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Full-Text Articles in Aerodynamics and Fluid Mechanics

On The Selection Of A Good Shape Parameter For Rbf Approximation And Its Application For Solving Pdes, Lei-Hsin Kuo Aug 2015

On The Selection Of A Good Shape Parameter For Rbf Approximation And Its Application For Solving Pdes, Lei-Hsin Kuo

Dissertations

Meshless methods utilizing Radial Basis Functions~(RBFs) are a numerical method that require no mesh connections within the computational domain. They are useful for solving numerous real-world engineering problems. Over the past decades, after the 1970s, several RBFs have been developed and successfully applied to recover unknown functions and to solve Partial Differential Equations (PDEs).
However, some RBFs, such as Multiquadratic (MQ), Gaussian (GA), and Matern functions, contain a free variable, the shape parameter, c. Because c exerts a strong influence on the accuracy of numerical solutions, much effort has been devoted to developing methods for determining shape parameters which provide …


Computational Fluid Dynamics Study Of Balloon System Tethered To A Stratosail, Jayakanth Loganathan, Kian-Meng Lim, Heow Pueh Lee, Boo Cheong Khoo Jun 2015

Computational Fluid Dynamics Study Of Balloon System Tethered To A Stratosail, Jayakanth Loganathan, Kian-Meng Lim, Heow Pueh Lee, Boo Cheong Khoo

2017 Academic High Altitude Conference

In this paper, we present a numerical study of a stratospheric balloon system tethered to a passive device, known as the Stratosail, for station-keeping operation. For scientific applications, stratospheric balloons that operate at altitudes between 15 and 20 km will need to maintain station over a fixed point above the earth for a prescribed period of time. This is a challenging problem due to the limitation of payloads and lack of an energy source. The present study uses computational fluid dynamics (CFD) simulations to analyze the drift velocity of such a balloon-Stratosail system under typical wind conditions in the stratosphere. …


A Contribution Toward Better Understanding Of Overbanking Tendency In Fixed-Wing Aircraft, Nihad E. Daidzic Feb 2015

A Contribution Toward Better Understanding Of Overbanking Tendency In Fixed-Wing Aircraft, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

The phenomenon of overbanking tendency for a rigid-body, fixed-wing aircraft is investigated. Overbanking tendency is defined as a spontaneous, unbalanced rolling moment that keeps increasing an airplane’s bank angle in steep turns and must be arrested by opposite aileron action. As stated by the Federal Aviation Administration, the overbanking tendency may lead to a loss of control, especially in instrument meteorological conditions. It was found in this study that the speed differential over wing halves in horizontal turns indeed creates a rolling moment that achieves maximum values for bank angles between 45 and 55 degrees. However, this induced rolling moment …


High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang Jan 2015

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …