Influence of the turbulence structure on the particle sedimentation in wall-bounded flows

2007 ◽  
pp. 373-384 ◽  
Author(s):  
M. Cargnelutti ◽  
L. M. Portela
Keyword(s):  
Turbulence Structure ◽  
Particle Sedimentation ◽  
Wall Bounded Flows

Moment generating functions and scaling laws in the inertial layer of turbulent wall-bounded flows

2016 ◽  
Vol 791 ◽  
Author(s):  
Xiang I. A. Yang ◽  
Ivan Marusic ◽  
Charles Meneveau
Keyword(s):  
Power Law ◽  
Generating Functions ◽  
Scaling Laws ◽  
Single Point ◽  
Streamwise Velocity ◽  
Turbulence Structure ◽  
Additional Information ◽  
Moment Generating Functions ◽  
Wall Bounded Flows ◽  
Turbulent Wall

Properties of single- and two-point moment generating functions (MGFs) are examined in the inertial region of wall-bounded flows. Empirical evidence for power-law scaling of the single-point MGF $\langle \text{exp}(qu^{+})\rangle$ (where $u^{+}$ is the normalized streamwise velocity fluctuation and $q$ a real parameter) with respect to the wall-normal distance is presented, based on hot-wire data from a $Re_{{\it\tau}}=13\,000$ boundary-layer experiment. The parameter $q$ serves as a ‘dial’ to emphasize different parts of the signal such as high- and low-speed regions, for positive and negative values of $q$, respectively. Power-law scaling $\langle \text{exp}(qu^{+})\rangle \sim (z/{\it\delta})^{-{\it\tau}(q)}$ can be related to the generalized logarithmic laws previously observed in higher-order moments, such as in $\langle u^{+2p}\rangle ^{1/p}$, but provide additional information not available through traditional moments if considering $q$ values away from the origin. For two-point MGFs, the scalings in $\langle \text{exp}[qu^{+}(x)+q^{\prime }u^{+}(x+r)]\rangle$ with respect to $z$ and streamwise displacement $r$ in the logarithmic region are investigated. The special case $q^{\prime }=-q$ is of particular interest, since this choice emphasizes rare events with high and low speeds at a distance $r$. Applying simple scaling arguments motivated by the attached eddy model, a ‘scaling transition’ is predicted to occur for $q=q_{cr}$ such that ${\it\tau}(q_{cr})+{\it\tau}(-q_{cr})=1$, where ${\it\tau}(q)$ is the set of scaling exponents for single-point MGFs. This scaling transition is not visible to traditional central moments, but is indeed observed based on the experimental data, illustrating the capabilities of MGFs to provide new and statistically robust insights into turbulence structure and confirming essential ingredients of the attached eddy model.

scholarly journals Origin of the Turbulence Structure in Wall-Bounded Flows, and Implications toward Computability

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 333
Author(s):  
T.-W. Lee
Keyword(s):  
Turbulent Flows ◽  
Coordinate Frame ◽  
Turbulence Structure ◽  
Pressure Gradients ◽  
Boundary Layer Flows ◽  
Mean Velocity ◽  
Basic Physics ◽  
Symmetric Set ◽  
Wall Bounded Flows ◽  
Turbulence Transport

Coordinate-transformed analysis of turbulence transport is developed, which leads to a symmetric set of gradient expressions for the Reynolds stress tensor components. In this perspective, the turbulence structure in wall-bounded flows is seen to arise from an interaction of a small number of intuitive dynamical terms: transport, pressure and viscous. Main features of the turbulent flow can be theoretically prescribed in this way and reconstructed for channel and boundary layer flows, with and without pressure gradients, as validated in comparison with available direct numerical simulation data. A succinct picture of turbulence structure and its origins emerges, reflective of the basic physics of momentum and energy balance if placed in a specific moving coordinate frame. An iterative algorithm produces an approximate solution for the mean velocity, and its implications toward computability of turbulent flows is discussed.

Similarities of Turbulence Structure in a Conical Diffuser with Other Wall-Bounded Flows

AIAA Journal ◽  
1979 ◽  
Vol 17 (8) ◽  
pp. 884-891 ◽  
Author(s):  
R. S. Azad ◽  
R. H. Hummel
Keyword(s):  
Turbulence Structure ◽  
Conical Diffuser ◽  
Wall Bounded Flows

Statistical Analysis of the Turbulence Structure Downstream of a Short Roughness Strip

2007 ◽  
Vol 34 (2) ◽  
pp. 179-190
Author(s):  
M. O. Oyewola ◽  
M. S. Adaramola ◽  
A. O. Olaberinjo ◽  
O. A. Obiyemi
Keyword(s):  
Statistical Analysis ◽  
Turbulence Structure ◽  
Roughness Strip

Turbulence structure in the spiral wake shed by a lifting wing

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 658-660
Author(s):  
Joseph A. Miranda ◽  
William J. Devenport
Keyword(s):  
Turbulence Structure

k-zeta (enstrophy) compressible turbulence model for mixing layers and wall bounded flows

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1221-1224
Author(s):  
G. A. Alexopoulos ◽  
H. A. Hassan
Keyword(s):  
Turbulence Model ◽  
Mixing Layers ◽  
Compressible Turbulence ◽  
Wall Bounded Flows

Subgrid-scale models for large-eddy simulations of compressible wall bounded flows

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1340-1350 ◽  
Author(s):  
E. Lenormand ◽  
P. Sagaut ◽  
L. Ta Phuoc ◽  
P. Comte
Keyword(s):  
Large Eddy Simulations ◽  
Subgrid Scale ◽  
Scale Models ◽  
Large Eddy ◽  
Wall Bounded Flows
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