited on the surface of during interaction, and Richtmyer-Meshkov instability ensues. The geometrical development shocked diagnosed laser sheet imaging slice showing two cross sections both major vortex ring secondary revealed experimentally for first time. Quantitative measurements experimental data include velocity defect, subsequent circulation...
AbstractThe long-range goal of the Z-Pinch IFE program is to produce an economically-attractive power plant using high-yield z-pinch-driven targets (~3GJ) with low rep-rate per chamber (~0.1 Hz). The present mainline choice for a uses LTD (Linear Transformer Driver) repetitive pulsed driver, Recyclable Transmission Line (RTL), dynamic hohlraum target, and thick-liquid wall chamber. RTL connects driver directly made from frozen coolant or material that easily separable (such as carbon steel)....
The Richtmyer–Meshkov instability (RMI) is experimentally investigated in a vertical shock tube using broadband initial condition imposed on an interface between helium–acetone mixture and argon (Atwood number $A\approx 0.7$ ). In the present work, shear layer introduced at to serve as statistically repeatable, RMI, density accelerated by either $M=1.6$ or $M=2.2$ planar wave. development of ensuing mixing simultaneous laser-induced fluorescence (PLIF) particle image velocimetry (PIV). PLIF...
The unique properties of magnetic fluids are exploited to create a static interface between two in the context studying Rayleigh-Taylor (RT) driven mixing. Paramagnetic have previously been used for this phenomenon [Z. Huang, Phys. Rev. Lett. 99, 204502 (2007)], as ferrofluids [G. Pacitto, E 62, 7941 (2000)], but we propose using magnetorheological instead attain better control initial condition. As motivation technique is quantify effects condition on late time behavior RT instability, it...
The kinetic rate equation proposed by Mewis and Denn (1983) for their structural network model is found to predict accurately the large amplitude oscillatory shear behavior of molten low density polyethylene IUPAC X. Spectral analysis used compare predictions several equations. Frequency versus strain maps are constructed examine each harmonic stress response predicted Mewis–Denn model. A Pipkin diagram calculated this using contours third harmonic.
Results are presented from a series of experiments and simulations, studying the interaction planar shock wave (2.0⩽M⩽5.0) with discrete gas inhomogeneity. Experiments computations confirm that phenomenology shock–bubble interactions is fundamentally altered by changes in Atwood number. In case low number, late time flow field dominated coherent vortical structures, whereas high shocked bubble effectively reduced to small core compressed fluid, which trails behind plume-like structure...
The Richtmyer–Meshkov instability (Richtmyer, Commun. Pure Appl. Maths , vol. 13, issue 2, 1960, pp. 297–319; Meshkov, Fluid Dyn. 4, 5, 1972, 101–104) of a twice-shocked gas interface is studied using both high spatial resolution single-shot (SS) and lower resolution, time-resolved, high-speed (HS) simultaneous planar laser-induced fluorescence particle image velocimetry in the Wisconsin Shock Tube Laboratory's vertical shock tube. initial condition (IC) shear layer with broadband diffuse...
Abstract A sliding plate rheometer has been developed to measure the normal thrust of a molten plastic in large amplitude oscillatory shear . The is significant nonlinear effect that previously unobtainable. Normal measurements may now be used help understand and characterize viscoelastic behavior inherent most plastics new rhemoeter incorporates piezoelectric pressure transducer very stiff minimizes compliance. with cone rheometers are made by measuring total force on (or cone) subject...
Abstract Giacomin and Oakley (1991) have shown that an upper convected Maxwell model with a structure‐dependent relaxation spectrum incorporating the three‐parameter kinetic rate equation proposed by Mewis Denn (1983) works remarkably well for molten LDPE in large‐amplitude oscillatory shear (LAOS). In search simpler framework interpreting LAOS based on network theory, four nonlinear, differential constitutive equations, each less than three parameters, were evaluated. These models are...