Directeur de Recherche
Équipe de Recherche : Turbulence & Instabilités
tél : 04.72.18.62.04
email
Research Activities
Toms riddle for drag-reduction by polymers
 Article dans J. Fluid Mech. (2025) The Role of Vortex Stretching in Drag Reduction of Polymer-Laden Turbulent FlowWouter J. T. Bos, Xuan Shao, Tong Wu & Le Fang
An addition of polymers can significantly reduce drag in wall-bounded turbulent flows, such as pipes or channels. This phenomenon is accompanied by a noticeable modification of the mean velocity (...) |
Inhomogeneous turbulence
Honourable Mention for Emerging Scholar Best Paper Prize for JFM
 Article dans J. Fluid Mech. (2024) Inertial range scaling of inhomogeneous turbulenceRyo Araki & Wouter Bos
We investigate how inhomogeneity influences the $k^−5/3$ inertial range scaling of turbulent kinetic energy spectra (with 𝑘 the wavenumber). For weak statistical inhomogeneity, the energy spectrum (...) |
Temporal Fluctuations in turbulence : the origin of quasi-periodic motion
Highlights of 2023 of Fluid Dynamics Research
 Article dans Fluid Dyn. Res. (2023) Minimal model of quasi-cyclic behaviour in turbulence driven by Taylor–Green forcingRyo Araki, Wouter Bos & Susumu Goto
We attempt to formulate the simplest possible model mimicking turbulent dynamics, such as quasi-cyclic behaviour (QCB), using only three variables. To this end, we first conduct direct numerical (...) |
Two-dimensional turbulence
 Article dans Phys. Rev. Fluids (2024) Influence of the vorticity-scalar correlation on mixingXi-Yuan Yin, Wesley Agoua, Tong Wu & Wouter J. T. Bos
Many factors influence the long-time behavior and mixing of a passive scalar field transported by a two-dimensional (2D) fluid flow. Our investigations based on statistical mechanics and (...) |
 Article dans Phys. Rev. Fluids (2025) Coexistence of two equilibrium configurations in 2D turbulence.Wesley Agoua, Xi-Yuan (Bruce) Yin, Tong Wu and Wouter J.T. Bos
In two-dimensional flows, coherent structures often coexist with a turbulent background. We demonstrate that a large-scale dipole can be distinguished from turbulent noise by considering it as an (...) |
The fluid mechanics of the LH transition in tokamaks
 Article dans J. Fluid Mech. (2024) A critical transition of two-dimensional flow in toroidal geometryWesley Agoua, Benjamin Favier, Jorge Morales and Wouter J.T. Bos
We investigate two-dimensional (2-D) axisymmetric flow in toroidal geometry, with a focus on a transition between 2-D three-component flow and 2-D two-component flow. This latter flow state (...) |
Space-local turbulence
 Article dans Phys. Rev. Fluids (2024) Space-local Navier–Stokes turbulenceRyo Araki, Wouter Bos & Susumu Goto
We investigate the physical-space locality of interactions in three-dimensional incompressible turbulent flow. To that, we modify the nonlinear terms of the vorticity equation such that the (...) |
Grid-turbulence and very long length scales
 Article dans J. Turbul. (2024) Exciting turbulence in an elongated domainTong Wu, Le Fang, Joachim Peinke & Wouter Bos
Motivated by recent experimental results in grid turbulence with very long streamwise velocity correlations, we consider numerical simulations of turbulence in a domain that is elongated in one (...) | |
 Article dans Phys. Rev. Fluids (2020) Production and dissipation of kinetic energy in grid turbulenceWouter Bos
In grid turbulence, not so far behind the grid, an average flow can be observed with a close to sinusoidal velocity profile, corresponding to the wakes behind the grid bars. The kinetic energy of (...) |
 Article dans Phys. Rev. Letters (2020) Generation of Atmospheric Turbulence with Unprecedentedly Large Reynolds Number in a Wind TunnelLars Neuhaus, Michael Hölling, Wouter Bos & Joachim Peinke
Generating laboratory flows resembling atmospheric turbulence is of prime importance to study the effect of wind fluctuations on objects such as buildings, vehicles, or wind turbines. A novel (...) |
