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A CRITERION FOR THE OCCURRENCE OF BUBBLE FISSION AND ITS MODELING

A CRITERION FOR THE OCCURRENCE OF BUBBLE FISSION AND ITS MODELING. Can F. D elale 1 , Şenay Pasinlioğlu 2 , Patrik Zima 3 1 I şık Universi ty, Istanbul , T urkey 2 Istanbul Technical University, Istanbul , T urkey 3 Institute of Thermomechanics, CAS, Prague, Czech Republic

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A CRITERION FOR THE OCCURRENCE OF BUBBLE FISSION AND ITS MODELING

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  1. A CRITERION FOR THE OCCURRENCE OF BUBBLE FISSION AND ITS MODELING Can F. Delale1, Şenay Pasinlioğlu2, Patrik Zima3 1Işık University, Istanbul, Turkey 2Istanbul Technical University, Istanbul, Turkey 3Institute of Thermomechanics, CAS, Prague, Czech Republic CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  2. CONTENTS • Bubble Dynamics and Energy Dissipation Mechanisms • 2. A Bubble Fission Model (Delale & Tunc, 2004) • New Criterion for Bubble Fission • Results • 4. Conclusions and Future Perspectives CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  3. 1. Bubble Dynamicsand Energy Dissipation Mechanisms Viscous Damping Thermal Damping Acoustic Damping Bubble Fission Free surface energy Mixing Turbulence Brennen CE (2002) J. Fluid Mech. 472, 153. CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  4. R Rmax1 Main Bubble Rmax2 Rmin Product Bubble rf t t1 t0 2. A bubble fission model Delale, Tunç (2004) Phys. Fluids 16, 4200-4203. Assumptions: • Bubble fission occurs at to , R=Rmin • The original volume is conserved • Pg remains the same during fission CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  5. RAYLEIGH-PLESSET EQUATION CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  6. 3. New Criterion for Bubble Fission Rayleigh-Taylor instability Transformation Seminar Presented at the Institute of Thermomechanics, Czech Academy of Sciences, Prague, 31August 2011

  7. The most unstable mode CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  8. Solve the initial value problem for the most unstable mode Break-up time where CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  9. Volume Conservation Energy Dissipation due to Bubble Fission CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  10. Initial Value Problem for Bubble Fragments CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  11. 4. Results Pressure Signal CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  12. Delale & Tunc (2004) Model (Nm=20,2) CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  13. Present Model (Nm=20,2) CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  14. Delale & Tunc (2004) Model (Nm=20,2) CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

  15. 5. Conclusions and Future Perspectives •The bubble fission model of Delale and Tunc (2004) is modified to shift the time break-time prior to the time at which the volume of the parent collapsing bubble attains its minimum value. •A bubble break-up criterion, based on Rayleigh-Taylor instability analysis, is established for the occurrence of bubble fission and the bubble break-up time is estimated. • The present model predicts more energy dissipation than that of Delale and Tunc (2004) as the number of fragments decrease. •Thermal damping effects and nonlinear Rayleigh-Taylor instability is reserved for future work . CAV2012 8th International Symposium on Cavitation, 14-16 August 2012, Singapore

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