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- Polynomial chaos expansions (2)
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Articles 1 - 14 of 14
Full-Text Articles in Aerospace Engineering
Coalescence Speed Of Two Equal-Sized Nanobubbles, Eric Bird, Jun Zhou, Zhi Liang
Coalescence Speed Of Two Equal-Sized Nanobubbles, Eric Bird, Jun Zhou, Zhi Liang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In This Work, We Use Molecular Dynamics (MD) Simulations Coupled with Continuum-Based Theoretical Analysis to Study the Coalescence Dynamics of Two Equal-Sized Nanobubbles (NBs). We First Derive a Governing Equation for the Evolution of the Capillary Bridge Radius between Two Coalescing NBs from the Axisymmetric Navier-Stokes Equation. to Verify the Prediction from the Governing Equation, We Carry Out MD Simulations of the Coalescence of Two NBs in a Lennard-Jones Fluid System and Directly Measure the Bridge Radius, Rb, as a Function of Time, T. by Varying the Bubble Diameter, We Change the NB Ohnesorge Number from 0.46 to 0.33. in …
Efficient Yield Estimation Of Multiband Patch Antennas By Polynomial Chaos-Based Kriging, Leifur Leifsson, Xiaosong Du, Slawomir Koziel
Efficient Yield Estimation Of Multiband Patch Antennas By Polynomial Chaos-Based Kriging, Leifur Leifsson, Xiaosong Du, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Yield estimation of antenna systems is important to check their robustness with respect to the uncertain sources. Since direct Monte Carlo sampling of accurate physics-based models can be computationally intensive, this work proposes the use of the polynomial chaos–Kriging (PC-Kriging) metamodeling method for fast yield estimation of multiband patch antennas. PC-Kriging integrates the polynomial chaos expansion (PCE) as the trend function of Kriging metamodel since the PCE is good at capturing the function tendency and Kriging is good at matching the observations at training points. The PC-Kriging method is demonstrated on two analytical cases and two multiband patch antenna cases …
Maximum Evaporating Flux Of Molecular Fluids From A Planar Liquid Surface, Eric Bird, Zhi Liang
Maximum Evaporating Flux Of Molecular Fluids From A Planar Liquid Surface, Eric Bird, Zhi Liang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In This Work, We Use the Kinetic Theory of Gases (KTG) to Develop a Theoretical Model to Understand the Role of Internal Motions of Molecules on the Maximum Evaporation Flux from a Planar Liquid Surface. the Kinetic Theory is Applied to Study the Evaporation of Molecular Fluids into a Vacuum and Predict the Dimensionless Maximum Evaporation Flux (JR,max, I.e., the Ratio of the Maximum Evaporation Flux to the Molar Flux Emitted from a Liquid Surface). the Key Assumptions Regarding the Velocity Distribution Function (VDF) of Polyatomic Molecules in the Highly Nonequilibrium Vapor Near the Evaporating Surface Are Validated by the …
Application Of Quantum-Markov Open System Models To Human Cognition And Decision, Jerome Busemeyer, Qizi Zhang, S. N. Balakrishnan, Zheng Wang
Application Of Quantum-Markov Open System Models To Human Cognition And Decision, Jerome Busemeyer, Qizi Zhang, S. N. Balakrishnan, Zheng Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Markov processes, such as random walk models, have been successfully used by cognitive and neural scientists to model human choice behavior and decision time for over 50 years. Recently, quantum walk models have been introduced as an alternative way to model the dynamics of human choice and confidence across time. Empirical evidence points to the need for both types of processes, and open system models provide a way to incorporate them both into a single process. However, some of the constraints required by open system models present challenges for achieving this goal. The purpose of this article is to address …
Thermal Transport Across The Interface Between Liquid N-Dodecane And Its Own Vapor: A Molecular Dynamics Study, Eric Bird, Jesus Gutierrez Plascencia, Zhi Liang
Thermal Transport Across The Interface Between Liquid N-Dodecane And Its Own Vapor: A Molecular Dynamics Study, Eric Bird, Jesus Gutierrez Plascencia, Zhi Liang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
There Are Two Possible Thermal Transport Mechanisms at Liquid-Gas Interfaces, Namely, Evaporation/condensation (I.e., Heat Transfer by Liquid-Vapor Phase Change at Liquid Surfaces) and Heat Conduction (I.e., Heat Exchange by Collisions between Gas Molecules and Liquid Surfaces). using Molecular Dynamics (MD) Simulations, We Study Thermal Transport Across the Liquid-Vapor Interface of a Model N-Dodecane (C12H26) under Various Driving Force Conditions. in Each MD Simulation, We Restrict the Thermal Energy to Be Transferred Across the Liquid-Vapor Interface by Only One Mechanism. in Spite of the Complex Intramolecular Interactions in N-Dodecane Molecules, Our Modeling Results Indicate that the Schrage Relationships, Which Were Shown …
