Artículo de revista
Enhancement of synthetic schlieren image resolution using total variation optical flow: application to thermal experiments in a Hele‑Shaw cell
Fecha
2016Registro en:
Exp Fluids (2016) 57:18
0723-4864
DOI: 10.1007/s00348-015-2109-1
Autor
Letelier, Juvenal
Herrera Ricci, Paulo
Mujica Fernández, Nicolás
Ortega Palma, Jaime
Institución
Resumen
We present an improvement to the standard
synthetic schlieren technique to obtain the temperature
distribution of a fluid inside of a Hele-Shaw cell. We aim
to use the total variation L1-norm optical flow method to
treat experimental images and to obtain quantitative results
of the development of thermal convection inside a cell, by
detecting the gradients of the optical refractive index. We
present a simple algorithm to set the optical flow parameters,
which is based on the comparison between the optical
flow output and the result obtained by digital PIV using the
structural index metric. As an example of the application of
the proposed method, we analyze laboratory experiments
of thermal convection in porous media using a Hele-Shaw
cell. We demonstrate that the application of the proposed
method produces important improvements versus digital
PIV, for the quantification of the gradients of the refractive
index including the detection of small-scale convective structures. In comparison with correlation-based digital
methods, we demonstrate the advantages of the proposed
method, such as denoising and edge capture. These features
allow us to obtain the temperature, for this experimental
setting, with better image resolution than other techniques
reported in the literature.