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Interaction of Surface and Interfacial Waves Over Fluid Mud Bed

Aleebrahim Dehkordi, Mohammad Ali | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 56851 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Jamali, Mirmosadegh
  7. Abstract:
  8. Motivated by the role of interfacial instabilities in sediment resuspension, this paper provides quantitative measurements of the long-time behavior of the interfacial waves and the changes in vertical density during motion of a surface wave over a muddy bed. After an initial fluidization process, a 3D quasi-standing interfacial wave was observed at the interface as a result of a resonant wave interaction with the surface wave. In the process, the quasi-standing wave started growing exponentially at a rate of 0.052-0.081 1/s and then reached a maximum amplitude (kexpb=0.77-0.83). The interfacial wave then took a downward trend in the transition stage and approached a steady state (kexpbu=0.56-0.64). The decay rate of the interfacial wave in the transition stage was equal to the damping rate of the wave (0.011-0.017 1/s). Before the appearance of the interfacial wave, fluidization and upward entrainment of mud particles were responsible for the changes in the fluid density. After the resonant interaction resulted in the appearance of the interfacial wave, the vertical profile of sediment particles correlated with the interfacial wave amplitude. By the end of the experiments, the amount of entrained mud particles into the clear water was determined. The results illustrate that the final amplitude of the standing wave is an important parameter describing the level of mixing. Further, the obtained results confirmed that the sediment resuspension caused by the resonance mechanism was about 2 to 8 times greater than the upward entrainment caused by the shear stress mechanism. At the end of the present study, the Fourier spectral method was used to simulate the excitation and growth of the two and three-dimensional resonantly generated interfacial waves. The numerical results were compared against the results obtained from the perturbation analysis, and a maximum difference of 17 % was observed between the results
  9. Keywords:
  10. Sloshing ; Internal Waves ; Nonlinear Resonance Interaction ; Spectral Method ; Mixing ; Fluid Mud

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