10 research outputs found
Deformation and Breakup of Finite-sized Bubbles in Intense Turbulence
From rain droplets in clouds to entrained gas bubbles in oceans, the majority of fluid mechanics problems in nature and industry are turbulent and consist of multiple phases. In such flows, bubbles and droplets experience complex deformation. Though this deformation occurs at small-scale interfaces, it plays important roles in many large-scale processes e.g. the overall heat and mass transfer in two-phase energy systems. To understand the fundamental physics behind the interaction between turbulence and deformable bubbles, simultaneous 3D measurements of both phases are essential. However, obtaining such measurements is a very challenging task. To address this problem, a unique vertical water tunnel (V-ONSET) capable of generating energetic turbulence is designed. V-ONSET is equipped with six high-speed cameras uniformly distributed around its test section to obtain high-resolution images of both bubbles and the turbulent carrier phase simultaneously. To reconstruct the 3D shapes of bubbles, a new algorithm addressing the limited-angle reconstruction problem by using the physical constraint of minimum surface energy is developed. Moreover, to quantify turbulence, tracer particles in the surrounding flow are tracked with an in-house OpenLPT code. Leveraging such unique simultaneous measurements of bubbles and their surrounding turbulent flow, we investigate the mechanisms in turbulence responsible for the deformation and breakup of bubbles. We identify and evaluate two key mechanisms namely, the coarse-grained turbulent strains and the slip velocity between the two phases. Interestingly, two Weber numbers based on these two mechanisms show that in strong turbulence, the rather ignored mechanism of the slip velocity has a comparable magnitude to the other mechanism of turbulent strains. The distributions of these two Weber numbers are modeled based on turbulent flow characteristics. This also helps to estimate bubble breakup probability in turbulence. Furthermore, we investigate the orientation dynamics of bubbles with respect to the aforementioned deformation mechanisms. It elucidates that bubbles exhibit the strongest alignment with the slip velocity direction indicating the dominant role played by the compression induced by the slip velocity. Finally, a Lagrangian model including both deformation mechanisms is proposed to predict bubble deformation and orientation in turbulence
Bibliography of Lewis Research Center technical publications announced in 1984
This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1984. All the publications were announced in the 1984 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses
Engineering Dynamics and Life Sciences
From Preface:
This is the fourteenth time when the conference “Dynamical Systems: Theory
and Applications” gathers a numerous group of outstanding scientists and engineers, who
deal with widely understood problems of theoretical and applied dynamics.
Organization of the conference would not have been possible without a great effort of
the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage
over the conference has been taken by the Committee of Mechanics of the Polish Academy
of Sciences and Ministry of Science and Higher Education of Poland.
It is a great pleasure that our invitation has been accepted by recording in the history
of our conference number of people, including good colleagues and friends as well as a large
group of researchers and scientists, who decided to participate in the conference for the
first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all
over the world. They decided to share the results of their research and many years
experiences in a discipline of dynamical systems by submitting many very interesting
papers.
This year, the DSTA Conference Proceedings were split into three volumes entitled
“Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical
Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and
Engineering Dynamics and Life Sciences. Additionally, there will be also published two
volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems
in Theoretical Perspective” and “Dynamical Systems in Applications”
11th International Coral Reef Symposium Abstracts
https://nsuworks.nova.edu/occ_icrs/1001/thumbnail.jp