Turbulence without vortex-stretching
 Article dans Phys. Rev. Fluids (2022) Cascades of enstrophy and helicity in turbulence without vortex stretchingTong Wu & Wouter Bos
We consider three-dimensional turbulence from which vortex stretching is removed. Using direct numerical simulations, we show that in this system a dual cascade is observed, consisting of a (...) |
 Article dans J. Stat. Mech. (2023) Point-vortex statistical mechanics applied to turbulence without vortex stretchingTong Wu, Tomos David & Wouter Bos
In turbulent systems with inverse cascades, energy will pile up at large scales if no large-scale sink is present. We observe that in forced-dissipative three-dimensional turbulence from which (...) |
 Article dans J. Fluid Mech. (2021) Statistical mechanics of the Euler equations without vortex stretchingTong Wu & Wouter Bos
We consider the relaxation to thermal equilibrium of the Galerkin-truncated Euler equations in three dimensions, from which vortex stretching is removed. We prove that helicity and enstrophy are (...) |
 Article dans J. Fluid Mech. (2021) Three-dimensional turbulence without vortex stretchingWouter Bos
We consider three-dimensional turbulence from which vortex stretching is removed. The resulting system conserves enstrophy, but does not conserve kinetic energy. Using spectral closure, it is (...) |
Modeling the epidemic
 Article dans Phys. Rev. E (2023) Periodic epidemic outbursts explained by local saturation of clustersLouis Gostiaux, Wouter Bos & Jean-Pierre Bertoglio
Adding the notion of spatial locality to the susceptible-infected-recovered (or SIR) model, allows to capture local saturation of an epidemic. The resulting minimum model of an epidemic, (...) |
 Article dans Comput. Mech. (2021) Modeling the role of clusters and diffusion in the evolution of COVID-19 infections during lock-downWouter Bos, Jean-Pierre Bertoglio & Louis Gostiaux
The dynamics of the spread of epidemics, such as the recent outbreak of the SARS-CoV-2 virus, is highly nonlinear and therefore difficult to predict. As time evolves in the present pandemic, it (...) |
Turbulence and equilibrium
 Article dans J. Turbul. (2023) An EDQNM study of the dissipation rate in isotropic non-equilibrium turbulenceLe Fang and Wouter Bos
The energy cascade from large to small scales is a robust feature of three-dimensional turbulence. In statistically steady turbulence, the average dissipation is in equilibrium with the energy (...) |
 Article dans Phys. Rev. Fluids (2017) Dissipation in unsteady turbulenceWouter J.T. Bos, Robert Rubinstein
Recent experiments and simulations have shown that unsteady turbulent flows display a universal behavior at short and intermediate times, different from classical scaling relations. The origin of (...) |
Birth of helicity
 Article dans Phys. Rev. E (2021) Spontaneous generation and reversal of helicity in anisotropic turbulenceWesley Agoua, Benjamin Favier, Alexandre Delache, Antoine Briard & Wouter Bos
Helicity plays an important role in spectacular geophysical phenomena such as hurricanes or the generation of the terrestrial magnetic field. The present investigation shows how helicity can be (...) |
ANR project CM2E
 ANR Project 2021-2025
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MHD and The Fluid Mechanics of Fusion Plasmas
 Wouter Bos raconte ITER à RCF15 septembre 2020
Wouter Bos a été interviewé par la radio lyonnaise RCF pour parler du projet ITER, International Thermonuclear Experimental Reactor. Ce programme a l’ambition de construire le plus grand tokamak (...) | |
 Article dans Phys. Plasmas (2022) The dynamo properties of the reversed field pinch velocity fieldRobert Chahine, Wouter J. T. Bos & Nicolas Plihon
