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We build an ultra-high-speed imaging system based on the background-oriented schlieren (BOS) technique in order to capture a laser-induced underwater shock wave. This BOS technique is able to provide two-dimensional density-gradient field…

Fluid Dynamics · Physics 2015-03-20 Shota Yamamoto , Yoshiyuki Tagawa , Masaharu Kameda

This study aims to overcome the problems that existing background-oriented schlieren (BOS) techniques based on computed tomography (CT-BOS) face when measuring pressure fields of laser-induced underwater shock waves. To do this, it proposes…

Fluid Dynamics · Physics 2022-11-30 Sayaka Ichihara , Takaaki Shimazaki , Yoshiyuki Tagawa

A high-resolution background-oriented schlieren (BOS) technique, which utilizes a high-resolution camera and a microdot background pattern, is proposed and used to measure the pressure field of an underwater shock wave in a microtube. The…

Shock wave-droplet interactions have been receiving increasing attention due to their relevance in aviation fuel combustion and minimally invasive medical treatments, yet quantifying them experimentally remains a challenge. In this study,…

Fluid Dynamics · Physics 2026-03-24 Sayaka Ichihara , Samuele Fiorini , Yoshiyuki Tagawa , Outi Supponen

We report a new workflow for background-oriented schlieren (BOS), termed "physics-informed BOS," to extract density, velocity, and pressure fields from a pair of reference and distorted images. Our method uses a physics-informed neural…

Diffractive optical element based background oriented schlieren (BOS) is a popular technique for quantitative flow visualization. This technique relies on encoding spatial density variations of the test medium in the form of an optical…

Image and Video Processing · Electrical Eng. & Systems 2025-10-01 Viren S. Ram , Tullio de Rubeis , Dario Ambrosini , Rajshekhar Gannavarpu

In order to measure the large density-gradient fields of fluids such as underwater shock waves, we employed a fast Fourier demodulation called Fast Checkerboard Demodulation (FCD) method in Background Oriented Schlieren (BOS) technique. BOS…

Fluid Dynamics · Physics 2022-02-17 Takaaki Shimazaki , Sayaka Ichihara , Yoshiyuki Tagawa

Non-intrusive quantitative fluid density measurements methods are essential in stratified flow experiments. Digital imaging leads to synthetic Schlieren methods in which the variations of the index of refraction are reconstructed…

Fluid Dynamics · Physics 2015-11-11 Lilly Verso , Alex Liberzon

The paper introduces a method for studying flow dynamics using diffractive optical element based background-oriented schlieren (BOS). Our method relies on fringe demodulation using root multiple signal classification technique which…

Image and Video Processing · Electrical Eng. & Systems 2019-10-29 Jagadesh Ramaiah , Sreeprasad Ajithaprasad , Gannavarpu Rajshekhar , Dario Ambrosini

Quantitative measurements of fluid flow properties can be achieved by background oriented schlieren. In this paper it is shown that this depends on several factors. Image quality index is used to investigate the influence of the image…

Optics · Physics 2013-03-06 Ardian B. Gojani , Shigeru Obayashi

Background oriented schlieren (BOS) visualization technique is examined by means of optical geometry. Two most important results are the calculation of the sensitivity and spatial resolution of a BOS system, which allows for the…

Optics · Physics 2013-10-03 Ardian B. Gojani , Burim Kamishi , Shigeru Obayashi

Background-oriented schlieren (BOS) is a powerful technique for flow visualization. Nevertheless, the widespread dissemination of BOS is impeded by its dependence on scientific cameras, computing hardware, and dedicated analysis software.…

Human-Computer Interaction · Computer Science 2025-07-14 Diganta Rabha , Vimod Kumar , Akshay Kumar , Dinesh Saini , Manish Kumar

We report a novel "cone-ray" model of background-oriented schlieren (BOS) imaging that accounts for depth-of-field effects. Reconstructions of the density field performed with this model are far more robust to the blur associated with a…

We develop a framework for non-invasive volumetric indoor airflow estimation from a single viewpoint using background-oriented schlieren (BOS) measurements and physics-informed reconstruction. Our framework utilizes a light projector that…

Signal Processing · Electrical Eng. & Systems 2025-09-19 Arjun Teh , Wael H. Ali , Joshua Rapp , Hassan Mansour

The background-oriented Schlieren technique has emerged as a promising method for visualizing density gradients and performing quantitative measurements. However, an inherent constraint of BOS is the compromise between spatial resolution…

Fluid Dynamics · Physics 2025-09-08 Xiang Li , Muen Gao , Weiran Wang , Jiawei Li , Chong Pan , Jinjun Wang , Yuan Xiong

In this work, the spatiotemporal pressure field of MHz-focused ultrasound is measured using a background-oriented schlieren technique combined with fast checkerboard demodulation and vector tomography (VT-BOS). Hydrophones have been…

Fluid Dynamics · Physics 2024-11-01 Sayaka Ichihara , Masato Yamagishi , Yuta Kurashina , Masanori Ota , Yoshiyuki Tagawa

Tomographic background oriented schlieren (Tomo-BOS) imaging measures density or temperature fields in 3D using multiple camera BOS projections, and is particularly useful for instantaneous flow visualizations of complex fluid dynamics…

A Tomographic Background-Oriented Schlieren (TBOS) technique is developed to aid in the visualization of compressible flows. An experimental setup was devised around a sub-scale rocket nozzle, in which four cameras were set up in a circular…

Fluid Dynamics · Physics 2023-11-20 Joachim A. Bron , Woutijn J. Baars , Ferdinand F. J. Schrijer

We present an image generation methodology based on ray tracing that can be used to render realistic images of Particle Image Velocimetry (PIV) and Background Oriented Schlieren (BOS) experiments in the presence of density/refractive index…

Image and Video Processing · Electrical Eng. & Systems 2019-07-24 Lalit K. Rajendran , Sally P. M. Bane , Pavlos P. Vlachos

This paper proposes a novel particle image velocimetry (PIV) technique to generate an instantaneous two-dimensional velocity field for sediment-laden fluid based on the optical flow algorithm of ultrasound imaging. In this paper, an…

Image and Video Processing · Electrical Eng. & Systems 2021-12-01 Weiliang Tao , Yan Liu , Zhimin Ma , Wenbin Hu
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