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Summer Program : Sunday, June 24, 2018 - 9:00am : Speaker(s): Parviz Moin, Director of Center for Turbulence Research
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 The Center for Turbulence Research invites applications for participation in its 17th biennial Summer Program. The objective of the Summer Program is to promote development and evaluation of new ideas in fluid mechanics with emphasis on turbulent flows. It is expected that the novel concepts and preliminary results generated during the Summer Program will be of sufficiently high caliber to lead to journal publications and to provide grounds for opening new lines of research in the participants' home institutions. 

In recent years a significant numb... Read More

Tea Seminar : Friday, May 18, 2018 - 4:30pm : Speaker(s): Dr. Immanuvel Paul
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Fractal-grid-generated turbulence has gained considerable attention in the past decade owing to its novel unique characteristics including the nonequilibrium energy cascade present in the near field. This talk will present direct numerical simulation results of turbulence generated by a simplified fractal grid called a square grid-element.
                     
This talk consists of three parts. The first part focuses on the small-scale dynamics of grid-element turbulence. Specifically, the generating... Read More
Bio:
Dr. Immanuvel Paul obtained his PhD from Imperial College London in May 2017. He has been working on fractal-grid-generated turbulence, fine-scale structure of fluid and scalar turbulence, numerical... Read More
Tea Seminar : Friday, May 4, 2018 - 4:30pm : Speaker(s): Dr. Xiaojue Zhu
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In this talk, Dr. Zhu will present "the newest results" on fully developed Rayleigh-Bénard turbulence. For the first time in numerical simulations we find the transition to the ultimate regime, namely at Ra*= 10^13. We reveal how the emission of thermal plumes enhances the global heat transport, leading to a steeper increase of the Nusselt number than the classical Malkus scaling. Beyond the transition, the temperature profiles are only locally logarithmic, namely within the regions where plumes are emitted, and where the local Nusselt number has an effective scaling exponent of 0.38 with r... Read More

Bio:
Dr. Xiaojue Zhu obtained his PhD in February 2018 from the Physics of Fluids Group at the University of Twente in the Netherlands. He is currently a postdoctoral researcher in the same group. His... Read More
Tea Seminar : Friday, April 27, 2018 - 4:30pm : Speaker(s): Dr. Adrian Lozano-Duran
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At first sight, walls appear as the most relevant ingredient in turbulence confined or limited by solid surfaces, and it seems plausible to assume that they should be the origin and organizing agent of wall-bounded turbulence.  Consequently, many efforts have been devoted to understand the structure of turbulence in the vicinity of walls.  Particularly interesting is the region within the so-called log-layer, where most of the dissipation resides in the asymptotic limit of infinite Reynolds number.

In the present work, the role of the wall and mean momentum transfer on the outer laye... Read More

Bio:
Dr. Adrian Lozano-Duran received his PhD from the Technical University of Madrid in 2015 at the Computational Fluid Mechanics Lab. headed by Professor Jiménez. His main research has focused on... Read More
Tea Seminar : Friday, April 6, 2018 - 4:30pm : Speaker(s): Dr. Perry Johnson
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Turbulence modeling has traditionally relied heavily on the eddy viscosity concept relating turbulent fluxes to local gradients. Important deficiencies of the eddy viscosity concept include its inability to capture non-local and memory effects of turbulence. This has motivated recent interest in exploring how fractional derivatives (derivatives with non-integer order) may be helpful in generalizing the eddy viscosity concept to include non-local effects. Building on the speculative work of Chen (Chaos 16, 023126, 2006), a recent study by Epps & Cushman-Roisin has provided a systematic d... Read More

Bio:
Dr. Perry Johnson earned his PhD in Mechanical Engineering at Johns Hopkins, and he was awarded the 2017 Corrsin-Kovasznay Outstanding Paper Award. He joined CTR as a postdoctoral scholar September... Read More
Tea Seminar : Friday, March 16, 2018 - 4:30pm : Speaker(s): Dr. Zhu Huang
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The minimal seeds (the disturbance with the lowest energy which triggers turbulence) for plane shear flows have been captured by the variational method dealing with the nonlinear Navier-Stokes equations. The subcritical transition of plane Poiseuille flow and the fluid structures of minimal seed are explored in the Reynolds number range 1500 ≤ Re ≤ 5000, the energy threshold of minimal seed scales Re-3 with respect to Re which agrees well with the theoretical prediction and the direct numerical simulations. The minimal seeds and the generated coherent structures corresponding to... Read More

