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Schedule
International Symposium on Near-Wall Flows: Transition and Turbulence
June 20 (Monday)
13:20-13:30 Opening remarks 13:30-14:30“New scaling predictions for turbulent boundary layers based on the hierarchical random additive process” Charles Meneveau (Johns Hopkins University) 14:30-15:00“Effects of spatial development on skin friction drag reduction control at a turbulent boundary layer” Yosuke Hasegawa (The University of Tokyo) 15:00-15:30 Coffee break 15:30-16:30“Deconstructing and reconstructing wall turbulence using a “linear” template” Beverley J. McKeon (California Institute of Technology) 16:30-17:00“Opportunities for large-scale control of turbulent boundary layers” Nicholas Hutchins (University of Melbourne)June 21 (Tuesday)
9:00-10:00“High Reynolds number turbulent boundary layers over smooth and rough surfaces” Ivan Marusic (University of Melbourne) 10:00-10:30“Large and small-scale interactions in high Reynolds number turbulent boundary layer; comparison with velocity and pressure fluctuations” Yoshiyuki Tsuji (Nagoya University) 10:30-11:00 Coffee break 11:00-12:00“Wall-bounded turbulence is not due to the wall” Javier Jimenez (Universidad Politecnica de Madrid) 12:00-13:30 Lunch break 13:30-14:00“Thin shear layers observed in the DNS of high Reynolds number turbulence” Takashi Ishihara (Nagoya University), Koji Morishita (Kobe University) and Julian C.R. Hunt(University College London) 14:00-14:30“History effects in adverse pressure gradient turbulent boundary layers” Ramis Orlu, Ricardo Vinuesa, Carlos Sanmiguel Vila, Alexandra Bobke, Stefano Discetti, Andrea Ianiro and Philipp Schlatter (KTH) 14:30-15:00“DNS of a turbulent boundary layer with separation and reattachment over a wide range of Reynolds numbers” Hiroyuki Abe (JAXA) 15:00-15:30 Coffee break 15:30-16:00 Poster introduction 16:00-17:00 Poster session 1. “The mean velocity profile in turbulent slugs” Rory Cerbus (OIST), Chien-chia Liu (OIST), Jun Sakakibara (Meiji Univ.),Gustavo Gioia (OIST) and Pinaki Chakraborty (OIST) 2. “Macroscopic non-universality in turbulent plane-Couette flows” Dongrong Zhang, Gustavo Gioia and Pinaki Chakraborty (OIST) 3. “Onset of chaotic reversals in thermal convection” Kentaro Cho, Masaki Shimizu and Genta Kawahara (Osaka Univ.) 4. “Numerical and experimental study of turbulent helical pipe flows” Anup Kumer Datta (Okayama Univ.), Yasutaka Hayamizu (Yonago College), Toshinori Kouchi (Okayama Univ.), Yasunori Nagata (Okayama Univ.), Kyoji Yamamoto(Okayama Univ.) and Shinichiro Yanase (Okayama Univ.) 5. “Turbulent stripe pattern in Poiseuille flow at transitional region” Koji Fukudome (Ritsumeikan Univ.), Takahiro Tsukahara (Tokyo Univ. of Science) and Yoshifumi Ogami(Ritsumeikan Univ.) 6. “Mean velocity profile and friction factor for fully developed pipe flow at high Reynolds number” N. Furuichi(AIST, NMIJ), Y. Terao(AIST, NMIJ), Y. Wada(Nagoya Univ.) and Y. Tsuji(Nagoya Univ.) 7. “Turbulent Poiseuille flows in a spanwise minimal flow unit” at low Reynolds Kento Higashitsutsumi (Ritsumeikan Univ.) Koji Fukudome (Ritsumeikan Univ.), Yohann Duguet (LIMSI-CNRS) and Yoshifumi Ogami (Ritsumeikan Univ.) 8. “Large time scale motion of spatially-localized turbulence and its change of direction in two-dimensional Kolmogorov flow” Yoshiki Hiruta and Sadayoshi Toh (Kyoto Univ.) 9. “Effect of Roughness Sub-layer to the Mean Flow Properties” in a Turbulent Boundary Layer Takatsugu Kameda (Kindai Univ.) and Shinsuke Mochizuki (Yamaguchi Univ.) 10.“Strong dependence of the lifetime with the domain size” in plane channel flow Takahiro Kanazawa, Masaki Shimizu and Genta Kawahara (Osaka Univ.) 11.“Transitional structures in sliding Couette flow with full and hypothetical circumference” Kohei Kunii, Takahiro Ishida and Takahiro Tsukahara (Tokyo University of Science) 12.“Upper bound for heat transfer in plane Couette flow” Shingo Motoki, Genta Kawahara and Masaki Shimizu (Osaka Univ.) 13.“An experimental study on development of perturbations” Yuji Tasaka (Hokkaido Univ.), Jumpei Ohkubo, Yuichi Murai and Tom Mullin 14.“Turbulent boundary layer with a linear velocity profile far from a wall generated by functinal Riblets” Youko Toriumi, Yohei Inoue and Hiroshi Maekawa (The Univ. Elec. Comm.) 15.“An unprecedented turbulent state in plane Couette flow” Daiki Watanabe, Genta Kawahara and Masaki Shimizu (Osaka Univ.) 19:00 BanquetJune 22 (Wednesday)
