Locally three-dimensional laminar flows

Bogolepov, V. V.; Lipatov, I. I.

doi:10.1007/bf00919619

Cited by 18 publications

(8 citation statements)

References 6 publications

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“…The resulting triple deck structure is rather novel in that it is a hybrid between the fully interactive and compensation regimes which seems to be somewhat different from what previously appeared in the literature (e.g. Bogolepov & Lipatov, 1985;Duck & Burggraf, 1986;Bogolepov, 1987;Bogolepov, 1988). Its numerical solution is discussed in subsection 4.2.…”

Section: Introductionmentioning

confidence: 76%

Nonlinear wakes behind a row of elongated roughness elements

et al. 2016

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This paper is concerned with the high Reynolds number flow over a spanwise periodic array of roughness elements with inter element spacing of the order of the local boundary layer thickness. While earlier work by Goldstein, Sescu, Duck and Choudhari (2010) and Goldstein, Sescu, Duck and Choudhari (2011) was mainly concerned with smaller roughness heights that produced relatively weak distortions of the downstream flow, the focus here is on extending the analysis to larger roughness heights and streamwise elongated planform shapes that together produce a qualitatively different, nonlinear behavior of the downstream wakes. The roughness scale flow now has a novel triple deck structure that is somewhat different from related studies that have previously appeared in the literature. The resulting flow is formally nonlinear in the intermediate wake region, where the streamwise distance is large compared to the roughness dimensions but small compared to the downstream distance from the leading edge, as well as in the far wake region where the streamwise length scale is of the order of the downstream distance from the leading edge. In contrast, the flow perturbations in both of these wake regions were strictly linear in the earlier work by Goldstein et al (2010Goldstein et al ( , 2011. This is an important difference because the nonlinear wake flow in the present case provides an appropriate basic state for studying the secondary instability and eventual breakdown into turbulence. _______________________________________________________________

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Section: Introductionmentioning

confidence: 76%

Nonlinear wakes behind a row of elongated roughness elements

et al. 2016

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“…The triple-deck asymptotic analysis [8][9][10][11][12] of perturbations in the vicinity of a three-dimensional hump revealed that the linearized boundary conditions are applicable only when the height of the hump is much smaller than the viscous sublayer thickness, i.e., hӶh cr = 5 L . For example, h cr / ␦ * is 0.13 and 0.11 in Refs.…”

Section: Discussionmentioning

confidence: 99%

“…Boundary-layer flows in the presence of threedimensional ͑3D͒ humps have been investigated extensively with the help of asymptotic methods [8][9][10][11][12] in the limit = R L −1/8 → 0, where R L is the Reynolds number based on the characteristic length of the oncoming boundary layer L and the freestream velocity U ϱ . The asymptotic methods are very helpful for an overall understanding of flow structure and for the purpose of deriving the governing parameters, whereas the quantitative results might be questionable at finite Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

Receptivity of a boundary-layer flow to a three-dimensional hump at finite Reynolds numbers

Tumin

Reshotko

2005

Physics of Fluids

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The receptivity of boundary-layer flow to a three-dimensional hump ͑an array of humps͒ at a finite Reynolds number is solved with the help of an expansion of the linearized solution of Navier-Stokes equations into the biorthogonal eigenfunction system. There are two counterrotating vortices behind the roughness element that bring the high-speed fluid down into the wake region. Depending on the geometry, two relatively high-speed streaks could be observed in the wake downstream from the hump. The results for the flow-field structure are in qualitative agreement with available computational data. The quantitative discrepancy is attributed to the nonlinear character of the receptivity mechanism at the parameters considered in the computational studies.

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“…Boundary-layer flows in the presence of three-dimensional (3D) humps have been investigated extensively with the help of asymptotic methods [SSB77,BL85,Bog86,Bog87,Bog88] in the limit e = RL 11 8 -+ 0, where RL is the Reynolds number based on the characteristic length of the oncoming boundary layer, L, and the freestream velocity, Uo. The asymptotic methods are very helpful for an overall understanding of flow structure and for the purpose of deriving the governing parameters, whereas the quantitative results might be questionable at finite Reynolds numbers.…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

Theoretical and Computational Studies of Stability, Transition and Flow Control in High-Speed Flows

Tumin¹

2011

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Public Reporting burden for this collection of information is estimated to average I hour per response. including the time for reviewing instructions, searching existing data sources. gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comment regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services. Directorate for information Operations and Reports. 1215 AFOSR /t0P(f North Randolph Street AFRL-SR-AR-TR-08-0144Suite 325, Room 3112 Arlington, VA 2299 3-1768 I1. SUPPLEMENTARY NOTESThe views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by other documentation. Approved for public release; distribution unlimited. ABSTRACT (Maximum 200 words)A comprehensive study of stability and receptivity of hypersonic boundary layers has been carried out. The main results of the project: 1. Mathematical method of the multimode decomposition for three-dimensional perturbations in compressible boundary layers has been developed. The method provides analysis of experimental and computational results for modes of discrete and continuous spectra. 2. Theory of boundary-layer receptivity was developed for roughness-induced perturbations in incompressible and compressible boundary layers. 3. The transient growth phenomenon in compressible boundary layers over flat plate, sphere, and sharp cone has been studied. The work was accompanied by development of solvers for these geometries. IntroductionThe potential of sustained hypersonic flight to revolutionize military and commercial activity is well recognized, and is reflected in recent initiatives such as the National Aerospace Initiative. High-speed vehicles will substantially impact military strategy by providing new defensive options such as a rapid on-demand global strike capability with much shorter response times than currently possible. Furthermore, the development of new technologies based on air-breathing propulsion can be leveraged to considerably reduce the cost of accessto-space, the benefits of which are both military as well as commercial. However, daunting technical challenges remain in realizing such vehicles. The harsh environment imposed by the envelope of such future missions is manifested in the severe anticipated thermo-mechanical loads and various propulsion-related requirements. Although the diversity of the physical phenomena encountered is broad, several key limiting issues have been identified as primary challenges, including both local and global constraints such as, for example, cowl lip loading and airframe balance. A scrutiny of the problems identified reveals the pervasive importance of several basic fluid dynamic phenomena. One of these, and possibly the least understood, is that of high-speed transition.The impact of hypersonic boundary lay...

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Locally three-dimensional laminar flows

Cited by 18 publications

References 6 publications

Nonlinear wakes behind a row of elongated roughness elements

Nonlinear wakes behind a row of elongated roughness elements

Receptivity of a boundary-layer flow to a three-dimensional hump at finite Reynolds numbers

Theoretical and Computational Studies of Stability, Transition and Flow Control in High-Speed Flows

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