2021 Fiscal Year Final Research Report
Modulation of turbulence by droplet coalescence
| Project/Area Number |
20K22402
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
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| Research Institution | Okinawa Institute of Science and Technology Graduate University |
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Principal Investigator |
Rosti Marco Edoardo 沖縄科学技術大学院大学, 複雑流体・流動ユニット, 准教授 (80876227)
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| Project Period (FY) |
2020-09-11 – 2022-03-31
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| Keywords | Multiphase flows / Turbulence / Drops and bubbles |
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| Outline of Final Research Achievements |
The effect of coalescence on droplets suspensions has been investigate numerically in both laminar and turbulent flow conditions. In laminar flow conditions, I studied how the rheology of droplets is affected by coalescence when the carrier fluid is non-Newtonian. The effect of viscosity ratio among the two phases, shear-thinning and thickening, and elasticity have been tackled. In turbulent flow conditions, I studied the effect of coalescence in homogeneous isotropic turbulent flows, in homogeneous shear flows and in plane channel flows. In the first two, the effect of viscosity ratio and elasticity have been investigated, while in the latter the role of coalescence was singled out by preventing it and comparing the results to those from a case where this effect was allowed. In addition to the above analysis, I have worked on the numerical methods to simulate droplet laden system with different level of complexity, enabling the study of contact line dynamics and droplet evaporation.
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| Free Research Field |
Fluid Dynamics
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| Academic Significance and Societal Importance of the Research Achievements |
We showed that droplets provide a spectral shortcut, subtracting energy from the large scales and re-introducing it at smaller scales, and coalescence changes the scale at which the energy is re-introduced. In wall-bounded flows, the effect of coalescence is stronger due to droplet migration.
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