Comparison of the Triple-Deck Theory, Interactive Boundary Layer Method, and Navier-Stokes Computation for Marginal Separation

1994 ◽  
Vol 116 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Chao-Tsung Hsiao ◽  
Laura L. Pauley
Keyword(s):  
Boundary Layer ◽  
Separation Bubble ◽  
Physical Phenomenon ◽  
Navier Stokes ◽  
Gradient Distribution ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Incompressible Boundary ◽  
Layer Flow ◽  
Comparison Of The Results

The steady two-dimensional marginal separation of an incompressible boundary layer flow within a channel was solved independently by three different methods: the triple-deck method of marginal separation, the interactive boundary layer method, and the full Navier-Stokes computation. From comparison of the results between these three methods, the accuracy and appropriateness of each method was determined. The critical condition beyond which the steady marginal separation solution of triple-deck method does not exist was related to a physical phenomenon in which the separation bubble becomes unsteady. Factors such as Reynolds number and pressure gradient distribution which might influence the accuracy of the marginal separation solution were also investigated.

Compressible Conical Diffuser Flow Using the Energy Deficit Boundary Layer Method

1975 ◽  
Vol 17 (4) ◽  
pp. 206-213
Author(s):  
J. L. Livesey ◽  
A. O. Odukwe ◽  
W. A. Kamal
Keyword(s):  
Boundary Layer ◽  
Performance Prediction ◽  
Prediction Method ◽  
Energy Deficit ◽  
Layer Method ◽  
Diffuser Flow ◽  
Conical Diffuser ◽  
Boundary Layer Method ◽  
Incompressible Boundary ◽  
Good Agreement

A performance prediction method for high inlet Mach number conical diffusers is developed, which uses the kinetic energy deficit equation in the calculation of the compressible turbulent boundary layer. A power law velocity profile is assumed together with Crocco's relation for the temperature distribution. Following Green, Morkovin's hypothesis is invoked to extend to the compressible flow the existing relations for the shear work integral originally developed for incompressible boundary layers. Comparison of the predicted results with available experimental results shows good agreement.

A “Boundary Layer” Method of Obtaining an Approximate Solution to the Infinite Fin Problem

2002 ◽  
Author(s):  
William S. Janna ◽  
John I. Hochstein
Keyword(s):  
Boundary Layer ◽  
Exact Solution ◽  
Approximate Solutions ◽  
Third Order ◽  
Fin Efficiency ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Layer Flow ◽  
Alternative Solutions ◽  
Good Agreement

The classical infinite fin problem is considered in this study. First the exact solution is stated in which temperature, heat transfer rate, effectiveness and fin efficiency are all given. Then the boundary layer method is used to obtain alternative solutions in polynomial form. Boundary conditions are written for this method, and applied in various combinations to an assumed temperature profile. First, second, and third order approximate solutions are derived. Temperature profiles obtained from these solutions are compared to that calculated from the exact solution. It is shown that as more terms are included in the assumed profile, the resultant expression better fits the exact solution. Very good agreement between the third order and exact solution was obtained. Also derived from the approximate solutions was a distance along the fin beyond which the temperature difference between the fin and the surroundings is negligible. This arbitrary distance is analogous to the boundary layer thickness for boundary layer flow over a flat plate.

Development of a Wing Section Design Code Including Inviscid/Viscous Interaction

2012 ◽  
Author(s):  
Christoph Michael Steinbach ◽  
Stefan Krueger
Keyword(s):  
Boundary Layer ◽  
Turbulent Flows ◽  
Inviscid Flow ◽  
Momentum Equation ◽  
Navier Stokes ◽  
Computational Time ◽  
Wing Section ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Section Design

For wing design purposes the value of maximum lift angle is an important quantity. At the high Reynolds Numbers in naval architecture flows the onset and development of turbulent separation is the deciding value for the maximum lift angle. For the calculation of separated turbulent flows usually fully viscous flow solvers, like e.g. Reynolds averaged Navier Stokes (RANS) Solvers, are used. Instead of this kind of solvers, which are expensive by means of computational time, also interacting boundary layer (IBL) methods can be used. Due to the viscous-inviscid coupling, these methods are able to compute flows with limited separation up to the maximum lift angle and represent a cheap and robust alternative to higher value viscous solvers. In this paper a turbulent boundary layer method solving the integral momentum equation together with the integral energy equation of the boundary layer in an inverse formulation is described. The method is combined with an existing inviscid flow solver for 2D wing section flows and a laminar boundary layer method code including transition forecast.

Boundary layer method in the problem of far propagation of surface SV-waves

2011 ◽  
Vol 175 (6) ◽  
pp. 651-671
Author(s):  
N. Ya. Kirpichnikova ◽  
A. S. Kirpichnikova
Keyword(s):  
Boundary Layer ◽  
Layer Method ◽  
Boundary Layer Method

A Simple and Robust Subsonic Boundary Layer Method to Be Used with the Panel Method for Wing Calculations Using a Wing Strip Approach

2015 ◽  
Vol 798 ◽  
pp. 596-601
Author(s):  
R.F. Francisco Reis ◽  
Guilherme A. Santana ◽  
Paulo Iscold ◽  
Carlos A. Cimini
Keyword(s):  
Boundary Layer ◽  
Lift Coefficient ◽  
Aircraft Design ◽  
Aerodynamic Characteristics ◽  
Viscous Drag ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Classical Integral ◽  
Empirical Corrections

This paper will present the development of a simple subsonic boundary layer method suitable to be used coupled with panel methods in order to estimate the aerodynamic characteristics, including viscous drag and maximum lift coefficient, of 3D wings. The proposed method does not require viscous-inviscid iterations and is based on classical integral bi-dimensional boundary layer theory using Thwaites and Head ́s models with bi-dimensional empirical corrections applied to each wing strip being therefor robust and efficient to be used in the early conceptual stage of aircraft design. Presented results are compared to the Modified CS Method in an IBL scheme and experimental data and are shown to provide good results.

Optimal growth, model reduction and control in a separated boundary-layer flow using global eigenmodes

2007 ◽  
Vol 579 ◽  
pp. 305-314 ◽  
Author(s):  
ESPEN ÅKERVIK ◽  
JÉRÔME HŒPFFNER ◽  
UWE EHRENSTEIN ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Separation Bubble ◽  
Flow Simulation ◽  
Optimal Growth ◽  
Reduced Model ◽  
Linear Quadratic ◽  
Reduced Basis ◽  
Worst Case ◽  
Layer Flow

Two-dimensional global eigenmodes are used as a projection basis both for analysing the dynamics and building a reduced model for control in a prototype separated boundary-layer flow. In the present configuration, a high-aspect-ratio smooth cavity-like geometry confines the separation bubble. Optimal growth analysis using the reduced basis shows that the sum of the highly non-normal global eigenmodes is able to describe a localized disturbance. Subject to this worst-case initial condition, a large transient growth associated with the development of a wavepacket along the shear layer followed by a global cycle related to the two unstable global eigenmodes is found. The flow simulation procedure is coupled to a measurement feedback controller, which senses the wall shear stress at the downstream lip of the cavity and actuates at the upstream lip. A reduced model for the control optimization is obtained by a projection on the least stable global eigenmodes, and the resulting linear-quadratic-Gaussian controller is applied to the Navier–Stokes time integration. It is shown that the controller is able to damp out the global oscillations.

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