M. Ghorbani, G. Alcan, M. Unel, D. Gozuacik, S. Ekici, H. Uvet, A. Sabanovic, A. Kosar
Experimental Thermal and Fluid Science, Volume 78, Pages 322–333
Publication date: November, 2016


Recent studies show the destructive effect of the energy released from the collapse of cavitation bubbles, which are generated in micro domains, on the targeted surfaces. The cavitation phenomenon occurs at low local pressures within flow restrictive elements and strongly affects fluid flow regimes inside microchannels which results in spray formation. Extended cavitation bubbles toward the outlet of the microchannel, droplet evolution, and spray breakup are among crucial mechanisms to be considered in spray structure. In this study, various spray structures under the effect of hydrodynamic cavitation were recorded using a high speed visualization system. Acquired images were analyzed and characterized using several image processing algorithms. In this regard, the fluid flow with ascending upstream pressures from 10 to 120 bar were passed through a microchannel with an inner diameter of 0.152 mm. The spray at the outlet of the microchannel was analyzed for these pressures in four different segments. Particle Shadow Sizing (PSS) imaging and several image processing techniques such as contrast stretching, thresholding and morphological operations were employed to identify the flow regimes in the separated segments. In addition, a vision based estimation technique that utilizes a Kalman filter was developed to estimate cone angle of the spray. Furthermore, classification of fluid flow regimes and morphological characteristics of the spray structure were outlined based on the cavitation number.


  • A complete system including generation of microscale cavitating flows was constructed.
  • High speed visualization and novel image based analysis of spray structure were performed.
  • High speed flow characterization and elimination of manual adjustments are the advantages of the proposed system.
  • The fluid flow was classified as discrete droplet flow, liquid jet, jet cavitation, bubbly flow and highly vaporous bubbly flow.
  • Obtained cone angle of multiphase flow was estimated through 3D Gaussian modeling and by employing a Kalman filter.


  • Cavitation
  • Cone angle
  • Kalman filter
  • Microchannel
  • Spray
  • Visualization


  title={Visualization of microscale cavitating flow regimes via particle shadow sizing imaging and vision based estimation of the cone angle},
  author={Ghorbani, Morteza and Alcan, Gokhan and Unel, Mustafa and Gozuacik, Devrim and Ekici, Sinan and Uvet, Huseyin and Sabanovic, Asif and Kosar, Ali},
  journal={Experimental Thermal and Fluid Science},