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Numerical studies on receptivity and...

Whang, Chong Wook.

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Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers./
Author:	Whang, Chong Wook.
Description:	163 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2887.
Contained By:	Dissertation Abstracts International64-06B.
Subject:	Engineering, Mechanical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3094207
ISBN:	0496419080

Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers.
Whang, Chong Wook.

Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers. - 163 p.

Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2887.

Thesis (Ph.D.)--University of California, Los Angeles, 2003.

The transition of hypersonic boundary layer flow is one of the fundamental problems in fluid mechanics, and Gortler instability is one of many boundary layer instability mechanisms. The study of the Gortler vortices and their role in laminar-turbulent transition of hypersonic boundary layers has practical significance because many engineering designs, such as hypersonic engine inlets, involve concave surfaces. In general, Gortler vortices become turbulent in four steps: (1) the receptivity of disturbances, (2) the linear growth of the spanwise disturbances, (3) the nonlinear development of the vortices, and (4) the secondary instabilities. Although there have been extensive studies on the Gortler instabilities in incompressible flow, there are only a few studies in hypersonic flows based on LST (linear stability theory) or asymptotic studies only.

ISBN: 0496419080Subjects--Topical Terms:

783786
Engineering, Mechanical.

Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers.
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035 $a (UnM)AAI3094207
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100 1 $a Whang, Chong Wook. $3 1939708
245 1 0 $a Numerical studies on receptivity and transition of Gortler instabilities in hypersonic boundary layers.
300 $a 163 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2887.
500 $a Chair: Xiaolin Zhong.
502 $a Thesis (Ph.D.)--University of California, Los Angeles, 2003.
520 $a The transition of hypersonic boundary layer flow is one of the fundamental problems in fluid mechanics, and Gortler instability is one of many boundary layer instability mechanisms. The study of the Gortler vortices and their role in laminar-turbulent transition of hypersonic boundary layers has practical significance because many engineering designs, such as hypersonic engine inlets, involve concave surfaces. In general, Gortler vortices become turbulent in four steps: (1) the receptivity of disturbances, (2) the linear growth of the spanwise disturbances, (3) the nonlinear development of the vortices, and (4) the secondary instabilities. Although there have been extensive studies on the Gortler instabilities in incompressible flow, there are only a few studies in hypersonic flows based on LST (linear stability theory) or asymptotic studies only.
520 $a In this research, linear and nonlinear development and receptivity of the hypersonic Gortler vortices are studied using both the spatial DNS (direct numerical simulation) and LST approaches. At the same time, the properties of the Gortler are also analyzed by linear stability analysis and are compared with the DNS results. Specifically, Gortler vortices in a Mach 15 flow over a blunt wedge with a concave surface are investigated by solving the full Navier-Stokes equations in a spatially developing computational domain bounded by the bow shock wave and the solid wall.
520 $a It is found that DNS results of linear development of hypersonic Gortler vortices agree well with those from LST which shows that the linear region of hypersonic Gortler vortices can be predicted by LST analysis. The DNS results of the nonlinear development of the hypersonic Gortler vortices show the overall results of the nonlinear development of Gorlter instability at hypersonic flow are similar to those in incompressible flow, with the exception that higher harmonic modes as well as the fundamental change significantly compared to the linear solution. Leading edge receptivity to free stream standing vorticity waves shows that there are two growing mechanisms inside hypersonic boundary layers induced by the vorticity waves which are the early spatial transient growth near the leading edge due to the coupling of non-orthogonal eigenvectors and Gorlter instability in concave region. While the early transient growth is due to the superposition of different non-orthogonal modes, Gorlter instability is the growth of a single mode. However, it is found that these mechanisms have the similar characteristics which implies the growing mechanism due to the early transient is closely related with the one in Gortler instability. It may be because two different growing mechanisms are originated from the same lift-up effects of counter rotating vortices.
590 $a School code: 0031.
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Engineering, Aerospace. $3 1018395
650 4 $a Applied Mechanics. $3 1018410
690 $a 0548
690 $a 0538
690 $a 0346
710 2 0 $a University of California, Los Angeles. $3 626622
773 0 $t Dissertation Abstracts International $g 64-06B.
790 1 0 $a Zhong, Xiaolin, $e advisor
790 $a 0031
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3094207