Bulletin of the American Physical Society
2005 58th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 20–22, 2005; Chicago, IL
Session NS: Turbulence Theory III |
Hide Abstracts |
Chair: Nigel Goldenfeld, University of Illinois, Urbana-Champaign Room: Hilton Chicago Stevens 4 |
Tuesday, November 22, 2005 11:01AM - 11:14AM |
NS.00001: Transient Growth for a Shear Flow Model Jeff Moehlis, Lina Kim We investigate transient growth due to the linear interaction between streaks and streamwise vortices for a nine-dimensional ordinary differential equation model for sinusoidal shear flow, in which fluid between two free-slip walls experiences a sinusoidal body force. We determine how such transient energy growth depends on initial conditions, Reynolds number, and aspect ratio, and also the importance of transient growth for turning on nonlinear effects which can lead to sustained turbulence. [Preview Abstract] |
Tuesday, November 22, 2005 11:14AM - 11:27AM |
NS.00002: An elliptise model for space-time correlations in turbulent shear flows Guo-wei He, Jin-bai Zhang An ellipse model for space-time correlations in turbulent shear flows is developed upon a second order approximation to the correlation contours, while Taylor's hypothesis implies a first order approximation. It suggests that the space-time correlations are mainly determined by their space correlations and two characteristic velocities: propagation velocity and sweeping velocity. If the two characteristic velocities are equal, Taylor's model for weak shear rate is obtained; if the propagation velocity vanishes, Kraichnan's model for isotropic turbulence is recovered. The data from the direct numerical simulation of turbulent channel flows supports the model: the normalization of time axis in terms of the ellipse model causes the good collapse of the all space-time correlations. [Preview Abstract] |
Tuesday, November 22, 2005 11:27AM - 11:40AM |
NS.00003: Roughness induced criticality in two and three dimensional turbulent pipe flows Nigel Goldenfeld, Nicholas Guttenberg Using an analogy with critical phenomena, we show that the data for the friction factor as a function of Reynolds number for rough turbulent three-dimensional pipe flows can be collapsed onto a single universal curve. Using momentum flux scaling arguments [1] taking into account the inverse and enstropy cascades, we calculate the scaling function for two- dimensional turbulent pipe flows, in particular the analogues of the Blasius and Strickler regimes. The roughness-induced criticality empirically obtained here hints at a deeper role of boundary roughness in understanding the scaling of turbulent flows.\newline \newline [1] G. Gioia and Pinaki Chakraborty, ``Turbulent friction in rough pipes and the energy spectrum of the phenomenological theory.'' March 17, 2005. Preprint. [Preview Abstract] |
Tuesday, November 22, 2005 11:40AM - 11:53AM |
NS.00004: Dilute polymers in wall bounded flows: energy transfer i and spatial fluxes Carlo Massimo Casciola, Elisabetta De Angelis, Nicoletta Marati, Renzo Piva The single most significant aspect of Newtonian turbulence is the kinetic energy transfer through the scales. For dilute polymers solutions, kinetic energy is removed from certain scales to sustain the fluctuations in the micro-structure. In addition, applications are often characterized by a combination of shear and inhomogeneity, like e.g. for drag reduction in wall bounded flows. The large scale anisotropy is responsible for the production of turbulence while inhomogeneity generates spatial fluxes of energy. These complex interactions are addressed starting from a suitably generalized form of the classical Kolmogorov equation. A scale-by-scale budget for the turbulent fluctuations is evaluated to examine how the energy of a specific scale of motion is transferred through the spectrum of scales, how it is fed by the interaction with the large scale shear and exchanges energy with the spatial flux and with the polymers. The analysis is applied to data sets from direct numerical simulations (DNS) of a viscoelastic channel flow, and the results compared with those of homogeneous isotropic conditions. The detailed scale-by-scale balance is used to understand how - i.e. through which mechanisms, at which scales and in which regions of the flow domain - turbulent fluctuations are generated and sustained. [Preview Abstract] |
Tuesday, November 22, 2005 11:53AM - 12:06PM |