A Molecular Dynamics Study Of Transient Evaporation And Condensation, Zhi Liang, Anirban Chandra, Eric Bird, Pawel Keblinski
A Molecular Dynamics Study Of Transient Evaporation And Condensation, Zhi Liang, Anirban Chandra, Eric Bird, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We Use Molecular Dynamics (MD) Simulations to Study the Transient Evaporation and Condensation of a Pure Fluid Ar in a Nanochannel. in the MD Model, the Evaporation and Condensation of Fluid Ar is Initiated by a Sudden Increase of the Temperature or Periodically Varying the Temperature in the Solid Substrate on One Side of the Nanochannel. in Both Cases, We Find the Transient Evaporation and Condensation Rates Obtained Directly from MD Simulations Are in Good Agreement with the Predictions from the Schrage Relationships. Furthermore, Our Analyses Show that the Kinetics of the Transient Heat and Mass Transfer between the Evaporating …
Multifidelity Modeling By Polynomial Chaos-Based Cokriging To Enable Efficient Model-Based Reliability Analysis Of Ndt Systems, Xiaosong Du, Leifur Leifsson
Multifidelity Modeling By Polynomial Chaos-Based Cokriging To Enable Efficient Model-Based Reliability Analysis Of Ndt Systems, Xiaosong Du, Leifur Leifsson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This work proposes a novel multifidelity metamodeling approach, the polynomial chaos-based Cokriging (PC-Cokriging). The proposed approach is used for fast uncertainty propagation in a reliability analysis of nondestructive testing systems using model-assisted probability of detection (MAPOD). In particular, PC-Cokriging is a multivariate version of polynomial chaos-based Kriging (PC-Kriging), which aims at combining the advantages of the regression-based polynomial chaos expansions and the interpolation-based Kriging metamodeling methods. Following a similar process as Cokriging, the PC-Cokriging advances PC-Kriging by enabling the incorporation of multifidelity physics information. The proposed PC-Cokriging is demonstrated on two analytical functions and three ultrasonic testing MAPOD cases. The …
Direct Numerical Simulations Of Acoustic Disturbances In Various Rectangular Nozzle Configurations, Nathaniel Hildebrand, Meelan M. Choudhari, Lian Duan
Direct Numerical Simulations Of Acoustic Disturbances In Various Rectangular Nozzle Configurations, Nathaniel Hildebrand, Meelan M. Choudhari, Lian Duan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We perform Direct Numerical Simulations (DNS) to study the acoustic freestream disturbances radiating from the turbulent boundary layers along the contoured nozzle walls of a hypersonic wind tunnel with a rectangular test section. To begin with, the effects of the spanwise end walls are suppressed by confining the spanwise computational domain to a finite segment of the overall nozzle cross section and by imposing periodic boundary conditions across that spanwise domain. Besides providing a building-block configuration to reveal partial effects of the enclosed acoustic environment within the wind tunnel, these computations serve as a steppingstone toward the goal of fully-3D …
Direct Numerical Simulation Of Turbulent Pressure Fluctuations Over A Cone At Mach 8, Junji Huang, Lian Duan, Katya M. Casper, Ross M. Wagnild, Neal P. Bitter
Direct Numerical Simulation Of Turbulent Pressure Fluctuations Over A Cone At Mach 8, Junji Huang, Lian Duan, Katya M. Casper, Ross M. Wagnild, Neal P. Bitter
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct numerical simulations (DNS) were conducted to characterize the pressure fluctuations under the turbulent portion of the boundary layer over a sharp 7◦ half-angle cone at a nominal freestream Mach number of 8 and a unit Reynolds number of Reunit = 13.4 x 106/m. The axisymmetric cone geometry and the flow conditions of the DNS matched those measured in the Sandia Hypersonic Wind Tunnel at Mach 8 (Sandia HWT-8). The DNS-predicted wall pressure statistics, including the root-mean-square (r.m.s.) fluctuations and the power spectral density (PSD), were compared with those measured in the Sandia HWT-8. A good comparison between the DNS …
Applications Of Polynomial Chaos-Based Cokriging To Aerodynamic Design Optimization Benchmark Problems, Jethro Nagawkar, Leifur Leifsson, Xiaosong Du
Applications Of Polynomial Chaos-Based Cokriging To Aerodynamic Design Optimization Benchmark Problems, Jethro Nagawkar, Leifur Leifsson, Xiaosong Du
