3 edition of **On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation** found in the catalog.

On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation

- 254 Want to read
- 13 Currently reading

Published
**1990**
by National Aeronautics and Space Administration, Langley Research Center in Hampton, Va
.

Written in English

- Lagrange equations.,
- Unsteady flow (Fluid dynamics)

**Edition Notes**

Statement | Stephen J. Cowley, Leon L. Van Dommelen, Shui T. Lam. |

Series | ICASE report -- no. 90-47., NASA contractor report -- 182071., NASA contractor report -- NASA CR-182071. |

Contributions | Van Dommelen, Leon L., Lam, Shui T., Langley Research Center. |

The Physical Object | |
---|---|

Format | Microform |

Pagination | 1 v. |

ID Numbers | |

Open Library | OL15361217M |

Journal of Fluid Mechanics Additional services for Journal of Fluid Mechanics: Email alerts: Click here Subscriptions: Click here. Part of the Monte Verità book series (MV) Abstract. One of the major challenges in turbulence research has been to explain how the turbulence is created and to describe and analyze the space-time behavior of the turbulent eddies. S.T. On the use of Lagrangian variables in descriptions of unsteady boundary layer separation.

Boundary-layer separation can be prevented or delayed by sucking part of the boundary layer into the surface, but in a straightforward application the required hydraulics entail significant penalties in terms of weight and cost. On the Lagrangian Description of Unsteady Boundary-Layer Separation. Part 1. General Theory Book Proposal. In Lagrangian coordinates, a steady flow is also unsteady. Thus, it is possible to use one description for both steady and unsteady boundary layer separations. From equation (4) one can see that when a certain point in the flow field has the following properties x= 0, x =0 (5) then the integral along the x=x curve through this point is.

Euler vs Lagrange Consider smoke going up a chimney Euler approach Attach thermometer to the top of chimney, point 0. Record T as a function of time. As diﬀerent smoke particles pass through O, the temperature changes. Gives T(x0,y0,z0,t). More thermometers to get T(x,y,z,t). Lagrange approach Thermometers are attached to a particle, A. Velocity: Lagrangian and Eulerian Viewpoints There are two approaches to analyzing the velocity field: Lagrangian and Eulerian Lagrangian: keep track of individual fluids particles (i.e., solve F = Ma for each particle) Say particle p is at position r 1 (t 1) and at position r 2 (t 2) then, ̂ ̂ ̂ ̂ ̂ ̂.

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Downloaded from on Septem On the use of lagrangian variables in descriptions of unsteady boundary-layer separation By Stephen J. Cowley1!, Leon L. Van Dommelen2J and Shtji T. Lam3 1 Applied Mathematics. The lagrangian description of unsteady boundary-layer separation is reviewed from both analytical and numerical perspectives.

We explain in simple terms how particle distortion gives rise to unsteady separation, and why a theory centred on lagrangian coordinates provides the clearest description of this phenomenon.

On the Use of Lagrangian Variables in Descriptions of Unsteady Boundary-Layer Separation Article (PDF Available) in Philosophical Transactions of The Royal Society B. Get this from a library. On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation.

[Stephen J Cowley; Leon L Van Dommelen; Shui T Lam; Langley Research Center.]. The Lagrangian description of unsteady boundary layer separation is reviewed from both analytical and numerical perspectives.

It is explained in simple terms how particle distortion gives rise to unsteady separation, and why a theory centered on Lagrangian coordinates provides the clearest description of this phenomenon. Some of the more recent results for unsteady three Author: Stephen J.

Cowley, Leon L. Vandommelen, Shui T. Lam. On the Lagrangian description of unsteady boundary layer separation. Part 1: General theory On the Lagrangian Description.

the Lagrangian variables, although. y(t,t). The lagrangian description of unsteady boundary-layer separation is reviewed from both analytical and numerical perspectives.

We explain in simple terms how particle distortion gives rise to unsteady separation, and why a theory centred on lagrangian coordinates provides the clearest description of this phenomenon.