Bio:
Dr. Zhu Huang is a Postdoctoral Fellow of the Center for Turbulence Research at Stanford University. He earned his Ph.D. degree in Power Engineering and Engineering Themophysics from Xi’an Jiaotong... Read More
Tea Seminar : Friday, March 2, 2018 - 4:30pm : Speaker(s): Professor V. Kumaran
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It is well known that the transition from a laminar to a turbulent flow takes place in a rigid tube takes place at a Reynolds number of about 2100, and in a rigid channel at a Reynolds number of about 1200. Experimental results are presented to show that the transition Reynolds number could be as low as low as 200 in micro-channels of height 100 microns with a soft wall, provided the elasticity modulus of the wall is sufficiently low. At the point of transition, motion is observed in the walls of the channel/tube, indicating that the instability is caused by a dynamical coupling between the... Read More

Bio:
Dr. Viswanathan Kumaran is the Senior Professor (HAG scale) & J. C. Bose National Chair, Department of Chemical Engineering, Indian Institute of Science, Bangalore since November 2010. His areas... Read More
Tea Seminar : Friday, February 23, 2018 - 4:30pm : Speaker(s): Dr. Lluis Jofre-Cruanyes
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Large-eddy simulation (LES) has gained significant importance as a high-fidelity technique for the numerical resolution of complex turbulent flow. The low-pass filtering of the conservation equations significantly reduces the computational cost of solving turbulence, however, at the expense of modeling the subgrid-scale (SGS) physics. In consequence, the assumptions introduced in the closure formulations may result in potential sources of structural uncertainty that can affect the quantities of interest (QoI), especially in multi-physics phenomena, e.g., combustion processes and interfacial... Read More

Bio:
Dr. Lluis Jofre is a Postdoctoral Fellow at the Center for Turbulence Research (CTR) at Stanford University. He graduated from Polytechnic University of Catalonia (Spain) in conjunction with KTH -... Read More
Tea Seminar : Friday, February 9, 2018 - 4:30pm : Speaker(s): Dr. Michael S. Dodd
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A set of governing equations to describe gas-liquid flows with phase change in the low Mach number limit will be presented. The system of equations accommodates local volume change at the gas-liquid interface due to condensation and evaporation while the total volume of the gas-liquid mixture remains constant. The framework is useful for simulating flows in computational domains that only use combinations of periodic and wall boundary conditions (e.g., isotropic turbulence and turbulent channel flow). Also, compared to the fully compressible formulation, this approach has the advantage of r... Read More

Bio:
Dr. Michael Dodd is a Postdoctoral Fellow at the Center for Turbulence Research at Stanford University. Dodd received his Bachelor’s degree in Aerospace Engineering from the University of Michigan in... Read More
Tea Seminar : Friday, January 26, 2018 - 4:30pm : Speaker(s): Dr.-Ing. Lin Fu
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A family of high order TENO (targeted ENO) schemes has been proposed by Fu et al. [JCP 305 (2016): 333-359] [JCP 349 (2017): 97-121]. In this talk, the key concept of TENO schemes and the differences between TENO and WENO will be addressed, as well as the framework to construct arbitrarily high-order TENO reconstruction. Then, he will introduce the method to optimize and control numerical dispersion and dissipation separately. Thirdly, the TENO schemes capable of capturing shocks and resolving incompressible and compressible turbulence as an implicit LES model will be outlined. At last, he... Read More

Bio:
Dr.-Ing. Lin Fu is a postdoctoral fellow of CTR at Stanford University. Before he joined CTR, he did postdoctoral research with Professor N.A. Adams in Technical University of Munich. In the same... Read More

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