Optical flow estimation with subgrid model for study of turbulent flow

The objective of this thesis is to study the evolution of scalar field carried by a flow from a temporal image sequence. The estimation of the velocity field of turbulent flow is of major importance for understanding the physical phenomenon. Up to now the problem of turbulence is generally ignored in the flow equation of existing methods. An information given by image is discrete at pixel size. Depending on the turbulent rate of the flow, pixel and time resolutions may become too large to neglect the effect of sub-pixel small-scales on the pixel velocity field. For this, we propose a flow equation defined by a filtered concentration transport equation where a classic turbulent sub-grid eddy viscosity model is introduced in order to account for this effect. To formulate the problem, we use a Markovian approach. An unwarping multiresolution by pyramidal decomposition is proposed which reduces the number of operations on images. The optimization coupled with a multigrid approach allows to estimate the optimal 2D real velocity field. Our approach is tested on synthetic andreal image sequences (PIV laboratory experiment and remote sensing data of dust storm event) with high Reynolds number. Comparisons with existing approaches are very promising.

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Source https://theses.hal.science/tel-00674772
Author Cassisa, Cyril
Maintainer CCSD
Last Updated May 26, 2026, 14:13 (UTC)
Created May 26, 2026, 14:13 (UTC)
Identifier NNT: 2011ECDL0010
Language en
Rights https://about.hal.science/hal-authorisation-v1/
contributor Laboratoire de Mecanique des Fluides et d'Acoustique (LMFA) ; École Centrale de Lyon (ECL) ; Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon) ; Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
creator Cassisa, Cyril
date 2011-04-07T00:00:00
harvest_object_id bd43c983-cff1-4115-a49d-14cdfb185ccc
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2026-03-30T00:00:00
set_spec type:THESE