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Lookup NU author(s): Dr Celine GuervillyORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Accurate measurement of fluid velocity remains a significant challenge in experimental fluid dynamics, as it requires capturing detailed spatial and temporal information within flows that are frequently turbulent. Obtaining velocity fields requires tracking identifiable features within the flow, such as particles, tracer elements, or coherent flow structures, over time. This typically requires accurate optical visualization of the flow. The most prevalent and effective method for measuring fluid velocity in the laboratory is particle image velocimetry (PIV), which uses the tracking of suspended reflective or fluorescent particles to determine the fluid's velocity. The mathematical method commonly used to track particles is the cross-correlation between two images. PIV relies on a laser sheet to illuminate the particles in a plane and requires the fluid to be transparent to visible light. To overcome these optical constraints, we propose to use the surface temperature field, which is accurately measurable in the context of thermal convection experiments. This provides structures that can be tracked if the temperature field is mainly advected by the flow. We employ the Farneback dense optical flow algorithm to track the features of the temperature field. Similar methods have proven effective in tracking planetary flows, as demonstrated by measuring Jupiter's surface or Earth's ocean currents. We present here a benchmark study using a simple, synthetic two-dimensional advection-diffusion simulation, as well as a rapidly rotating quasi-geostrophic simulation based on the "Coreaboloid" experimental setup. We investigate the applicability of thermal image velocimetry (TIV) to measuring the velocity field in rotating convection experiments. The reconstructed velocity field allows for a quantitative physical analysis of the flow dynamics.
Author(s): Monville R, Guervilly C, Cao H, Aurnou JM
Publication type: Article
Publication status: Published
Journal: APS Open Science
Year: 2026
Volume: 1
Online publication date: 03/08/2026
Acceptance date: 18/06/2026
Date deposited: 10/08/2026
ISSN (electronic): 3070-2240
Publisher: American Physical Society
URL: https://doi.org/10.1103/1jkc-jrq8
DOI: 10.1103/1jkc-jrq8
Data Access Statement: Some of the data that support the findings of this article are openly available (TIV package including an example notebook [38], advection-diffusion code [46]). Quasigeostrophic and advection-diffusion code raw output are not publicly available upon publication because it is not technically feasible and/or the cost of preparing, depositing, and hosting the data would be prohibitive within the terms of this research project. The data are available from the authors upon reasonable request.
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