Reversed field pinch (RFP) is a toroidal device aiming at magnetic confinement of a plasma in order to reach conditions of thermonuclear reactions. In RFPs, the magnetic and velocity fields (...) |
 Article dans J. Plasma Phys. (2021) Effect of shaping on turbulent dynamics in reversed-field pinch simulationsRobert Chahine, Kai Schneider & Wouter Bos
We study the influence of the shape of the plasma container on the dynamics of the reversed-field pinch (RFP). The geometries we consider are periodic cylinders with elliptical and (...) |
 Article dans Phys. Rev. Fluids (2020) Scaling laws in axisymmetric magnetohydrodynamic duct flowsAlexandre Poyé, Olivier Agullo, Nicolas Plihon, Wouter Bos, Victor Desangles & Guillaume Bousselin
We report on a numerical study of axisymmetric flow of liquid metal in a circular duct with a rectangular cross section. The flow is forced through the combination of an axial magnetic field and (...) |
 Article dans Fluid Dyn. Res. (2014) Self-organization of helically forced MHD flow in confined cylindrical geometriesMalcolm Roberts, Matthieu Leroy, Jorge Morales, Wouter Bos & Kai Schneider
The dynamics of a magnetically forced conducting fluid in confined geometries is studied. A pseudospectral method with volume penalisation is used to solve the resistive magnetohydrodynamic (...) |
 Article dans Plasma Phys. Control. Fusion (2014) The effect of toroidicity on reversed field pinch dynamicsJorge A. Morales, Wouter J. T. Bos, Kai Schneider & David C. Montgomery
The influence of the curvature of the imposed magnetic field on reversed field pinch dynamics is investigated by comparing the flow of a magnetofluid in a torus with aspect ratio 1.83, with the (...) |
 Article dans J. Comput. Phys. (2014) Simulation of confined magnetohydrodynamic flows with Dirichlet boundary conditions using a pseudo-spectral method with volume penalizationJorge A.Morales, Matthieu Leroy, Wouter J. T. Bos & Kai Schneider
A volume penalization approach to simulate magnetohydrodynamic (MHD) flows in confined domains is presented. Here the incompressible visco-resistive MHD equations are solved using parallel (...) |
 Article dans J. Plasma Phys. (2015) Flow dynamics and magnetic induction in the von-Kármán plasma experimentN. Plihon, G. Bousselin, F. Palermo, J. Morales, W. J. T. Bos, F. Godeferd, M. Bourgoin, J.-F. Pinton, M. Moulin & A. Aanesland
The von-Kármán plasma experiment is a novel versatile experimental device designed to explore the dynamics of basic magnetic induction processes and the dynamics of flows driven in weakly (...) |
 Article dans Phys. Plasmas (2015) Magnetohydrodynamically generated velocities in confined plasmaJorge A. Morales, Wouter J. T. Bos, Kai Schneider & David C. Montgomery
We investigate by numerical simulation the rotational flows in a toroid confining a conducting magnetofluid in which a current is driven by the application of externally supported electric and (...) |
 Article dans Phys. Plasmas (2015) Dynamic equilibria and magnetohydrodynamic instabilities in toroidal plasmas with non-uniform transport coefficientsShimpei Futatani, Jorge A. Morales & Wouter J. T. Bos
It can be shown that in the presence of a toroidal magnetic field induced by poloidal coils, combined with the electromagnetic field induced by a central solenoid, no static equilibrium is (...) |
 Article dans Phys. Plasmas (2018) On the role and value of $\beta$ in incompressible MHD simulationsRobert Chahine & Wouter J. T. Bos
The parameter $\beta$, defined as the ratio of the pressure to the square of the magnetic field, is widely used to characterize astrophysical and fusion plasmas. However, in the dynamics of a (...) |
Physics of sports
 Article dans Phys. Rev. Fluids (2017) Directional change of fluid particles in two-dimensional turbulence and of football playersBenjamin Kadoch, Wouter J. T. Bos, and Kai Schneider
