Publications
99 results found
Blesbois O, Chernyshenko SI, Touber E, et al., 2013, Pattern prediction by linear analysis of turbulent flow with drag reduction by wall oscillation, JOURNAL OF FLUID MECHANICS, Vol: 724, Pages: 607-641, ISSN: 0022-1120
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- Citations: 28
Chernyshenko S, 2013, Drag reduction by a solid wall emulating spanwise oscillations. Part 1
A new idea for turbulent skin-friction reduction is proposed, wherein theshape of the solid wall is designed to create the spanwise pressure gradientacting similarly to the well-known method of drag reduction by in-planespanwise wall motion. Estimates based on the assumption of similarity with dragreduction effect of in-plane wall motion suggest that drag reduction of about2.4% can be achieved in the flow past a wavy wall, with the crests forming anangle of about 38 degrees with the main flow direction, and the wave period inthe main flow direction equal to about 1500 wall units. The required height ofthe wall waves have to be adjusted to achieve the same intensity of thespanwise motion as that created by an in-plane moving wall of the samewavelength and with peak wall velocity equal to 2 wall units. Further researchis being conducted in order to determine this height. Suggestions are made forfurther research on confirming the feasibility of the proposed method and onoptimising the wall shape.
Mathis R, Marusic I, Chernyshenko SI, et al., 2013, Estimating wall-shear-stress fluctuations given an outer region input, Journal of Fluid Mechanics, Vol: 715, Pages: 163-180-163-180
Chernyshenko SI, Marusic I, Mathis R, 2012, Quasi-steady description of modulation effects in wall turbulence
A theoretical description of the phenomenon of modulation of near-wallturbulence by large scale structures is investigated. The description given issimple in that the effect of large-scale structures is limited to aquasi-steady response of the near-wall turbulence to slow large-scalefluctuations of the skin friction. The most natural and compact form ofexpressing this mechanism is given by the usual Reynolds-number-independentrepresentation of the total skin friction and velocity, scaled in wallvariables, where the mean quantities are replaced by large-scalelow-pass-filtered fluctuating components. The theory is rewritten in terms offuctuations via a universal mean velocity and random mean square fluctuationvelocity profiles of the small-scales and then linearised assuming that thelarge-scale fluctuations are small as compared to the mean components. Thisallows us to express the superposition and modulation coefficients of theempirical predictive models of the skin friction and streamwise fluctuatingvelocity given respectively by Marusic et al. (13th Eur. Turb. Conf., 2011) andMathis et al. (J. Fluid Mech. 2011, vol. 681, pp. 537-566). It is found thatthe theoretical quantities agree well with experimentally determinedcoefficients.
Goulart PJ, Chernyshenko S, 2012, Global stability analysis of fluid flows using sum-of-squares, PHYSICA D-NONLINEAR PHENOMENA, Vol: 241, Pages: 692-704, ISSN: 0167-2789
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- Citations: 38
Duque-Daza CA, Baig MF, Lockerby DA, et al., 2012, Modelling turbulent skin-friction control using linearized Navier–Stokes equations, Journal of Fluid Mechanics, Vol: 702, Pages: 403-414-403-414
Wang HL, Nikitin NV, Chernyshenko SI, 2011, Identification of a Laminar-Turbulent Interface in Partially Turbulent Flow, FLUID DYNAMICS, Vol: 46, Pages: 911-916, ISSN: 0015-4628
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- Citations: 1
Booker CD, Zhang X, Chernyshenko SI, 2011, Large-Scale Vortex Generation Modeling, JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 133, ISSN: 0098-2202
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- Citations: 3
Blesbois O, Chernyshenko SI, 2011, Generalised optimal perturbation approach applied to drag reduction by wall oscillations in turbulent flows
Drag reduction by wall oscillations in turbulent flows has recently been shown to be a promising technique. The reduction of the near wall streaks amplitude is known to play a significant role in the drag reduction mechanism. To gain a better understanding of the effect of wall oscillations on the streaks, the Generalised Optimal Perturbation (GOP) approach, based on the linearised Navier-Stokes equation, is used. Resemblance between drag and certain quantities arising in the GOP context is observed. It is found that for harmonic wall oscillations the streaks have an approximately constant angle to the main flow direction, with a jump in sign twice in the period. The mechanism of this phenomenon is clarified. The results are in a reasonable agreement with direct numerical simulations.
