Viscid-Inviscid Interaction of Incompressible Separated Flows

1976 ◽  
Vol 43 (3) ◽  
pp. 387-395 ◽  
Author(s):  
W. L. Chow ◽  
D. J. Spring
Keyword(s):  
Viscous Flow ◽  
Pressure Coefficient ◽  
Separated Flow ◽  
Inviscid Flow ◽  
Turbulent Jet ◽  
Tunnel Wall ◽  
Flow Process ◽  
Jet Mixing ◽  
Flow Problems ◽  
Flow Components

A flow model has been devised to deal with the viscid-inviscid interaction of a class of two-dimensional incompressible separated flow problems. It is suggested that the corresponding inviscid flow of these problems is described by the free streamline theory with few unspecified parameters and their values are, in turn, determined by the viscous flow considerations. The problem of a flow past a backward facing step is selected for study in detail. The viscous flow components of turbulent jet mixing, recompression, and reattachment are delineated and studied individually. When they are later combined, it is found that the point of reattachment behaves as a saddle-point-type singularity in the system of differential equations describing the viscous flow process. This feature is employed to the determination of the aforementioned free parameters and thus the establishment of the overall corresponding inviscid flow field. The resulting base pressure coefficient for the specific case agrees reasonably well with the available experimental data. Additional calculations are performed to demonstrate the influence of higher Reynolds numbers and the values of the similarity (or spread rate) parameter σ of the “constant pressure” turbulent jet mixing process. Further studies of redevelopment of the viscous flow after reattachment, the turbulent exchange within the recompression and redevelopment regions, and the effect of wind tunnel-wall interference on the overall flow patterns have been suggested and discussed.

The steady separated flow past a circular cylinder at large Reynolds numbers

1965 ◽  
Vol 21 (4) ◽  
pp. 737-760 ◽  
Author(s):  
Andreas Acrivos ◽  
D. D. Snowden ◽  
A. S. Grove ◽  
E. E. Petersen
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Pressure Coefficient ◽  
Separated Flow ◽  
Inviscid Flow ◽  
Cylinder Surface ◽  
Finite Width ◽  
Viscous Effects ◽  
Flow Past ◽  
Order Of Magnitude

This paper is concerned with deducing the most important features of the steady separated flow past a circular cylinder in the limit of vanishing viscosity. First of all, it is shown that the experimental results reported in an earlier article cannot be reconciled with the notion that, as the Reynolds number Re is increased, the flow becomes inviscid everywhere and that viscous effects remain confined within infinitesimally thin shear layers. In contrast, the limiting solution is visualized as exhibiting three essential features: a viscous, closed ‘wake bubble’ of finite width but with a length increasing linearly with Re in which inertial and viscous effects are everywhere of equal order of magnitude; an outer inviscid flow; and, separating the two regions, a diffuse viscous layer covering large sections of the external field. Further properties of this asymptotic solution include: a finite form drag, a negative rear pressure coefficient at the rear stagnation point of the cylinder, and a Nusselt number for heat transfer which becomes independent of Re along the non-wetted portion of the cylinder surface. This model is shown to be consistent with all the experimental data presently available, including some new heat transfer results that are presented in this paper.An approximate technique is also proposed which takes into account the asymptotic character of the flow in the vicinity of the cylinder and which predicts the pressure distribution around the cylinder in good agreement with the experiments.

Simultaneous Velocity and Concentration Measurements of a Turbulent Jet Mixing Flow

2002 ◽  
Vol 972 (1) ◽  
pp. 254-259 ◽  
Author(s):  
HUI HU ◽  
TETSUO SAGA ◽  
TOSHIO KOBAYASHI ◽  
NOBUYUKI TANIGUCHI
Keyword(s):  
Turbulent Jet ◽  
Jet Mixing ◽  
Concentration Measurements

scholarly journals Skeleton-stabilized immersogeometric analysis for incompressible viscous flow problems

2019 ◽  
Vol 344 ◽  
pp. 421-450 ◽  
Author(s):  
Tuong Hoang ◽  
Clemens V. Verhoosel ◽  
Chao-Zhong Qin ◽  
Ferdinando Auricchio ◽  
Alessandro Reali ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Flow Problems ◽  
Incompressible Viscous Flow

scholarly journals Computation of Secondary Flows in an Axial Flow Compressor Including Inviscid and Viscous Flow Computation

1984 ◽  
Author(s):  
Francis Leboeuf
Keyword(s):  
Boundary Layer ◽  
Viscous Flow ◽  
Axial Flow ◽  
Inviscid Flow ◽  
Secondary Flows ◽  
Computational Method ◽  
Flow Computation ◽  
Axial Flow Compressor ◽  
Flow Compressor ◽  
Highly Loaded

A computational method for secondary flows in a compressor has been extended to treat stalled flows. An integral equation is used which simulates the inviscid flow at the wall, under the viscous flow influence. We present comparisons with experimental results for a 2D stalled boundary layer, and for the secondary flow in a highly loaded stator of an axial flow compressor.

