scholarly journals A new form of the elliptic relaxation equation to account for wall effects in RANS modeling

2000 ◽  
Vol 12 (9) ◽  
pp. 2345-2351 ◽  
Author(s):  
Rémi Manceau ◽  
Kemal Hanjalić
Keyword(s):  
Wall Effects ◽  
Relaxation Equation ◽  
Elliptic Relaxation ◽  
Rans Modeling ◽  
New Form

Modeling near-wall effects in axially rotating pipe flow by elliptic relaxation

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1164-1170
Author(s):  
B. A. Pettersson ◽  
H. I. Andersson ◽  
A. S. Brunvoll
Keyword(s):  
Pipe Flow ◽  
Wall Effects ◽  
Elliptic Relaxation ◽  
Rotating Pipe Flow ◽  
Near Wall

Modeling near-wall effects in second-moment closures by elliptic relaxation

1996 ◽  
Vol 17 (3) ◽  
pp. 255-266 ◽  
Author(s):  
V. Wizman ◽  
D. Laurence ◽  
M. Kanniche ◽  
P. Durbin ◽  
A. Demuren
Keyword(s):  
Wall Effects ◽  
Second Moment ◽  
Moment Closures ◽  
Elliptic Relaxation ◽  
Near Wall

scholarly journals Inhomogeneity and anisotropy effects on the redistribution term in Reynolds-averaged Navier–Stokes modelling

2001 ◽  
Vol 438 ◽  
pp. 307-338 ◽  
Author(s):  
RÉMI MANCEAU ◽  
MENG WANG ◽  
DOMINIQUE LAURENCE
Keyword(s):  
Correlation Function ◽  
Exponential Model ◽  
Navier Stokes ◽  
Streamwise Direction ◽  
Relaxation Equation ◽  
Energy Redistribution ◽  
Elliptic Relaxation ◽  
Asymmetrical Shape ◽  
Correction Terms ◽  
Echo Effect

A channel flow DNS database at Reτ = 590 is used to assess the validity of modelling the redistribution term in the Reynolds stress transport equations by elliptic relaxation. The model assumptions are found to be globally consistent with the data. However, the correlation function between the fluctuating velocity and the Laplacian of the pressure gradient, which enters the integral equation of the redistribution term, is shown to be anisotropic. It is elongated in the streamwise direction and strongly asymmetric in the direction normal to the wall, in contrast to the isotropic, exponential model representation used in the original elliptic relaxation model. This discrepancy is the main cause of the slight amplification of the energy redistribution in the log layer as predicted by the elliptic relaxation equation. New formulations of the model are proposed in order to correct this spurious behaviour, by accounting for the rapid variations of the length scale and the asymmetrical shape of the correlation function. These formulations do not rely on the use of so-called ‘wall echo’ correction terms to damp the redistribution. The belief that the damping is due to the wall echo effect is called into question through the present DNS analysis.

Modeling Near-Wall Effects in Axially Rotating Pipe Flow by Elliptic Relaxation

AIAA Journal ◽  
10.2514/2.527 ◽  
1998 ◽  
Vol 36 (7) ◽  
pp. 1164-1170 ◽  
Author(s):  
B. A. Pettersson ◽  
H. I. Andersson ◽  
A. S. Brunvoll
Keyword(s):  
Pipe Flow ◽  
Wall Effects ◽  
Elliptic Relaxation ◽  
Rotating Pipe Flow ◽  
Near Wall

Numerical Investigation of Steady Density Currents Flowing Down an Incline Using v2¯−f Turbulence Model

2007 ◽  
Vol 129 (9) ◽  
pp. 1172-1178 ◽  
Author(s):  
Nima Khakzad ◽  
Bahar Firoozabadi ◽  
Bijan Farhanieh
Keyword(s):  
Turbulence Model ◽  
Momentum Equation ◽  
Density Currents ◽  
Governing Equations ◽  
Relaxation Equation ◽  
Elliptic Relaxation ◽  
High Reynolds ◽  
Volume Method ◽  
Dominant Parameter ◽  
Good Agreement

The governing equations of two-dimensional steady density currents are solved numerically using a finite volume method. The v2¯−f turbulence model, based on standard k−ε model, is used for the turbulence closure. In this method, all Reynolds stress equations are replaced with both a transport equation for v2¯ and an elliptic relaxation equation for f, a parameter closely related to the pressure strain redistribution term. The Simple-C procedure is used for pressure-velocity coupling. In addition, Boussinesq’s approximation is used to obtain the momentum equation. The computed height of the progressive density current is compared to the measured data in the literature, resulting in good agreement. The present results show that the flow rate is the most dominant parameter among those affecting the density currents hydrodynamics. The results also show that the v2¯−f turbulence model is able to predict and simulate the characteristics of the low Reynolds turbulent density currents successfully, although it is based on a high Reynolds number turbulence model, i.e., the standard k−ε model. The use of boundary layer convention, saying that the density current’s height is a height at which the concentration is ∼1% of the inlet concentration, seems to yield reasonable results.

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

The staining pattern of the tropomyosin sequence is displayed in a new paracrystal

1986 ◽  
Vol 44 ◽  
pp. 150-151
Author(s):  
M.K. Lamvik ◽  
L.L. Klatt
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Staining Pattern ◽  
Banding Patterns ◽  
Mass Thickness ◽  
New Form

Tropomyosin paracrystals have been used extensively as test specimens and magnification standards due to their clear periodic banding patterns. The paracrystal type discovered by Ohtsuki1 has been of particular interest as a test of unstained specimens because of alternating bands that differ by 50% in mass thickness. While producing specimens of this type, we came across a new paracrystal form. Since this new form displays aligned tropomyosin molecules without the overlaps that are characteristic of the Ohtsuki-type paracrystal, it presents a staining pattern that corresponds to the amino acid sequence of the molecule.

A New Form and Function for Personality

2013 ◽  
Author(s):  
Joshua Wilt ◽  
William Revelle
Keyword(s):  
Form And Function ◽  
New Form ◽  
And Function
Sign in / Sign up

Export Citation Format

Share Document