Multi-scale approach for analyzing convective heat transfer flow in background-oriented Schlieren technique

TL;DR

This paper presents a multi-scale processing approach combining Fourier and wavelet transforms to quantitatively analyze convective heat transfer using background-oriented schlieren imaging, providing detailed insights into heat flow phenomena.

Contribution

It introduces a novel multi-scale analysis method that enhances quantitative visualization of convective heat transfer in schlieren techniques.

Findings

Effective phase estimation from fringe patterns

Enhanced visualization of heat flow structures

Quantitative analysis of temperature-induced refractive index changes

Abstract

The paper introduces a multi-scale processing method for quantitative study and visualization of convective heat transfer using diffractive optical element based background-oriented schlieren technique. The method relies on robust estimation of phase encoded in the fringe pattern using windowed Fourier transform and subsequent multi-scale characterization of the obtained phase using continuous wavelet transform. As the phase is directly mapped to the refractive index fluctuations caused by the temperature gradients, the multi-scale inspection provides interesting insights about the underlying heat flow phenomenon. The performance of the proposed method is demonstrated for quantitative flow visualization.