NS.00005: Pair Dispersion in Turbulence Eberhard Bodenschatz, Mickael Bourgoin, Nicholas Ouellette, Haitao Xu, Jacob Berg We report measurements of relative dispersion in a high Reynolds number water flow using 3D optical particle tracking. We find excellent agreement with Batchelor's theorertical predictions, and do not see a fully developed Richardson law. Our results indicate that the initial separation of particle pairs is an important parameter for calculating dispersion in any flow of industrial or biological significance. This work is supported by the NSF and by the Max Planck Society. [Preview Abstract] |
Tuesday, November 22, 2005 12:06PM - 12:19PM |
NS.00006: The scouring of granular beds by jet-driven turbulent cauldrons Fabi\'an Bombardelli, Gustavo Gioia We study a sustained, jet-driven, cylindrical or axisymmetric turbulent cauldron that scours a cohesionless granular bed to form a pothole. We focus on the energetics of the turbulent cauldron and use dimensional analysis and similarity methods to derive (up to a multiplicative constant) a formula for the equilibrium depth of the pothole. The formula contains a single similarity exponent, which we show can be determined via the phenomenological theory of turbulence. Our derivation affords insight into how a state of dynamic equilibrium is attained between a granular bed and a localized turbulent flow. Our method of analysis may prove useful in developing a theoretical understanding of mine burial, bridge pier-induced erosion, and other applications in which a localized turbulent flow interacts with a granular bed. [Preview Abstract] |
Tuesday, November 22, 2005 12:19PM - 12:32PM |
NS.00007: High speed MHD turbulence in aerospace applications Foluso Ladeinde, Datta Gaitonde A large proportion of the fundamental work on MHD turbulence focused on astrophysical applications, in contrast to aerospace engineering applications that are of primary interest in our work. We examine the turbulence scales of the important phenomena in MHD systems for the two fields of application, in order to motivate the vastly different physics expected and discuss how the knowledge gained in astrophysical MHD turbulence may not be of much help to the aerospace engineer whose objective is to explore the possibility of using MHD to control the flow over space vehicles. We examine the cascade process, with a focus on low magnetic Reynolds numbers, which is the limit of interest in aerospace engineering. The effects of anisotropy in three-dimensional MHD turbulence when a mean magnetic field is imposed will be discussed from the standpoint of scaling and dynamic similarity. Preliminary work on anisotropy in low magnetic Reynolds number, high speed MHD turbulence will be presented. [Preview Abstract] |
Tuesday, November 22, 2005 12:32PM - 12:45PM |
NS.00008: Reconstruction of flow topology and percolation scalings Oleg Bakunin The essential deviation of transport processes in turbulent fluids and plasma from the classical behavior leads to the necessity of search for new approaches and scaling laws [1]. A variety of turbulence forms requires not only special description methods, but also an analysis of general mechanisms for different turbulence types. One such mechanism is the percolation transport [1,2]. Its description is based on the idea of long-range correlations, borrowed from theory of phase transitions and critical phenomena. The present paper considers the influence of zonal flow and time-dependence effects on the passive scalar behavior in the framework of the percolation approach. It is suggested to modify the renormalization condition of the small parameter of percolation model in accordance with the additional external influences superimposed on the system [3-4]. This approach makes it possible to consider simultaneously both parameters: the characteristic drift velocity $U_{d}$ and the characteristic perturbation frequency $w.$ The effective diffusion coefficient $D_{eff }$\textit{$\sim $ w}$^{7/10}$ satisfactory describes the low-frequency region $w$ in which the long-range correlation effects play a significant role. This scaling agrees well with the analogous expressions that describe low frequency regimes of transport [1,2]. [1] Isichenko M B 1992 \textit{Rev. Mod. Phys}. 64 961 [2] Bakunin O G 2004 \textit{Reports on Progress in Physics} \textbf{67} 965 [3] Bakunin O G 2005 \textit{Physica }A \textbf{345} 1 [4] Bakunin O G 2005 \textit{J. Plasma Physics } \textbf{71} 756. [Preview Abstract] |