9:00-10:00“Towards a model of large scale dynamics in transitional wall-bounded flows” Paul Manneville (CNRS, Kyoto University) 10:00-10:30“Experimental investigations of large-scale feature in channel flow at low Reynolds number” Masaharu Matsubara (Shinshu University) 10:30-11:00 Coffee break 11:00-12:00“Rotating plane Couette flow? -instabilities, structures and turbulence” Henrik Alfredsson (KTH) 12:00-13:30 Lunch break 13:30-14:30“Many paths to turbulence in plane Poiseuille flow” Bruno Eckhardt (Philipps-Universitat Marburg) 14:30-15:00“Laminar-turbulent pattern in annular/plane channel flows” Takahiro Tsukahara (Tokyo University of Science) 15:00-15:30 Coffee break 15:30-16:30“High Reynolds number analysis of 3D traveling wave solutions in shear flows” Fabian Waleffe (University of Wisconsin-Madison) 16:30-16:40 Closing remarks
Abstracts of Invited Talks
“New scaling predictions for turbulent boundary layers based on the hierarchical random additive process”
Charles Meneveau (Johns Hopkins University)
We describe a simple additive hierarchical process of space-filling wall-attached eddies and explore
its predictions for the statistics of streamwise velocity fluctuations in turbulent boundary layers
at high Reynolds numbers. We consider both standard statistics such as high-order moments and structure
functions, as well as new objects such as generalized mixed two-point moments and moment-generating
functions (MGF1s). New logarithmic laws are predicted for the generalized mixed two-point moments,
and power laws are predicted for the MGF1s, including a scaling transition due to the hierarchical nature
of the process. Predictions are compared with results from data analysis on the Melbourne wind tunnel data.
This work has been done with Xiang Yang and Ivan Marusic.
Yosuke Hasegawa (The University of Tokyo)
So far, most turbulence control strategies for skin friction drag reduction have been developed
in a fully developed turbulent channel flows due to its simple configuration, i.e., two periodic conditions
in the streamwise and spanwise directions. Meanwhile, since practical flows are spatially developing flows
in general, it is important to clarify how the existing control schemes perform in a turbulent boundary layer.
In the present talk, we apply conventional control strategies to a turbulent boundary layer and report similarity
and fundamental differences between a fully developed channel
flow and a spatially developing a turbulent boundary layer.
Beverley J. McKeon (California Institute of Technology)
The systems analysis of turbulent pipe flow proposed by McKeon & Sharma (J. Fluid Mech, 2010) provides a simple model by which to deconstruct the full turbulence field into a linear combination of (interacting) modes. After a brief review of some key results that can be obtained by analysis of the linear resolvent operator concerning the statistical and structural make-up of natural and synthetic wall turbulence, I will describe some of our recent progress towards determining how to correctly reconstruct the flow by identifying the nonlinear forcing required to obtain a self-sustaining turbulent system.Implications for both the classical picture of wall turbulence and control of turbulent flows will be discussed.
Nicholas Hutchins (University of Melbourne)
There has been much recent work on large-scale structures in wall-bounded turbulence. These features are known to increase in strength with Reynolds number and also interact with the near-wall coherent cycle and the interfacial bulging. It is expected that as Reynolds number increases an increasing proportion of total turbulence production will be due to these features. Based on this, numerous studies are currently underway to interact with or perturb these large-scale features. This talk will provide an overview of preliminary ongoing work involving various control methodologies at Melbourne University, including active large-scale opposition control, outer layer manipulations and surface textures that are both anisotropic (directional) and heterogeneous (spanwise varying).