Multiscale directional statistics are investigated in two-dimensional incompressible turbulence. It is shown that the short-time behavior of the mean angle of directional change of fluid (...) | |
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 In the media
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Critical transitions in turbulent flows
 Article dans J. Turbulence (2021) Transition from axisymmetric to three-dimensional turbulenceZecong Qin, Aurore Naso & Wouter Bos
In purely axisymmetric turbulence sustained by a linear forcing mechanism, a stable, entirely poloidal flow is observed when the toroidal component of the forcing is below a threshold. We (...) | |
 Article dans Phys. Rev. E (2020) Linearly forced isotropic turbulence at low Reynolds numbersWouter Bos, Faouzi Laadhari & Wesley Agoua
The forcing strength needed to sustain a flow using linear forcing is investigated. A critical Reynolds number $R_c$ is determined, based on the longest wavelength allowed by the system, the (...) |
 Article dans Phys. Rev. Fluids (2020) Transition from non-swirling to swirling axisymmetric turbulenceZecong Qin, Hugues Faller, Bérengère Dubrulle, Aurore Naso & Wouter Bos
Strictly axisymmetric turbulence, i.e., turbulence governed by the Navier-Stokes equations modified such that the flow is invariant in the azimuthal direction, is a system intermediate between (...) |
Mixing of passive scalars and viscous heating
 Article dans Phys. Rev. E (2020) Efficiency of laminar and turbulent mixing in wall-bounded flowsBenjamin Kadoch, Wouter Bos & Kai Schneider
A turbulent flow mixes in general more rapidly a passive scalar than a laminar flow does. From an energetic point of view, for statistically homogeneous or periodic flows, the laminar regime is (...) |
 Article dans Fluid Dyn. Res. (2019) Passive scalar mixing in modulated turbulenceYuyao Yang, Robert Chahine, Robert Rubinstein & Wouter JT Bos
We investigate the mixing of a passive scalar in an isotropic turbulent flow in the presence of a time-periodic forcing. The results corroborate recent analytical predictions on the frequency (...) |
 Article dans J. Fluid Mech. (2014) The temperature spectrum generated by frictional heating in isotropic turbulenceWouter J. T. Bos
In every turbulent flow with non-zero viscosity, heat is generated by viscous friction. This heat is then mixed by the velocity field. We consider how heat fluctuations generated in this way are (...) |
 Article dans J. Fluid Mech. (2014) On the anisotropy of the turbulent passive scalar in the presence of a mean scalar gradientWouter J. T. Bos
We investigate the origin of the scalar gradient skewness in isotropic turbulence on which a mean scalar gradient is imposed. The problem of the advection of an anisotropic scalar field is (...) |
 Article dans Phys. Rev. E (2015) Dependence of turbulent advection on the Lagrangian correlation timeWouter J. T. Bos & Le Fang
In turbulent scalar mixing, starting from random initial conditions, the root-mean-square advection term rapidly drops as the flow and the scalar field organize. We show first analytically, for (...) |
 Article dans Phys. Fluids (2015) On the scaling of temperature fluctuations induced by frictional heatingWouter J. T. Bos, Robert Chahine & Andrey V. Pushkarev
The temperature fluctuations generated by viscous dissipation in an isotropic turbulent flow are studied using direct numerical simulation. It is shown that their scaling with Reynolds number is (...) |
 Article dans Comput. Fluids (2017) Mixing in modulated turbulence. Analytical resultsWouter J.T. Bos, Robert Rubinstein
Recent numerical results show that if a scalar is mixed by periodically forced turbulence, the average mixing rate is directly affected for forcing frequencies small compared to the integral (...) |
 Article dans Phys. Rev. Fluids (2017) Reynolds and Prandtl number scaling of viscous heating in isotropic turbulenceAndrey Pushkarev, Guillaume Balarac, and Wouter J. T. Bos