Tuesday, November 22, 2005 12:45PM - 12:58PM |
NS.00009: Numerical verification of the possibility of application of Clebsch transformation to the non-canonical Hamiltonian systems Yeontaek Choi, Changhoon Lee The Clebsch transformation is a well-known gauge transformation in fluid mechanics. One can derive a useful and controllable equation system (e.g. four wave system in Wave Turbulence) from the original one through using Clebsch variables. But because of the non-uniqueness and the locality of the Clebsch fields, there are some limitations to their application to the non- canonical dynamical system such as the Navier-Stokes equation (NSE), although the Clebsch transformation plays a crucial role in the case of inviscid and incompressible fluid system. We study the Clebsch variables numerically, i.e. through the direct numerical simulations of isotropic homogeneous turbulence we investigate the possibility of the application to the non-local conjugate variable system, e.g. NSE. Therefore we will predict numerically the extent of the locality of the Clebsch fields. This means we can have a criteria to apply those transformations to the NSE turbulence structure. [Preview Abstract] |
Tuesday, November 22, 2005 12:58PM - 1:11PM |
NS.00010: Unstable recurrent patterns in Kuramoto-Sivashinsky dynamics Predrag Cvitanovic', Yueheng Lan We test the ``recurrent patterns'' description of turbulence on a Kuramoto-Sivashinsky model, deploying a new variational method that yields a large number of numerical unstable spatiotemporally periodic solutions. For a small but turbulent system, the attracting set appears surprisingly thin. Its backbone are several Smale horseshoe repellers, well approximated by local return maps, each with good symbolic dynamics. Global dynamics appears decomposable into chaotic dynamics within such local repellers, interspersed by infrequent transitions between them. [Preview Abstract] |
Tuesday, November 22, 2005 1:11PM - 1:24PM |
NS.00011: Atomic Weight Effects in Turbulence Onset as a Continuous Phase Transition Joseph Johnson III, Ephrem Mezonlin, Jean Orou Chabi When there is a mass dependence in the Gibbs free energy for a system experiencing a continuous phase transition, such mass dependence can influence the behavior in critical parameters. Even when the cause cannot be easily identified, atomic weight sensitivity has often been found to be a reliable feature of such systems such as, e.g., the $Tc=1/\sqrt{M}$ behavior in Type II superconductors. Since lamda-like behavior is observed in the evolution of several turbulence parameters, we have determined the circumstances under which various atomic weight influences might be expected in near-critical-like regimes for turbulence onset. Specifically, we explore the dynamics through which local atomic-level interactions produce turbulence constrained by local atomic weights. Comparisons are made between the theoretical predictions and experimental data from turbulent plasmas and gases. [Preview Abstract] |
Tuesday, November 22, 2005 1:24PM - 1:37PM |
NS.00012: Bounds on double diffusive convection Atichart Kettapun, Neil Balmforth, Shilpa Ghadge, Shreyas Mandre We consider double-diffusive convection between two parallel plates and compute bounds on the flux of the unstably stratified species using the background method. The bound on the heat flux for Rayleigh-B\'enard convection also serves as a bound on the double-diffusive problem (with the thermal Rayleigh number equal to that of the unstably stratified component). In order to incorporate a dependence of the bound on the stably stratified component, an additional mixed energy constraint has to be included, like the one used by Joseph (1976) to improve the energy stability of this system. Our bound extends Joseph's result beyond his energy stability boundary. Exactly on the energy stability boundary, we find a jump in the bound suggestive of the appearance of new finite-amplitude solutions in a saddle-node bifurcation, although the result is obscured by further discontinuity introduced because we use piece-wise linear optimizing profiles for the diffusing fields. At large Rayleigh number, the bound is found to behave like $R_T^{1/2}$ for fixed ratio $R_S/R_T$, where $R_T$ and $R_S$ are the Rayleigh numbers of the unstably and stably stratified components, respectively. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700