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this work, the polynomial chaos-based Cokriging (PC-Cokriging) is applied to a benchmark aerodynamic design optimization problem. The aim is to perform fast design optimization using this multifidelity metamodel. Multifidelity metamodels use information at multiple levels of fidelity to make accurate and fast predictions. Higher amount of lower fidelity data can provide important information on the trends to a limited amount of high-fidelity (HF) data. The PC-Cokriging metamodel is a multivariate version of the polynomial chaos-based Kriging (PC-Kriging) metamodel and its construction is similar to Cokriging. It combines the advantages of the interpolation-based Kriging metamodel and the regression-based polynomial chaos …
Numerical Study Of Paramagnetic Elliptical Microparticles In Curved Channels And Uniform Magnetic Fields, Christopher Sobecki, Jie Zhang, Cheng Wang
Numerical Study Of Paramagnetic Elliptical Microparticles In Curved Channels And Uniform Magnetic Fields, Christopher Sobecki, Jie Zhang, Cheng Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We numerically investigated the dynamics of a paramagnetic elliptical particle immersed in a low Reynolds number Poiseuille flow in a curved channel and under a uniform magnetic field by direct numerical simulation. A finite element method, based on an arbitrary Lagrangian-Eulerian approach, analyzed how the channel geometry, the strength and direction of the magnetic field, and the particle shape affected the rotation and radial migration of the particle. The net radial migration of the particle was analyzed after executing a π rotation and at the exit of the curved channel with and without a magnetic field. In the absence of …
A Brief Review On 3d Bioprinted Skin Substitutes, Fateme Fayyazbakhsh, Ming-Chuan Leu
A Brief Review On 3d Bioprinted Skin Substitutes, Fateme Fayyazbakhsh, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Global Escalating Cases of Skin Donor Shortage for Patients with Severe Wounds Warn the Vital Need for Alternatives to Skin Allografts. over the Last Three Decades, Research in the Skin Regeneration Area Has Addressed the Unmet Need for Artificial Skin Substitutes. 3D Bioprinting is a Promising Innovative Technology to Accurately Fabricate Skin Constructs based on Natural or Synthetic Bioinks, Whether Loaded or Not Loaded with Native Skin Cells (I.e., Keratinocytes and Fibroblasts) or Stem Cells in the Prescribed 3D Hierarchal Structure to Create Artificial Multilayer and Single Cell-Laden Construct. in This Paper, the Recent Developments in 3D Bioprinting for …
A B-Spline-Based Generative Adversarial Network Model For Fast Interactive Airfoil Aerodynamic Optimization, Xiaosong Du, Ping He, Joaquim R.R.A. Martins
A B-Spline-Based Generative Adversarial Network Model For Fast Interactive Airfoil Aerodynamic Optimization, Xiaosong Du, Ping He, Joaquim R.R.A. Martins
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Airfoil aerodynamic optimization is of great importance in aircraft design; however, it relies on high-fidelity physics-based models that are computationally expensive to evaluate. In this work, we provide a methodology to reduce the computational cost for airfoil aerodynamic optimization. Firstly, we develop a B-spline based generative adversarial networks (BSplineGAN) parameterization method to automatically infer design space with sufficient shape variability. Secondly, we construct multi-layer neural network (MNN) surrogates for fast predictions on aerodynamic drag, lift, and pitching moment coefficients. The BSplineGAN has a relative error lower than 1% when fitting to UIUC database. Verification of MNN surrogates shows the root …
Simulation And Modeling Of Cold-Wall Hypersonic Turbulent Boundary Layers On Flat Plate, Junji Huang, Gary L. Nicholson, Lian Duan, Meelan M. Choudhari, Rodney D.W. Bowersox
Simulation And Modeling Of Cold-Wall Hypersonic Turbulent Boundary Layers On Flat Plate, Junji Huang, Gary L. Nicholson, Lian Duan, Meelan M. Choudhari, Rodney D.W. Bowersox
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct numerical simulations (DNS) of flat-plate, zero-pressure-gradient turbulent boundary layers are presented for nominal freestream Mach numbers of 11 and 14 and a highly cooled wall (wall-to-recovery temperature of approximately 0.2). The flow conditions of the DNS are representative of the experimental data for a Mach 11.1 turbulent boundary layer on a flat plate that was tested at Calspan–University of Buffalo Research Center (CUBRC) and the operational conditions of the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The wall shear stress and turbulent heat flux predicted by DNS show good comparisons with those measured at CUBRC and those modeled …