# Channel flows: Twente Water Tunnel (TWT) and Twente Mass and Heat transfer Tunnel (TMHT)

The Twente Water Tunnel is an 8m high facility in which strong turbulence (up to a Taylor-Reynolds number of 300) can be created using an active grid. Light particles including micro-bubbles, finite-sized bubbles, and hollow spheres can be suspended in the turbulent flow. The setup houses bubble injection islands capable of producing mono-disperse bubbles with a concentration up to 10%. In addition, the size of the mono-disperse bubbles can be varied. These light particles may be made to rise with or against the flow, and can be observed and followed in the measuring section for long-duration tracking. The instrumentation includes 3D Particle Tracking Velocimetry, hot-film anemometry, and optical probes. A traverse system enables the movement of the cameras and other devices with the operated mean flow.

The control parameters in the TWT are the density ratio between particles and water, the particle size and concentration, the particle Reynolds number and the Taylor Reynolds number. The questions that we address with the TWT facility are the Lagrangian particle dynamics in the flow and in particular particle clustering, velocity and acceleration statistics, effect of particles on spectra and collision rates, average rise/sink velocity of particles, further Lagrangian aspects, and finally also bubbly drag reduction.

The TWT is a unique facility to explore light particle regime of the phase space in particles in turbulence: relative particle density vs. Stokes number at different turbulence levels.

Below, a video of the micro-bubbles tracked using a Moving Camera-Particle Tracking Velocimetry.

**Info:**

**Researchers:** Pim Waasdorp, Peter Dung, Jelle Will, Sander Huisman, Chao Sun, Detlef Lohse

**Technical staff:** Gert-Wim Bruggert, Martin Bos, and numerous of people of TCO.

**Collaborators:** Hans Kuipers (FCRE-group U. Twente), J.F. Pinton (ENS Lyon), Federico Toschi (TU Eindhoven), ICTR International Collaboration for Turbulence Research.

**Embedding:** MESA+, JMBC, European Research Network on Turbulence, ICTR International Collaboration for Turbulence Research.

**Sponsors:** European Research Network on Turbulence, FOM, AkzoNobel, TataSteel, DSM, Shell, EuHIT

**Previous researchers:** Biljana Gvozdić, Elise Alméras, Varghese Mathai, Daniel Chehata Gómez, Julián Martínez Mercado, Judith Rensen, Vivek Nagendra Prakash, Jon Brons, Yoshi Tagawa

### Publications

Bubbly and Buoyant Particle–Laden Turbulent Flows[arΧiv] V. Mathai, D. Lohse, and C. Sun Annu. Rev. Condens. Matter Phys. **11**, 529–559 (2020)BibTeΧ |

Mixing induced by a bubble swarm rising through incident turbulence[arΧiv] E.O. Alméras, V. Mathai, C. Sun, and D. Lohse Int. J. Multiphase Flow **114**, 316 – 322 (2019)BibTeΧ |

Dispersion of Air Bubbles in Isotropic Turbulence[arΧiv] V. Mathai, S.G. Huisman, C. Sun, D. Lohse, and M. Bourgoin Phys. Rev. Lett. **121**, 054501 (2018)BibTeΧ |

Flutter to tumble transition of buoyant spheres triggered by rotational inertia changes[Open Access] V. Mathai, X. Zhu, C. Sun, and D. Lohse Nat. Commun. **9**, 1792 (2018)BibTeΧ |

Mass and Moment of Inertia Govern the Transition in the Dynamics and Wakes of Freely Rising and Falling Cylinders[arΧiv] V. Mathai, X. Zhu, C. Sun, and D. Lohse Phys. Rev. Lett. **119**, 054501 (2017)BibTeΧ See also: **Phys.Org. August 17, 2017** |

Experimental investigation of the turbulence induced by a bubble swarm rising within incident turbulence[arΧiv] E.O. Alméras, V. Mathai, D. Lohse, and C. Sun J. Fluid Mech. **825**, 1091–1112 (2017)BibTeΧ |

Microbubbles and Microparticles are not Faithful Tracers of Turbulent Acceleration[arΧiv] V. Mathai, E. Calzavarini, J. Brons, C. Sun, and D. Lohse Phys. Rev. Lett. **117**, 024501 (2016)BibTeΧ |

Translational and rotational dynamics of a large buoyant sphere in turbulence[arΧiv] V. Mathai, M.W.M. Neut, E.P. van der Poel, and C. Sun Exp. Fluids **57**, 1–10 (2016)BibTeΧ |

