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Aerospace Engineering Commons

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Articles 1 - 7 of 7

Full-Text Articles in Aerospace Engineering

Effects Of Magnetic Fields On Magnetohydrodynamic Cylindrical And Spherical Richtmyer-Meshkov Instability, Wouter Mostert, Vincent Wheatley, Ravi Samtaney, Dale I. Pullin Oct 2015

Effects Of Magnetic Fields On Magnetohydrodynamic Cylindrical And Spherical Richtmyer-Meshkov Instability, Wouter Mostert, Vincent Wheatley, Ravi Samtaney, Dale I. Pullin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The effects of seed magnetic fields on the Richtmyer-Meshkov instability driven by converging cylindrical and spherical implosions in ideal magnetohydrodynamics are investigated. Two different seed field configurations at various strengths are applied over a cylindrical or spherical density interface which has a single-dominant-mode perturbation. The shocks that excite the instability are generated with appropriate Riemann problems in a numerical formulation and the effect of the seed field on the growth rate and symmetry of the perturbations on the density interface is examined. We find reduced perturbation growth for both field configurations and all tested strengths. The extent of growth suppression …


Coalescence-Induced Jumping Of Nanoscale Droplets On Super-Hydrophobic Surfaces, Zhi Liang, Pawel Keblinski Oct 2015

Coalescence-Induced Jumping Of Nanoscale Droplets On Super-Hydrophobic Surfaces, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Coalescence-Induced Jumping of Tens of Microns Size Droplets on Super-Hydrophobic Surfaces Has Been Observed in Both Experiments and Simulations. However, Whether the Coalescence-Induced Jumping Would Occur for Smaller, Particularly Nanoscale Droplets, is an Open Question. using Molecular Dynamics Simulations, We Demonstrate that in Spite of the Large Internal Viscous Dissipation, Coalescence of Two Nanoscale Droplets on a Super-Hydrophobic Surface Can Result in a Jumping of the Coalesced Droplet from the Surface with a Speed of a Few M/s. Similar to the Coalescence-Induced Jumping of Microscale Droplets, We Observe that the Bridge between the Coalescing Nano-Droplets Expands and Impacts the …


Molecular Simulations And Lattice Dynamics Determination Of Stillinger-Weber Gan Thermal Conductivity, Zhi Liang, Ankit Jain, Alan J.H. Mcgaughey, Pawel Keblinski Sep 2015

Molecular Simulations And Lattice Dynamics Determination Of Stillinger-Weber Gan Thermal Conductivity, Zhi Liang, Ankit Jain, Alan J.H. Mcgaughey, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Bulk Thermal Conductivity of Stillinger-Weber (SW) Wurtzite GaN in the [0001] Direction at a Temperature of 300 K is Calculated using Equilibrium Molecular Dynamics (EMD), Non-Equilibrium MD (NEMD), and Lattice Dynamics (LD) Methods. While the NEMD Method Predicts a Thermal Conductivity of 166 ± 11 W/m·K, Both the EMD and LD Methods Predict Thermal Conductivities that Are an Order of Magnitude Greater. We Attribute the Discrepancy to Significant Contributions to Thermal Conductivity from Long-Mean Free Path Phonons. We Propose that the Grüneisen Parameter for Low-Frequency Phonons is a Good Predictor of the Severity of the Size Effects in NEMD …


Experimental Investigations Of Dusty Spacecraft Charging At The Lunar Terminator, Kevin Chou, William Yu, Daoru Frank Han, Joseph J. Wang Sep 2015

Experimental Investigations Of Dusty Spacecraft Charging At The Lunar Terminator, Kevin Chou, William Yu, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An experimental investigation is conducted to understand the I-V characteristics and floating potential of a surface covered by varying amounts of dust in a plasma environment similar to that at the lunar terminator. I-V curves are measured to determine dust coverage effects on surface charging, and a non-contacting electrostatic voltmeter is used to measure dust surface charging. Results show that as dust coverage increases, the electric field created between the dust surface layer and conducting surface layer increases the possibility of arcing and breakdown.


Slip Length Crossover On A Graphene Surface, Zhi Liang, Pawel Keblinski Apr 2015

Slip Length Crossover On A Graphene Surface, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Equilibrium and Non-Equilibrium Molecular Dynamics Simulations, We Study the Flow of Argon Fluid above the Critical Temperature in a Planar Nanochannel Delimited by Graphene Walls. We Observe that, as a Function of Pressure, the Slip Length First Decreases Due to the Decreasing Mean Free Path of Gas Molecules, Reaches the Minimum Value When the Pressure is Close to the Critical Pressure, and Then Increases with Further Increase in Pressure. We Demonstrate that the Slip Length Increase at High Pressures is Due to the Fact that the Viscosity of Fluid Increases Much Faster with Pressure Than the Friction Coefficient between …


An Interoperable System For Automated Diagnosis Of Cardiac Abnormalities From Electrocardiogram Data, Thidarat Tinnakornsrisuphap, Richard E. Billo Mar 2015

An Interoperable System For Automated Diagnosis Of Cardiac Abnormalities From Electrocardiogram Data, Thidarat Tinnakornsrisuphap, Richard E. Billo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electrocardiogram (ECG) data are stored and analyzed in different formats, devices, and computer platforms. As a result, ECG data from different monitoring devices cannot be displayed unless the user has access to the proprietary software of each particular device. This research describes an ontology and encoding for representation of ECG data that allows open exchange and display of ECG data in a web browser. The ontology is based on the Health Level Seven (HL7) medical device communication standard. It integrates ECG waveform data, HL7 standard ECG data descriptions, and cardiac diagnosis rules, providing a capability to both represent ECG waveforms …


Numerical Simulations Of Surface Charging At The Lunar Terminator, Daoru Frank Han, Joseph J. Wang Jan 2015

Numerical Simulations Of Surface Charging At The Lunar Terminator, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A full-particle particle-in-cell (PIC) simulation model is developed to perform fully-kinetic simulations of surface-plasma interactions at the lunar terminator region. This model uses a non-homogeneous immersed-finite-element (IFE) solver to calculate the electric field discontinuity (flux jump) at the plasma-surface interface and surface charging for realistic lunar surface terrain. The simulation includes all plasma species, including the solar wind electrons and ions, as well as photoelectrons with real proton-to-electron mass ratio so the kinetic properties in the mesothermal flow are resolved. We present simulation results of surface charging around a lunar hill at the lunar terminator region.