Ivan Marusic (University of Melbourne)
Turbulent boundary layer measurements above a smooth wall and sandpaper roughness are presented across a wide range of friction Reynolds numbers, $\delta_{99}^+$, and equivalent-sandgrain-roughess Reynolds numbers, $k_s^+$ (smooth-wall: $2\,020 \leq \delta_{99}^+ \leq 21\,430$, rough-wall: $2\,890 \leq \delta_{99}^+ \leq 29\,900$; $22 \leq k_s^+ \leq 155$; and $28 \leq \delta_{99}^+/k_s^+ \leq 199$). For the rough-wall measurements, the mean wall shear stress is determined using a floating element drag balance. Detailed comparison are made between the smooth and rough-wall cases, including measurements made using multi-component hot-wires and large and small-field PIV.
Yoshiyuki Tsuji (Nagoya University)
The interaction between large and small scale motions in velocity and pressure fluctuation is studied experimentally. Using the small pressure probe, both the static pressure and wall pressure fluctuations were measured inside the zero-pressure gradient boundary layer at relatively high Reynolds numbers. Especially, the pressure gradient was measured by two probes which represents the small-scale, and they are compared with that of velocity. Pressure difference between wall and static pressure indicates the large scale motions. How the large scales in log-region affect the small scales near wall is analyzed by means of amplitude and frequency modulation procedure. Analyzing the wall pressure fluctuations, it was found that the amplitude is not large compared with those of velocity, and large-scale interacts with small-scale but there is a time-lag between them.
Javier Jimenez (Universidad Politecnica de Madrid)
The roughly three decades of direct numerical simulations of wall-bounded turbulence and other shear flows have generated a large repository of flow data that goes well beyond that available from experiments, and that is beginning to provide reasonably definite conclusions about the flow dynamics. This seminar explores the question of whether wall-bounded turbulence is driven by processes in the near-wall region, and diffuses outwards, or originates outside and grows inwards. The latter appears to be the case. The driving mechanism is ambient shear, and the resulting self-sustaining cycle is active throughout a shear-dominated layer that roughly coincides with the classical logarithmic region. The near-wall region, defined as the layer where viscosity is relevant to lowest order, is important to the overall energetics of the flow, but is not dominant, especially at high Reynolds numbers. Its main roles appear to be to enforce the no-slip condition that creates the shear, and the impermeability condition that sets the length scales and inhibits modal instability, forcing the flow into transient and nonlinear self-sustaining mechanisms.
Takashi Ishihara (Nagoya University), Koji Morishita (Kobe University)
and Julian C.R. Hunt (University College London)
DNS data of homogeneous isotropic turbulence (HIT)(Rλ = 1100), turbulent channel flow (TCF)(Rτ= 5120), and turbulent boundary layer (TBL)(Rθ = 900 ? 2000) are used to study the properties of three different types of thin shear layers; at the outer edge (T/NT), in the interior (T/T) and within the buffer layer near the wall (T/W). Analysis of the HIT data has shown that in T/T there are high-enstrophy, micro-scale vortex tube structures. Strong energy dissipation and high net energy transfer with large fluctuations are observed within the T/T and there is a net energy flux into the small scale eddies within the thin layers from the larger scale motions outside the layer. These layers have thicknesses of the order of the Taylor micro-scale, and the interfaces at the outside of the layers act as a partial barrier to the fluctuations on either side of the layers. The TCF data shows that sharp T/T layers that have big streamwise velocity jump are observed at y+ = O(1000) in a log-law region. By an appropriate thresholding based on normalized vorticity, we can define the location of T/NT and T/W layers of the TBL. The average height of T/NT interface is 0.8δ (δ is boundary layer thickness) and that of T/W interface is of the order of 10 in wall unit. Analysis of the TBL data has shown that the T/NT transient region with thickness of the order of the Taylor-micro scale has a rotational/irrotational transient superlayer that scales with the Kolmogorov length at the outer edge. The TBL data shows that de-correlation of velocity fluctuation is stronger at the T/W interface than at the T/NT interface of TBL.
Ramis Orlu, Ricardo Vinuesa, Carlos Sanmiguel Vila, Alexandra Bobke,
Stefano Discetti, Andrea Ianiro, and Philipp Schlatter (KTH)
The present investigation focusses on the concerted investigation of upstream history (tripping and curvature) and pressure gradient effects on turbulent boundary layers. In particular, a number of direct and large-eddy simulations and wind tunnel experiments with covering a wide range of pressure gradient parameters, streamwise histories and Reynolds numbers is performed. Results are aimed at isolating the effects of pressure gradients, streamwise curvature and streamwise (pressure gradient) histories, which have traditionally inhibited to draw firm conclusions when it comes to adverse pressure gradient turbulent boundary layers.