Wake-Driven Dynamics of Finite-Sized Buoyant Spheres in Turbulence[arΧiv] V. Mathai, V.N. Nagendra Prakash, J. Brons, C. Sun, and D. Lohse Phys. Rev. Lett. **115**, 124501 (2015)BibTeΧ See also: **supplemental material** |

Energy spectra in turbulent bubbly flows[arΧiv] V.N. Nagendra Prakash, J. Martínez Mercado, L. van Wijngaarden, F.E. Mancilla Ramos, Y. Tagawa, D. Lohse, and C. Sun J. Fluid Mech. **791**, 174–190 (2016)BibTeΧ |

The clustering morphology of freely rising deformable bubbles[arΧiv] Y. Tagawa, I. Roghair, V.N. Nagendra Prakash, M. van Sint-Annaland, J.A.M. Kuipers, C. Sun, and D. Lohse J. Fluid Mech. **721**, R2 (2013)BibTeΧ |

How gravity and size affect the acceleration statistics of bubbles in turbulence[arΧiv] V.N. Nagendra Prakash, Y. Tagawa, E. Calzavarini, J. Martínez Mercado, F. Toschi, D. Lohse, and C. Sun New J. Phys. **14**, 105017 (2012)BibTeΧ Featured in: **"Highlights of 2012 - New Journal of Physics (NJP) - Soft Matter and Biophysics** |

Lagrangian statistics of light particles in turbulence[arΧiv] J. Martínez Mercado, V.N. Nagendra Prakash, Y. Tagawa, C. Sun, and D. Lohse Phys. Fluids **24**, 055106 (2012)BibTeΧ |

Three-dimensional Lagrangian Voronoï analysis for clustering of particles and bubbles in turbulence[arΧiv] Y. Tagawa, J. Martínez Mercado, V.N. Nagendra Prakash, E. Calzavarini, C. Sun, and D. Lohse J. Fluid Mech. **693**, 201–215 (2012)BibTeΧ |

On bubble clustering and energy spectra in pseudo-turbulence[arΧiv] J. Martínez Mercado, D. Chehata Gómez, D.P.M. van Gils, C. Sun, and D. Lohse J. Fluid Mech. **650**, 287–306 (2010)BibTeΧ |

Evolution of energy in flow driven by rising bubbles[arΧiv] I. Mazzitelli and D. Lohse Phys. Rev. E **79**, 066317 (2009)BibTeΧ |

Particles go with the flow D. Lohse Phys. **1**, 18 (2008)BibTeΧ |

Dimensionality and morphology of particle and bubble clusters in turbulent flow[arΧiv] E. Calzavarini, M. Kerscher, D. Lohse, and F. Toschi J. Fluid Mech. **607**, 13–24 (2008)BibTeΧ |

Universal Intermittent Properties of Particle Trajectories in Highly Turbulent Flows A. Arnèodo, R. Benzi, J. Berg, L. Biferale, E. Bodenschatz, A. Busse, E. Calzavarini, B. Castaing, M. Cencini, L. Chevillard, R. Fisher, R. Grauer, H. Homann, D. Lamb, A.S. Lanotte, E. Lévèque, B. Lüthi, J. Mann, N. Mordant, W.C. Müller, S. Ott, N.T. Ouellette, J.F. Pinton, S.B. Pope, S.G. Roux, F. Toschi, H. Xu, and P.K. Yeung Phys. Rev. Lett. **100**, 254504 (2008)BibTeΧ |

Quantifying Turbulence-Induced Segregation of Inertial Particles[arΧiv] E. Calzavarini, M. Cencini, D. Lohse, and F. Toschi Phys. Rev. Lett. **101**, 084504 (2008)BibTeΧ |

Energy spectra in microbubbly turbulence T.H. van den Berg, S. Luther, and D. Lohse Phys. Fluids **18**, 038103 (2006)BibTeΧ |

Hot-film anemometry in bubbly flow I: bubble–probe interaction J. Rensen, S. Luther, J. de Vries, and D. Lohse Int. J. Multiphase Flow **31**, 285 – 301 (2005)BibTeΧ |

The effect of bubbles on developed turbulence J. Rensen, S. Luther, and D. Lohse J. Fluid Mech. **538**, 153–187 (2005)BibTeΧ |

On the relevance of the lift force in bubbly turbulence I. Mazzitelli, D. Lohse, and F. Toschi J. Fluid Mech. **488**, 283–313 (2003)BibTeΧ |

The effect of microbubbles on developed turbulence I. Mazzitelli, D. Lohse, and F. Toschi Phys. Fluids **15**, L5–L8 (2002)BibTeΧ |

Induced bubble shape oscillations and their impact on the rise velocity J. de Vries, S. Luther, and D. Lohse European Physical Journal B **29**, 503–509 (2002)BibTeΧ |