Daque CA, Baig MF, Lockerby DA, et al., 2011, Modelling turbulent skin-friction control using linearised Navier-Stokes equations, 13th European Turbulence Conference (ETC), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
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- Citations: 1
Sandoval M, Chernyshenko S, 2010, Extension of the Prandtl-Batchelor theorem to three-dimensional flows slowly varying in one direction, JOURNAL OF FLUID MECHANICS, Vol: 654, Pages: 351-361, ISSN: 0022-1120
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- Citations: 1
Goulart PJ, Chernyshenko SI, 2010, Stability analysis of fluid flows using sum-of-squares, Pages: 2971-2976
In this paper we present a new method for assessing the stability of finite-dimensional approximations to the Navier-Stokes equation for fluid flows. Approximations to the Navier-Stokes equation typically take the form of a set of linear ODEs with an additional bilinear term that conserves the total energy of the system state. We suggest a structured method for generating Lyapunov functions using sum-of-squares optimization that exploits this energy conservation property. We provide a numerical example demonstrating the use of this technique to assess the stability of a model of a shear flow between infinite parallel plates. © 2010 AACC.
Goulart PJ, Chernyshenko SI, 2010, Stability Analysis of Fluid Flows Using Sum-of-Squares, 2010 AMERICAN CONTROL CONFERENCE, Pages: 2971-2976, ISSN: 0743-1619
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- Citations: 2
Booker C, Zhang X, Chernyshenko S, 2009, Large-scale source term modeling of vortex generation, ISSN: 1048-5953
Methods of modeling vortex generation in computational fluid dynamics without mesh-ing the vortex generating device have been investigated. This is done by adding source terms to the governing equations to create vortices. Previous work in this area has focused on boundary layer control. This study looks at larger scale applications, such as using vortices for force enhancement. Two different approaches are tested. One is to model vortex generators directly, for which an existing method that replaces the force exerted on the fluid by a vortex generator with a source term is used. Also of this type, a simple im-mersed boundary method is used for comparison. The other approach uses source terms to create specified vortex velocity profiles. A method to add a continuous three-dimensional velocity is formulated and implemented in three ways; explicit calculation of the required forces from the Navier-Stokes equations, direct forcing (setting the velocity as boundary conditions), and penalty-type feedback forcing. After basic testing, all methods are applied in a practical engineering case using a commercial solver. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Nikitin N, Wang H, Chernyshenko S, 2009, Turbulent flow and heat transfer in eccentric annulus, JOURNAL OF FLUID MECHANICS, Vol: 638, Pages: 95-116, ISSN: 0022-1120
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- Citations: 24
Hetsch T, Savelsberg R, Chernyshenko SI, et al., 2009, Fast numerical evaluation of flow fields with vortex cells, EUROPEAN JOURNAL OF MECHANICS B-FLUIDS, Vol: 28, Pages: 660-669, ISSN: 0997-7546
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- Citations: 2
Donelli R, Iannelli P, Chernyshenko S, et al., 2009, Flow Models for a Vortex Cell, AIAA JOURNAL, Vol: 47, Pages: 451-467, ISSN: 0001-1452
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- Citations: 20
Booker C, Zhang X, Chernyshenko S, 2009, Large-scale source term modeling of vortex generation, ISSN: 1048-5953
Methods of modeling vortex generation in computational fluid dynamics without mesh-ing the vortex generating device have been investigated. This is done by adding source terms to the governing equations to create vortices. Previous work in this area has focused on boundary layer control. This study looks at larger scale applications, such as using vortices for force enhancement. Two different approaches are tested. One is to model vortex generators directly, for which an existing method that replaces the force exerted on the fluid by a vortex generator with a source term is used. Also of this type, a simple im-mersed boundary method is used for comparison. The other approach uses source terms to create specified vortex velocity profiles. A method to add a continuous three-dimensional velocity is formulated and implemented in three ways; explicit calculation of the required forces from the Navier-Stokes equations, direct forcing (setting the velocity as boundary conditions), and penalty-type feedback forcing. After basic testing, all methods are applied in a practical engineering case using a commercial solver. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Nikitin NV, Chernyshenko SI, Wang HL, 2009, Turbulent flow and heat transfer in eccentric annulus, Pages: 601-604
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- Citations: 2
Nikitin NV, Chernyshenko SI, Wang HL, 2009, Turbulent flow and heat transfer in eccentric annulus, 12th EUROMECH European Turbulence Conference, Publisher: SPRINGER-VERLAG BERLIN, Pages: 601-604, ISSN: 0930-8989
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- Citations: 2
Chernyshenko SI, Bondarenko ME, 2008, Master-modes in 3D turbulent channel flow, arXiv:0809.2896 [physics.flu-dyn]
Turbulent flow fields can be expanded into a series in a set of basic functions. The terms of such series are often called modes. A master- (or determining) mode set is a subset of these modes, the time history of which uniquely determines the time history of the entire turbulent flow provided that this flow is developed. In the present work the existence of the master-mode-set is demonstrated numerically for turbulent channel flow. The minimal size of a master-mode set and the rate of the process of the recovery of the entire flow from the master-mode set history are estimated. The velocity field corresponding to the minimal master-mode set is found to be a good approximation for mean velocity in the entire flow field. Mean characteristics involving velocity derivatives deviate in a very close vicinity to the wall, while master-mode two-point correlations exhibit unrealistic oscillations. This can be improved by using a larger than minimal master-mode set. The near-wall streaks are found to be contained in the velocity field corresponding to the minimal master-mode set, and the same is true at least for the large-scale part of the longitudinal vorticity structure. A database containing the time history of a master-mode set is demonstrated to be an efficient tool for investigating rare events in turbulent flows. In particular, a travelling-wave-like object was identified on the basis of the analysis of the database. Two master-mode-set databases of the time history of a turbulent channel flow were made available online. The services provided include the facility for the code uploaded by a user to be run on the server with an access to the data.