Included in the review are some of the more recent results for unsteady three. On the Lagrangian description of unsteady boundary-layer separation. Part 1. General theory. As far as unsteady separation is concerned, the advantage of a Lagrangian approach stems from the fact that in these coordinates the classical boundary-layer equations decouple into a momentum equation for the motion parallel to the boundary, and a continuity equation for the motion normal to the boundary (Shen ).

__' ON THE USE OF LAGRANGIAN VARIABLES IN DESCRIPTIONS OF UNSTEADY BOUNDARY-LAYER SEPARATION Stephen J. Cowley Leon L. Van Dommelen Shui T. Lam Contract No. NAS July Institute for Computer Applications in Science and Engineering D T IC NASA Langley Research Center-f, ELECTE Hampton, Virginia OCT03 The process of unsteady two-dimensional boundary-layer separation at high Reynolds number is considered.

Solutions of the unsteady non-interactive boundary-layer equations are known to develop a generic separation singularity in regions where the pressure gradient is prescribed and adverse.

The saddle points are detected through a Lagrangian approach as the location of maximum tangential rate of strain on Lagrangian coherent structures “ On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation,” Philos.

Trans. R “ Steady and unsteady boundary-layer separation,” Annu. Rev. Book Search tips Selecting this option will search all publications across the Scitation platform Selecting this option will search all publications for the Publisher/Society in context.

“ On the use of Lagrangian variables in descriptions of unsteady boundary-layer separation. For a periodic translation, the fixed separation is compared to the theory of Haller (J. Fluid Mech., vol.pp. –), while for non-periodic translations, a method is proposed to extract the moving separation point captured by a Lagrangian saddle point, and its finite-time unstable direction (separation profiles).

Intermediate. Abstract. The lagrangian description of unsteady boundary-layer separation is reviewed from\ud both analytical and numerical perspectives. We explain in simple terms how particle\ud distortion gives rise to unsteady separation, and why a theory centred on lagrangian\ud coordinates provides the clearest description of this phenomenon.

On the use of lagrangian variables in descriptions of unsteady boundary-layer separation BY STEPHEN J. COWLEY1t, LEON L. VAN DOMMELEN2t AND SHUI T. LAM3 1Applied MathematicsCalifornia Institute of Technology, Pasadena, CaliforniaU.S.A.

2Department of Mechanical Engineering, FAMU/FSU College of Engineering. The interaction between increased knowledge of unsteady separation processes and computational techniques is examined, emphasizing the use of Lagrangian coordinates.

Examples include boundary layer solutions of two dimensional unsteady flows, and separation from rotating and translating spheres. Abstract. The Lagrangian description of unsteady boundary layer separation is reviewed from both analytical and numerical perspectives.

It is explained in simple terms how particle distortion gives rise to unsteady separation, and why a theory centered on Lagrangian coordinates provides the clearest description of this phenomenon.

Extension of the familiar concept of boundary-layer separation to flow along moving walls and unsteady flows is a subject that attracted some interest in the ’s and has been investigated further in the past few years.

ON THE USE OF LAGRANGIAN VARIABLES IN DESCRIPTIONS OF UNSTEADY BOUNDARY-LAYER SEPARATION Stephen J. Cowley Leon L. Van Dommelen Shui T. Lam Contract No. NAS July Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton, Virginia Operated by the Universities Space Research Association.

Amir Faghri, Yuwen Zhang, in Transport Phenomena in Multiphase Systems, Lagrangian Averaging. Lagrangian averaging is directly related to the Lagrangian description of a system, which requires tracking the motion of each individual fluid particle.

Therefore, Lagrangian averaging is a very useful tool when the dynamics of individual particles are of interest.Extension of the familiar concept of boundary-layer separation to flow along moving walls and unsteady flows is a subject that attracted some interest in the ’s and has been investigated further in the past few years.

The well-known criterion of vanishing wall-shear does not apply in such flows, and therefore the definition of the phenomenon becomes more difficult than in the simpler.It includes the Lagrangian description of unsteady boundary-layer separation in three dimensions by Van Dommelen & Cowley and numerical calculation in an Eulerian framework performed by Wu & Shen and Affes et al.

in the context of the interaction of a tip-vortex with a cylinder simulating a helicopter airframe. They all found that a singularity.