Viscous heating is investigated using high-resolution direct numerical simulations. Scaling relations are derived and verified for different values of the Reynolds and Prandtl numbers. The (...) |
Power fluctuations
 Article dans Phys. Rev. letters (2019) Power fluctuations in turbulenceWouter J. T. Bos & Rémi Zamansky
To generate or maintain a turbulent flow, one needs to introduce kinetic energy. This energy injection necessarily fluctuates and these power fluctuations act on all turbulent excited length (...) |
 Un article LMFA en couverture de PRLPower fluctuations in turbulence [with Rémi Zamansky (IMFT)]
How universal are the power-fluctuations measured in the electricity output of a windmill ? Indeed, the power fluctuation experienced by a windmill blade are determined by the power absorbed by (...) |
Lagrangian dynamics of turbulence
 Article dans Phys. Rev. letters (2015) Angular statistics of Lagrangian trajectories in turbulenceWouter J. T. Bos, Benjamin Kadoch & Kai Schneider
The angle between subsequent particle displacement increments is evaluated as a function of the time lag in isotropic turbulence. It is shown that the evolution of this angle contains two (...) |
 Article dans Phys. Fluids (2015) Short-time evolution of Lagrangian velocity gradient correlations in isotropic turbulenceLe Fang, Wouter J. T. Bos & Guodong D. Jin
We show by direct numerical simulation (DNS) that the Lagrangian cross correlation of velocity gradients in homogeneous isotropic turbulence increases at short times, whereas its auto-correlation (...) |
 Article dans Phys. Plasmas (2022) Lagrangian conditional statistics and flow topology in edge plasma turbulenceBenjamin Kadoch, Diego del-Castillo-Negrete, Wouter J. T. Bos & Kai Schneider
Lagrangian statistics and particle transport in edge plasma turbulence are investigated using the Hasegawa–Wakatani model and its modified version. The latter shows the emergence of pronounced (...) | |
Axisymmetric Turbulence
 Article dans Phys. Rev. Fluids (2018) Cascades of energy and helicity in axisymmetric turbulenceBo Qu, Aurore Naso, & Wouter J. T. Bos
A spectral analysis of strictly axisymmetric turbulence is performed. Both freely decaying and statistically steady flows are considered. In helical flows we identify a dual cascade, where energy (...) |
 Article dans Phys. Rev. Fluids (2017) Direct numerical simulation of axisymmetric turbulenceBo Qu, Wouter J. T. Bos, and Aurore Naso
The dynamics of decaying, strictly axisymmetric, incompressible turbulence is investigated using direct numerical simulations. It is found that the angular momentum is a robust invariant of the (...) |
Active Turbulence
 Article dans Phys. Rev. Fluids (2018) Turbulence and turbulent pattern formation in a minimal model for active fluidsMartin James, Wouter J. T. Bos, and Michael Wilczek
Active matter systems display a fascinating range of dynamical states, including stationary patterns and turbulent phases. While the former can be tackled with methods from the field of pattern (...) |
Depletion of nonlinearity
 Article dans Phys. Fluids (2014) Depletion of nonlinearity in two-dimensional turbulenceAndrey V. Pushkarev & Wouter J. T. Bos
The strength of the nonlinearity is measured in decaying two-dimensional turbulence, by comparing its value to that found in a Gaussian field. It is shown how the nonlinearity drops following a (...) |
Visco-elastic turbulence
 Article dans Phys. Rev. Fluids (2016) Small scale dynamics of isotropic viscoelastic turbulenceMin Quan Nguyen, Alexandre Delache, Serge Simoëns, Wouter J. T. Bos & Mamoud El Hajem
The comparison of the results of direct numerical simulations of isotropic turbulence of Newtonian and viscoelastic fluid provides evidence that viscoelasticity modifies qualitatively the (...) |