Chernyshenko SI, Constantin P, Robinson JC, et al., 2007, A posteriori regularity of the three-dimensional Navier-Stokes equations from numerical computations, JOURNAL OF MATHEMATICAL PHYSICS, Vol: 48, ISSN: 0022-2488
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- Citations: 32
Chernyshenko SI, Bondarenko ME, 2007, Master-mode set for 3D turbulent channel flow, 11th EUROMECH European Turbulence Conference, Publisher: SPRINGER-VERLAG BERLIN, Pages: 188-190, ISSN: 0930-8989
Chernyshenko SI, Di Cicca GM, Iollo A, et al., 2006, Analysis of Data on the Relation between Eddies and Streaky Structures in Turbulent Flows Using the Placebo Method, FLUID DYNAMICS, Vol: 41, Pages: 772-783, ISSN: 0015-4628
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- Citations: 4
Chernyshenko SI, Baig MF, 2005, The mechanism of streak formation in near-wall turbulence, JOURNAL OF FLUID MECHANICS, Vol: 544, Pages: 99-131, ISSN: 0022-1120
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- Citations: 85
Bondarenko ME, Chernyshenko SI, 2005, Master-modes of the 3D turbulent channel flow, American Physical Society, 58th Annual Meeting of the Division of Fluid Dynamics
Using Chebychev-Fourier representation of Direct Numerical Simulation solution we determine the so-called master modes, that is those modes which contain all essential information about the flow. The method used by E. Olson and E.S. Titi for 2D case is applied for 3D turbulent channel flow (i.e. Determining modes for continuous data assimilation in 2D turbulence, Journal of Statistical Physics, 113 (2003), 799-840). Initial simulation performed with 32786 Chebychev-Fourier modes using a spatial domain with streamwise and spanwise periods of 1.6 π revealed that the number of master-modes for Reτ=85 is N≤650. Number of master-modes is not the same as, but may be related to, the fractal dimension of the attractor. For the comparison, L. Keefe, J. Kim and P. Moin estimated the fractal dimension as Dλ=780 for Reτ=80. (i.e. The dimension of attractors underlying periodic turbulent Poiseuille flow, J. Fluid Mech (1992), vol. 242, pp.1-29). Results for higher Reτ will be obtained, analysed and reported at the conference. In particular we are interested in what organised structures will appear in the master modes
Chernyshenko SI, Baig MF, 2005, Streaks and vortices in near-wall turbulence, Workshop on New Developments and Application in Rapid Fluid Flows, Publisher: ROYAL SOC, Pages: 1097-1107, ISSN: 1364-503X
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- Citations: 14
Zannetti L, Chernyshenko SI, 2005, Vortex pair and Chaplygin cusps, EUROPEAN JOURNAL OF MECHANICS B-FLUIDS, Vol: 24, Pages: 328-337, ISSN: 0997-7546
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- Citations: 7
Bouferrouk A, Chernyshenko SI, 2005, Tikhonov regularisation in discrete vortex methods, COMPUTERS & FLUIDS, Vol: 34, Pages: 275-281, ISSN: 0045-7930
Baig MF, Chernyshenko SI, 2004, Regeneration mechanism of streaks in near-wall quasi-2D turbulence, EUROPEAN JOURNAL OF MECHANICS B-FLUIDS, Vol: 23, Pages: 727-736, ISSN: 0997-7546
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- Citations: 4
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