Second-order, far-field computational boundary conditions for inviscid duct flow problems

AIAA Journal ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 1268-1276 ◽  
Author(s):  
A. Verhoff ◽  
D. Stookesberry
Keyword(s):  
Boundary Conditions ◽  
Second Order ◽  
Far Field ◽  
Duct Flow ◽  
Flow Problems

Linearized no-slip boundary conditions at a rough surface

2013 ◽  
Vol 737 ◽  
pp. 349-367 ◽  
Author(s):  
Paolo Luchini
Keyword(s):  
Aspect Ratio ◽  
Boundary Conditions ◽  
Solid Wall ◽  
Stokes Problem ◽  
Far Field ◽  
Slip Boundary Conditions ◽  
Transition Prediction ◽  
Slip Boundary ◽  
Flow Problems ◽  
Field Behaviour

AbstractLinearized boundary conditions are a commonplace numerical tool in any flow problems where the solid wall is nominally flat but the effects of small waviness or roughness are being investigated. Typical examples are stability problems in the presence of undulated walls or interfaces, and receptivity problems in aerodynamic transition prediction or turbulent flow control. However, to pose such problems properly, solutions in two mathematical distinguished limits have to be considered: a shallow-roughness limit, where not only roughness height but also its aspect ratio becomes smaller and smaller, and a small-roughness limit, where the size of the roughness tends to zero but its aspect ratio need not. Here a connection between the two solutions is established through an analysis of their far-field behaviour. As a result, the effect of the surface in the small-roughness limit, obtained from a numerical solution of the Stokes problem, can be recast as an equivalent shallow-roughness linearized boundary condition corrected by a suitable protrusion coefficient (related to the protrusion height used years ago in the study of riblets) and a proximity coefficient, accounting for the interference between multiple protrusions in a periodic array. Numerically computed plots and interpolation formulas of such correction coefficients are provided.

Far-field computational boundary conditions for two-dimensional external flow problems

AIAA Journal ◽  
1992 ◽  
Vol 30 (11) ◽  
pp. 2585-2594 ◽  
Author(s):  
A. Verhoff ◽  
D. Stookesberry ◽  
S. Agrawal
Keyword(s):  
Boundary Conditions ◽  
External Flow ◽  
Far Field ◽  
Two Dimensional ◽  
Flow Problems

scholarly journals Computational Actuator Disc Models for Wind and Tidal Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
B. Johnson ◽  
J. Francis ◽  
J. Howe ◽  
J. Whitty
Keyword(s):  
Boundary Conditions ◽  
Channel Flow ◽  
Fluid Dynamic ◽  
Experimental Studies ◽  
Resistance Coefficient ◽  
Momentum Equation ◽  
Far Field ◽  
Duct Flow ◽  
Thrust Coefficient ◽  
Actuator Disc

This paper details a computational fluid dynamic (CFD) study of a constantly loaded actuator disc model featuring different boundary conditions; these boundary conditions were defined to represent a channel and a duct flow. The simulations were carried out using the commercially available CFD software ANSYS-CFX. The data produced were compared to the one-dimensional (1D) momentum equation as well as previous numerical and experimental studies featuring porous discs in a channel flow. The actuator disc was modelled as a momentum loss using a resistance coefficient related to the thrust coefficient (CT). The model showed good agreement with the 1D momentum theory in terms of the velocity and pressure profiles. Less agreement was demonstrated when compared to previous numerical and empirical data in terms of velocity and turbulence characteristics in the far field. These models predicted a far larger velocity deficit and a turbulence peak further downstream. This study therefore demonstrates the usefulness of the duct boundary condition (for computational ease) for representing open channel flow when simulating far field effects as well as the importance of turbulence definition at the inlet.

Sign in / Sign up

Export Citation Format

Share Document