Clercx, H. J.H.

Del Castello, L.

Perlekar, P.

Toschi, F.

English

The effect of background rotation on the dispersion of (inertial) particles in confined forced rotating turbulence and in turbulent rotating convection has been studied and compared where possible. We choose the coordinate system such that both the rotation vector and gravity is parallel to the vertical axis. With 3D Particle Tracking Velocimetry experiments we have quantified statistically the effect of system rotation on the PDFs and autocorrelations of velocities and accelerations of (passive) fluid particles in rotating turbulence. Subsequently we have extended this study by exploring the effect of system rotation and buoyancy on the dispersion of passive and inertial particles in rotating thermally driven turbulence between two horizontal flat plates. The PDFs of horizontal and vertical accelerations of passive particles in turbulent rotating convection show similar behaviour as found in the laboratory experiments in isothermal forced rotating turbulence. When the particles have inertia it is observed that the particles tend to collect in anticyclonic regions of the flow eventually resulting in depletion of particles in the bulk of the flow (and accumulating near the top and bottom wall).</p

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 Lagrangian statistics of particles in rotating turbulentconvectionCitation for published version (APA):Clercx, H. J. H., Perlekar, P., Del Castello, L., & Toschi, F. (2020). Lagrangian statistics of particles in rotatingturbulent convection. Paper presented at 14th European Turbulence Conference, ETC 2013, Lyon, France.http://etc14.ens-lyon.fr/openconf/modules/request.php?module=oc_program&action=view.php&id=249Document status and date:Published: 01/01/2020Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. 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Oct. 2023                                                  14TH  EUROPEAN            LAGRANGIAN STATISTICS OF PARTICLES IN ROTATING TURBULENT CONVECTIONH.J.H. Clercx1Fluid Dynamics Laboratory and JM Burgers Center for Fluid Dynamics, Department of Applied Physics, Eindhoven University of Technology, The Netherlands Abstract The effect of background rotation on the dispersion of (inertial) particles in confined forced rotating turbulence and in turbulent rotating convection has been studiedrotation vector and gravity is parallel to the vertical axis. statistically the effect of system rotation on the PDFs and autocorrelations of in rotating turbulence. Subsequently we have dispersion of passive and inertial particles in rotating thermally driven turbulencehorizontal and vertical accelerations of passive particles in turbulent rotating convection show similar behavilaboratory experiments in isothermal forced rotating turbulence. When the particles have inertia it isob erved that the partto collect in anticyclonic regions of the flow eventually resulting in depnear the top and bottom wall).      The effect of background rotation on the dynamics of fluid flows is ubiquitous in largeastrophysical flows, as well as in the context of industrial rotating machinery. In many of these examples also buoyancy may play a crucial role. In this contribution we will discuss and compare Lagrangian data sets measured in (isothermal) forced rotating turbulence experiments and obtained by DNS of turbulent rotating convection. It is well-known that the Coriolis accelerationdynamics including anisotropisation of turbulent flows: 3D turbulent flows subject to fast background rotation evolves towards a quasi-2D state, which is characterised by a strong dadirection parallel to the rotation axis (and formation of vortex tubes parallel to the rotation axis). Based on Lagrangian measurements by 3D Particle Tracking Velocimetry of the velocity and acceleration of the rotating fluid, we have been able to quantify stati tically the effect of system rotation on the PDFs and autocorrelations of fluid particle velocity and acceleration in rotating turbulence for a range of dimensionless rotation rates (denoted by the Rossby numberscale in the turbulent flow and Ω the rotation ratecase [1,2]. Typical results will be discussedFigure 1. Horizontal (left) and vertical (right) acceleration PDFs of passive tracers a variety of rotation rates. The PDFs are based on 8x10skewness is observed for all rotation rates. The kurtosis K is generally large (K>10) excTURBULENCE CONFERENCE, 1-4 SEPTEMBER 2013, L 1, P. Perlekar1, L. Del Castello1 & F. Toschi1   an  compared where possible. We choose the coordinate system such that both the With 3D Particle Tracking Velocimetry experiments we have quantifievelocities and accelerations of (passive) extended this study by exploring the effect of system rotation  between two horizontal flat platesletion of particles in the bulk of the flowINTRODUCTION ROTATING TURBULENCE  term in the Navier-Stokes equations is responsible for altering the flow mping of velocity gradient components along the tiny solid particles embedded in , d fined as Ro=U/(2ΩL), with U and L the ty). The Rossby number will be as small as 0 and in particular the behaviour of the acceleration PDFs, see Figure 1            from experiments in forced rotating turbulence for 6 (horizontal velocity) and 4x106 (vertical velocity) data points. Hardly any ept for the highest rotation rate.YON, FRANCE      d fluid particles and buoyancy on the . The PDFs of our as found in the icles tend  (and accumulating -scale geophysical and  inverse pical velocity and length . 5 for the rapid rotation .   ROTATING THERMAL CONVECTIONParticle dispersion in buoyancy-driven rotating turbulence has been studied by DNS. We have used here a Lattice Boltzmann Method coupled with Lagrangian particle tracking algorithmparticles released in turbulent rotating Rayleighvertically confined. Both gravity and rotation are oriented in the vertical direction. Here we presentacceleration PDFs of particles in both nonthe bulk acceleration PDF in non-rotating RB turbulence is like in homogeneous isotropic turbulence whereas rotationintroduces anisotropy similar to the acceleration PDFs obtained from experiments in (isothermal) forced rotating turbulence [2]. We will discuss these PDFs and dispersion results for passive fluid elements and those obtained for inertial particles in rotating convection. When inertia starts to become important the Coriolis force should be included in the equations of motion of the particles according to the sketch in Figure 2. The Coriolis force introduces an additional compressibility mechanism for the particle velocities. It turns out that for flow time scale are similar in magnitude, cyclonic areas. This phenomenon is nicely illustrated in the middle and right panels of Figure 2. the effect of the Coriolis force for inertial particles in rotating turbulent co                  a)                                                             Figure 2. Numerical simulations of inertial particles with Stokes number of order unity in shallow fluid layers. particles are swept out of the vortical structures    Figure 3. Representative plot of the heavy particle distribution at the initial time and at later times rotating Rayleigh-Bénard convection (Ro=0.25). The presence of the Coriolis f rce leads to enhanced ejection of particles from regions of cyclonic vorticity but accumulation in the region of anticyclonic vorticity. These particles are th n transported towartop and bottom walls by the vertical velocity outside the cyclonic vertical vorticity tubes. The pseudopresence of vertical vorticity tubes. References       [1] L. Del Castello and H.J.H. Clercx, Phys. Rev. E     [2] L. Del Castello and H.J.H. Clercx, Phys. Rev. Lett.     [3] V. Lavezzo, H.J.H. Clercx, and F. Toschi, J. Phys.: Conf. Ser.   [3] to investigate the behaviour of (inertial) -Bénard (RB) convection. The flow domain is horizontally periodic and -r tating and strongly rotating RB convection (for Ro=0.25). It is found that Stokes number around unity, reflecting that particle relaxation time and typical inertial particles are depleted from cyclonic regions and accumulate in antinvection is shown in Figure 3.b)                                                   c) , and c) with system rotation particles prefer anticyclonic regions.     from numerical simulations  83: 056316 (2011).  107: 214502 (2011).  333: 012011 (2011).  the results of the  -The consequences of  b) Without rotation   in ds the -color plot indicates the 

Lagrangian statistics of particles in rotating turbulent convection

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Lagrangian statistics of particles in rotating turbulent convection

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