Boson Hamiltonians and stochasticity for the vorticity equation

1990 ◽  
Vol 68 (9) ◽  
pp. 719-722 ◽  
Author(s):  
Hubert H. Shen
Keyword(s):  
Viscous Flow ◽  
Inviscid Flow ◽  
Vorticity Equation ◽  
Hamiltonian Form ◽  
Bose Operators

The evolution of the vorticity in time for 2D inviscid flow and in Lagrangian time for 3D viscous flow is written in Hamiltonian form by introducing Bose operators. The addition of the viscous and convective terms, respectively, leads to an interpretation of the Hamiltonian contribution to the evolution as Langevin noise.

Numerical Investigation of Blade Flutter at or Near Stall in Axial Flow Turbomachines

2001 ◽  
Author(s):  
Wolfgang Höhn
Keyword(s):  
Viscous Flow ◽  
Stokes Equations ◽  
Separated Flow ◽  
Parallel Computer ◽  
Navier Stokes ◽  
Computational Domain ◽  
Compressor Cascade ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Blade Flutter

During the design of the compressor and turbine stages of today’s aeroengines, aerodynamically induced vibrations become increasingly important since higher blade load and better efficiency are desired. In this paper the development of a method based on the unsteady, compressible Navier-Stokes equations in two dimensions is described in order to study the physics of flutter for unsteady viscous flow around cascaded vibrating blades at stall. The governing equations are solved by a finite difference technique in boundary fitted coordinates. The numerical scheme uses the Advection Upstream Splitting Method to discretize the convective terms and central differences discretizing the viscous terms of the fully non-linear Navier-Stokes equations on a moving H-type mesh. The unsteady governing equations are explicitly and implicitly marched in time in a time-accurate way using a four stage Runge-Kutta scheme on a parallel computer or an implicit scheme of the Beam-Warming type on a single processor. Turbulence is modelled using the Baldwin-Lomax turbulence model. The blade flutter phenomenon is simulated by imposing a harmonic motion on the blade, which consists of harmonic body translation in two directions and a rotation, allowing an interblade phase angle between neighboring blades. Non-reflecting boundary conditions are used for the unsteady analysis at inlet and outlet of the computational domain. The computations are performed on multiple blade passages in order to account for nonlinear effects. A subsonic massively stalled unsteady flow case in a compressor cascade is studied. The results, compared with experiments and the predictions of other researchers, show reasonable agreement for inviscid and viscous flow cases for the investigated flow situations with respect to the Steady and unsteady pressure distribution on the blade in separated flow areas as well as the aeroelastic damping. The results show the applicability of the scheme for stalled flow around cascaded blades. As expected the viscous and inviscid computations show different results in regions where viscous effects are important, i.e. in separated flow areas. In particular, different predictions for inviscid and viscous flow for the aerodynamic damping for the investigated flow cases are found.

Status of Centrifugal Impeller Internal Aerodynamics—Part II: Experiments and Influence of Viscosity

1980 ◽  
Vol 102 (3) ◽  
pp. 738-746 ◽  
Author(s):  
D. Adler
Keyword(s):  
Viscous Flow ◽  
Experimental Work ◽  
State Of The Art ◽  
Centrifugal Impeller ◽  
Future Research ◽  
Research Topics ◽  
Flow Problems ◽  
Recent Developments ◽  
Internal Aerodynamics ◽  
The Subject

Recent developments in internal viscous aerodynamics of centrifugal impellers and related flows are critically reviewed. The overall picture which emerges provides the reader with a state-of-the-art perspective on the subject. Gaps in understanding are identified to stimulate future research. Topics included in this review are: experimental work carried out in the last decade, the structure of turbulence in curved rotating passages and solution of viscous flow problems in impellers.

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