Keiichi Sato’s research while affiliated with Kanazawa Institute of Technology and other places

... In a series of studies by the authors, detailed observations of laser-induced bubble formation and collapse have been conducted to determine the optimal conditions for applying impacts under laser irradiation. Measurements of the impact force, investigations into the relationship between temperature and impact for laser parameters, such as pulse duration and energy, observations of behavior in confined spaces using gelatin, and the influence of jets on the wall have been carried out (Sugimoto et al., 2017(Sugimoto et al., , 2018Moriyama et al., 2019;Hamamoto et al., 2019;Sugimoto and Hamamoto, 2020). ...

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Evaluation of thermal damage area of tissue around pulsed laser-induced bubbles in URS treatment based on CEM43

... Additionally, cavitation bubbles are more likely to be formed on the hydrophobic and rough surface, which is also called crevice model for nucleation [39,40]. The acoustic radiation forces on particles are much weaker than it on bubbles under the kHz-order USW [28,41]. According to this law, the aggregation could attribute to the behavior of the growth and coalescence of cavitation bubbles. ...

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Toward Efficient Interactions of Bubbles and Coal Particles Induced by Stable Cavitation Bubbles under 600 kHz Ultrasonic Standing Waves

... Further contraction leads to the fracture of the cavitation cloud at 2 t , then the shedding occurs. This process manifests as a re-entrant motion of the liquid near the nozzle, which periodically "pinches off" the cavitation cloud at the nozzle outlet (Peng et al., 2018;Sato et al., 2013;Sato et al., 2015). The profile of the potential core can be observed through the velocity distribution map and the iso-line of v  . ...

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On unsteady cavitation flow of a high-speed submerged water jet based on data-driven modal decomposition

... During this process cavitation bubbles are generated by injecting a highspeed water jet through a nozzle into a chamber filled with water. When the cavitation bubbles approach the surface of the material, the sudden increase of local pressure due to the huge turbulent pressure pulsation causes their collapsing which generates shock waves [19]. ese shock waves act on the surface of the workpiece and propagate into the interior of the workpiece, due to the high concentration of energy (the peak value of the collapse pressure reaches the gigapascal (GPa) range) [20]. ...

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Experimental Study on Water-Jet Shock Microforming Process Using Different Incident Pressures

... Further, Li et al. [15] investigated the impact of various geometric parameters on cavitation inception using a numerical simulation and experimental methods and discovered that flow resistance determines cavitation inception. Sato et al. [16] used a high-speed video camera to visualize the behavior of a moving bubble cavitation in a Venturi from the inception to collapse process. Brunhart et al. [17] verified two mechanisms of vapor shedding (re-entrant jet and condensation shock) and offered more information on vapor shedding using the computational fluid dynamics (CFDs) method. ...

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Numerical Investigation of the Cavitation Characteristics in Venturi Tubes: The Role of Converging and Diverging Sections

... As the cavitation cloud propagates downstream, new cavitation protrusions form at the cloud front 7 due to the shearing effect of the high-speed jet core 40 , while the upstream cavity vanishes due to lack of energy 8 replenishment from the jet core. Therefore, cloud collapse typically commences upstream, e.g., 11 reported the shedding mechanism triggered by shock waves. 14 However, due to the lower cav  , no obvious triggering of shock waves on shedding is observed in the present study. ...

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Experimental study on the unsteady behavior and frequency characteristics of high-speed submerged cavitating water jets

... These shock waves are generated at the moment of cavitation cloud collapse, and their formation range closely aligns with the erosion area of the cavitating jet on the wall material, indicating that shock wave formation plays a critical role in cavitation erosion. Countless bubbles form cavitation clouds, and the formation, growth and collapse of cavitation clouds is a periodic process, which has been verified in previous studies [30][31][32][33][34][35][36]. The shape of the cavitation cloud is often irregular and asymmetric. ...

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The Generation Methods and Applications of Cavitating Jet by Using Bubble Collapse Energy

... A frame difference method [17]- [19] is used to analyze the images obtained from a high-speed video observation, in which a gray level technique is applied, as shown in Figure 4. This method allows us to analyze and estimate the periodic behavior of cloud cavitation in various cavitating flow fields such as in a convergent-divergent test section [3] and a high-speed water jet [18] [19]. ...

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Unsteady Behavior of Cavitating Waterjet in an Axisymmetric Convergent-Divergent Nozzle: High Speed Observation and Image Analysis Based on Frame Difference Method

... In the case of a cavitating water jet, cloud cavitation is formed in the nozzle or at a nozzle exit and a jet boundary. There exist some severe pressure waves in the cloud region of the cavitating water jet Sato et al. 2009bSato et al. , c, 2013Saito and Sato 2007;Yoshida et al. 2012;Hutli et al. 2013b, c). Using the flow visualization techniques significantly improved the investigation and studying methods of cavitating flow, specifically in the analysis of cavitation conditions. ...

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Automatic Edge Detection Applied to Cavitating Flow Analysis: Cavitation Cloud Dynamics and Properties Measured through Detected Image Regions

... This is because the micro and nano bubbles produced by MAI carry significant surface negative ions, which move slowly in water, and can fully oxidize microorganisms when the bubbles burst [23]. However, the bubbles generated by VAI are prone to bubble aggregation with inconsistent gas output, and the oxygen dissolution efficiency is at a low level, which failed to produce enough oxidation effect on microorganisms [45,46]. At the same time, the cell membrane structure of Gram-negative bacteria is more complex than that of Grampositive bacteria [47], and the energy generated when micro and nano bubbles burst is not enough to damage the cell membrane structure. ...

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Effect of Aeration on Blockage Regularity and Microbial Diversity of Blockage Substance in Drip Irrigation Emitter