title: Instrumented tracer for Lagrangian measurements in Rayleigh-Bénard convection.
abstract: We have developed novel instrumentation for making Lagrangian measurements of temperature in diverse fluid flows. A small neutrally buoyant capsule is equipped with on-board electronics which measures temperature and transmits the data via a wireless radio frequency link to a desktop computer. The device has 80 dB dynamic range, resolving millikelvin changes in temperature with up to 100 ms sampling time. The capabilities of these "smart particles" are demonstrated in turbulent thermal convection in water. We measure temperature variations as the particle is advected by the convective motion and analyze its statistics. Additional use of cameras allow us to track the particle position and to report here the first direct measurement of Lagrangian heat flux transfer in Rayleigh-Bénard convection. The device shows promise for opening new research in a broad variety of fluid systems.
authors.affiliation: Laboratoire de Physique de l'Ecole Normale Supérieure de Lyon, CNRS UMR5672, 46 allée d'Italie, F-69007 Lyon, France.
authors.forename: Woodrow L
authors.initials: WL
authors.lastname: Shew
authors.forename: Yoann
authors.initials: Y
authors.lastname: Gasteuil
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gibert
authors.forename: Pascal
authors.initials: P
authors.lastname: Metz
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Pinton
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008904:Miniaturization; D015203:Reproducibility of Results; D012212:Rheology / Q000295:instrumentation* / Q000379:methods; D012680:Sensitivity and Specificity; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods; D013814:Thermal Conductivity; D013817:Thermography / Q000295:instrumentation / Q000379:methods; D014159:Transducers