title: Assessment of some experimental and image analysis factors for background-oriented schlieren measurements.
abstract: Quantitative measurements of fluid flow properties can be achieved by background-oriented schlieren (BOS). In this paper, it is shown that this depends on several factors. Image-quality index is used to investigate the influence of the image sensor and the quality of its output. Image evaluation is applied to synthetic images, which are treated with a step function, so that they simulate the sharp density jump. The gradual change of the evaluated vector shift revealed the major dependence on the interrogation window, and revealed less of a dependence on background features. BOS applied to shock-wave reflection from a wedge in a shock tube gave qualitative results, due to large uncertainties. But, the application to cooling by natural convection gave satisfactory results, comparable to thermocouple data and theory.
authors.affiliation: Institute of Fluid Science, Tohoku University, Katahira, Aoba, Sendai, Japan. gojani@edge.ifs.tohoku.ac.jp
authors.forename: Ardian B
authors.initials: AB
authors.lastname: Gojani
authors.forename: Shigeru
authors.initials: S
authors.lastname: Obayashi