Hiroyuki Abe (JAXA)
We have recently performed direct numerical simulations (DNSs) of a turbulent boundary layer separating from a flat plate and reattaching with inlet data generated by rescaling-recycling at Re_\theta=300, 600 and 900 (Abe et al. 2015). The focus is put on massive separation and the set-up close to those of Spalart & Coleman (1997) and Na & Moin (1998) at lower Reynolds number. This extends the work of Abe et al. (CTR Annual Brief, 2012) but removes the stagnation point, present over the bubble and due to strong blowing and suction at the upper boundary. Here we analyze the DNS data and discuss the behavior of the bubble and its Reynolds number dependence. It is shown that while turbulent kinetic energy becomes large in the shear layer, it is reduced near at the top of the bubble with negative turbulent production where Reynolds stresses do not catch up with rapid change of mean strain rate. It is also shown that inviscid transport is dominated over the bubble, which is essentially associated with the delay of maximum Reynolds shear stress known to appear after the reattachment. At all three Re_\theta, separation and reattachment locations are nearly identical. Significant Re dependence does however appear in the skin friction coefficient in the region after reattachment due to the weak development of near-wall turbulence. We also discuss the breathing motion (i.e. contraction/expansion) of the bubble by comparing with recent experimental work of Weiss et al. (2015) who indicated the presence of very low frequency global motion akin to that in the shock wave/turbulent boundary layer interactions even in the pressure induced separation bubble at Re_\theta \simeq 5000.
Paul Manneville (CNRS, Kyoto University)
A system of simplified equations is proposed to govern the feedback interactions of large-scale flows present in laminar-turbulent patterns of transitional wall-bounded flows, with small-scale Reynolds stresses generated by the self-sustainment process of turbulence, itself modeled using an extension of Waleffe’s low-order model.
Masaharu Matsubara (Shinshu University)
Large-scale feature in transitional and turbulent channel flow has been investigated. Hot-wire measurements in two air channel facilities show that distributions of velocity spectra have a peak or a hump at low frequency. Furthermore, in flow visualization of water channel, clusters of streaks are confirmed. These results strongly suggest existence of large-scale feature at not only very high but also low Reynolds number.
Henrik Alfredsson (KTH)
Shear flows subjected to system rotation, where the rotation axis is parallel with the mean-flow vorticity, are influenced by a Coriolis force, which may have a strong effect on the flow field even at low rotation rates. Here we will discuss plane Couette flow (PCF) under anticyclonic rotation both in the laminar and turbulent regimes. Without rotation, PCF is linearly stable for all Reynolds numbers however in experiments transition to turbulence is observed around Re=350. With anticyclonic rotation, the critical Reynolds number is as low as 20.6, at which point the flow bifurcates to a flow with streamwise-oriented roll cells. With increasing Reynolds number and/or rotation rate, the laminar roll cells develop various types of other complex instabilities and at higher Reynolds numbers the flow enters a turbulent regime, although it is still dominated by streamwise roll cells.
Experimental results are presented where all three velocity components are measured with stereoscopic PIV, enabling determination of the mean flow and all four non-zero Reynolds stresses across the central parts of the channel. We discuss the resulting flow structures as well as an analysis of the Reynolds-stress equations and how they relate to the fact that the absolute vorticity, i.e. the sum of the averaged spanwise-flow vorticity and system rotation, tends to zero in the central region of the channel for high enough rotation rates.
Bruno Eckhardt (Philipps-Universitat Marburg)
Plane Couette flow offers a unique laboratory for the investigation of various paths to turbulence and their interactions. In particular, we will discuss the various critical Reynolds numbers connected with different dimensionalities and transition mechanisms. We will also discuss the interaction between Tollmien-Schliching and bypass transitions, as well as the different spatio-temporal patterns in spatially extended systems.
Takahiro Tsukahara (Tokyo University of Science)
Subcritical transition of channel flow between two parallel plates often exhibits a large-scale pattern of coexisting laminar and turbulent regions as a metastable state. The pattern takes a form of oblique band(s) or stripe that are oblique against the streamwise direction with an almost constant angle. Recent studies have demonstrated this laminar-turbulent pattern as a ubiquitous feature of the route to turbulence in wall-bounded shear flows. In this talk, we show variations of the pattern
depending on the Reynolds number and on the flow geometry (i.e., plane channel, annular, and approximately-pipe flows).
Fabian Waleffe (University of Wisconsin-Madison)
A semi-circle theorem for streaky flow will be proved and presented together with an asymptotic analysis of the spectrum of 3D traveling wave solutions.
