scholarly journals Laser Ablation of Aluminum Near the Critical Regime: A Computational Gas-Dynamical Model with Temperature-Dependent Physical Parameters

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 300
Author(s):  
Jacopo Terragni ◽  
Antonio Miotello
Keyword(s):  
Laser Ablation ◽  
Laser Energy ◽  
Critical Regime ◽  
Physical Parameters ◽  
Vapor Flow ◽  
Recoil Momentum ◽  
Mass Removal ◽  
Shaped Pulse ◽  
Velocity Pressure

The complexity of the phenomena simultaneously occurring, from the very first instants of high-power laser pulse interaction with the target up to the phase explosion, along with the strong changes in chemical-physical properties of matter, makes modeling laser ablation a hard task, especially near the thermodynamic critical regime. In this work, we report a computational model of an aluminum target irradiated in vacuum by a gaussian-shaped pulse of 20 ns duration, with a peak intensity of the order of GW/cm2. This continuum model covers laser energy deposition and temperature evolution in the irradiated target, along with the mass removal mechanism involved, and the vaporized material expansion. Aluminum was considered to be a case study due to the vast literature on the temperature dependence of its thermodynamic, optical, and transport properties that were used to estimate time-dependent values of surface-vapor quantities (vapor pressure, vapor density, vapor and surface temperature) and vapor gas-dynamical quantities (density, velocity, pressure) as it expands into vacuum. Very favorable agreement is reported with experimental data regarding: mass removal and crater depth due to vaporization, generated recoil momentum, and vapor flow velocity expansion.

scholarly journals Significance of Slippage and Electric Field in Mucociliary Transport of Biomagnetic Fluid

Lubricants ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 48
Author(s):  
Sufian Munawar
Keyword(s):  
Shear Stress ◽  
Flow Direction ◽  
Pressure Rise ◽  
Physical Parameters ◽  
Slippage Effect ◽  
Channel Surface ◽  
Electro Osmosis ◽  
Biomagnetic Fluid ◽  
Velocity Pressure ◽  
Metachronal Waves

Shear stress at the cilia wall is considered as an imperative factor that affects the efficiency of cilia beatings as it describes the momentum transfer between the fluid and the cilia. We consider a visco-inelastic Prandtl fluid in a ciliated channel under electro-osmotic pumping and the slippage effect at cilia surface. Cilia beating is responsible for the stimulation of the flow in the channel. Evenly distributed cilia tend to move in a coordinated rhythm to mobilize propulsive metachronal waves along the channel surface by achieving elliptic trajectory movements in the flow direction. After using lubrication approximations, the governing equations are solved by the perturbation method. The pressure rise per metachronal wavelength is obtained by numerically integrating the expression. The effects of the physical parameters of interest on various flow quantities, such as velocity, pressure gradient, pressure rise, stream function, and shear stress at the ciliated wall, are discussed through graphs. The analysis reveals that the axial velocity is enhanced by escalating the Helmholtz–Smoluchowski velocity and the electro-osmosis effects near the elastic wall. The shear stress at the ciliated boundary elevates with an increase in the cilia length and the eccentricity of the cilia structure.

Pressure Waves in Microscopic Simulations of Laser Ablation Leonid

1998 ◽  
Vol 538 ◽  
Author(s):  
V. Zhigilei ◽  
Barbara J. Garrison
Keyword(s):  
Boundary Condition ◽  
Laser Ablation ◽  
Laser Energy ◽  
Scale Up ◽  
Boundary Region ◽  
Dynamics Simulation ◽  
Pressure Waves ◽  
Absorption Region ◽  
Organic Solids ◽  
Direct Laser

AbstractLaser ablation of organic solids is a complex collective phenomenon that includes processes occurring at different length and time scales. A mesoscopic breathing sphere model developed recently for molecular dynamics simulation of laser ablation and damage of organic solids has significantly expanded the length-scale (up to hundreds of nanometers) and the time-scale (up to nanoseconds) of the simulations. The laser induced buildup of a high pressure within the absorbing volume and generation of the pressure waves propagating from the absorption region poses an additional challenge for molecular-level simulation. A new dynamic boundary condition is developed to minimize the effects of the reflection of the wave from the boundary of the computational cell. The boundary condition accounts for the laser induced pressure wave propagation as well as the direct laser energy deposition in the boundary region.

scholarly journals Preparation and Properties of Superconducting thin Films by Excimer Laser Ablation

1990 ◽  
Vol 191 ◽  
Author(s):  
Michael E. Geusic ◽  
Alan F. Stewart ◽  
Larry R. Pederson ◽  
William J. Weber ◽  
Kenneth R. Marken ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Excimer Laser ◽  
Laser Energy ◽  
Substrate Surface ◽  
Xrd Analysis ◽  
Zero Field ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Excimer Laser Ablation

ABSTRACTExcimer laser ablation with an in situ heat treatment was used to prepare high quality superconducting YBa2Cu3O7−x thin films on (100)-SrTiO3 and (100)-LaAlO3 substrates. A pulsed excimer laser (XeCl; 308 nm) was used to ablate a rotating, bulk YBa2Cu3O7−x target at a laser energy density of 2–3 J/cm2. Based on four-probe dc resistance measurements, the films exhibited superconducting transition temperatures (Tc, midpoint) of 88 and 87K with 2K (90–10%) transition widths for SrTiO3 and LaAlO3, respectively. Transport critical current densities (Jc) measured at 77K were 2 × 106 and 1 × 106 A/cm2 in zero field for SrTiO3 and LaAlO3, respectively. X-ray diffraction (XRD) analysis showed the films to be highly oriented, with the c-axis perpendicular to the substrate surface.

Models For Laser Ablation Mass Removal And Impulse Generation In Vacuum

2010 ◽  
Author(s):  
John E. Sinko ◽  
Don A. Gregory ◽  
Claude Phipps ◽  
Kimiya Komurasaki ◽  
John Sinko
Keyword(s):  
Laser Ablation ◽  
Impulse Generation ◽  
Mass Removal

Preparation ZnO nanoparticles with Different Concentration by Laser Ablation in Liquid

2021 ◽  
Vol 39 (1B) ◽  
pp. 197-202
Author(s):  
Ghufran S. Jaber ◽  
Khawla S. Khashan ◽  
Maha J. Abbas
Keyword(s):  
Particle Size ◽  
Laser Ablation ◽  
Laser Pulse ◽  
Laser Energy ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Pulse Number ◽  
Average Particle ◽  
Zno Nps ◽  
Laser Ablation In Liquid

The effects of varying laser pulse numbers on the fabricated of ZnONPs by pulsed laser ablation in deionized water of Zn-metal are investigated. The Nd: YAG laser at energy 600mJ prepared three samples by change the laser pulse number (100, 150, and 200). The results were collected and examined using an electron scanning microscope, XRD – diffraction, and transmission electron microscope. The result revealed the colloidal spherical shape and the homogeneous composition of the ZnO NPs. The nanoparticles resulted in different concentrations and sized distributions by changing the pulse number of a laser. The average particle size and the mass concentration of particle size increase with an increasing number of laser pulses by fixed the laser energy.

scholarly journals The use of recycled waste products in a sustainable house design - a case study

2018 ◽  
Vol 196 ◽  
pp. 04051
Author(s):  
Agnes Iringová
Keyword(s):  
Physical Parameters ◽  
Renewable Materials ◽  
Recycled Materials ◽  
Waste Products ◽  
Current State ◽  
Waste Production ◽  
House Design ◽  
Family House ◽  
Recycled Waste

The current state of waste production and management in Slovakia. Legislative regulations. Analysis of applying recycled waste products in the construction of sustainable buildings as a substitution of non-renewable materials. The comparison of the physical parameters of recycled materials with non-renewable materials in terms of thermal and fire protection. The construction solution of lightweight building envelopes with a timber supporting system using the thermal insulation and facing made of recycled materials. The model solution of a wood-based family house using recycled waste materials. The comparison of the environmental burden of a standard lightweight sandwich peripheral wall with a recycled waste wall.

scholarly journals Physical Evolution of Solutions in Response to the Contact of Water with Beans: Case Study of Soaking and Boiling

2021 ◽  
pp. 76-95
Author(s):  
J. C. Fopoussi Tuebue ◽  
I. N. Tchinda
Keyword(s):  
Human Urine ◽  
Infiltration Rate ◽  
Physical Parameters ◽  
Phaseolus Vulgaris L ◽  
Specific Behavior ◽  
Cooking Process ◽  
Infiltration Tests ◽  
Present Case Study ◽  
Shed Light

The present paper aims to highlight the physical evolution of solutions from soaking and beans cooking process. This is motivated by the desire to shed light on the particular behavior of the bean end-of-cooking solutions when they are incorporated into the soil. For that purpose, solutions from soaking were produced by putting in contact 2kg of sorted and quickly washed beans seed with 8kg of water with known physical characteristics. Concerning the solutions from cooked beans, they were produced by putting on fire the pot containing the mixture of the water from soaking and bean seeds. The beans were a variety of Phaseolus vulgaris L.,known as “Meringue”. The cooking process was done without salts. The samples of solutions were collected as follow: 30 and 60 minutes respectively after the beginning of the soaking, 30, 60, and 90 minutes after the beginning of the cooking process of the beans soaked during 60 minutes. After each sampling, the equal volume of the solution collected was replaced with the water used for the cooking process. The color of the water used for the cooking process is translucent. Concerning solutions from soaking, their coloration are gradually reddish. Solutions from soaking and cooking process became abruptly dark red. From 60 minutes of the cooking process after soaking, the dark red coloration turn to strong brown. The solution handled in the case of the present study, from soaking and cooking the beans are gradually enriched in flakes compared to the situation noticed in the water used for the cooking process. But, the enrichment becomes abruptly high with the beginning of the cooking process after the process of soaking. In terms of consequence, their physical parameters studied in the present case study all increase in the same manner, notably the mass, the volumetric mass, and the density of the different solutions. The infiltration tests made including the water used for the different processes, solutions form the end of cooking the beans, and human urine show that the infiltration rate of the water from cooked beans is very low compared to that of the water used for the processes and human urine. The total infiltration of solution of the end of cooking the bean reveals on the infiltration surface the presence of a film of a matter bearing molds, generated by the progressive settling of this solution. The correlations established between the different parameters followed up here are highly positive. But in detail, the influence of an under laid parameter, known here as temperature, has been identified as being the responsible of the questioned behavior of the parameters taken in pairs in the case of correlation studies made. Finally, from this work, it emerges that the specific behavior of the bean end-of-cooking solution when it is introduced into the soil is justified by its progressive enrichment in organic matter during the cooking process.

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