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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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | Multiphase flows / Turbulence / Drops and bubbles / Droplet-Laden flows / Numerical simulations / Droplets / Bubbles / Fluid dynamics |
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| Outline of Research at the Start |
We will perform direct numerical simulations to understand the role of finite-size droplets coalescence on turbulent flows. To do so, we will use a volume of fluid method where the droplets coalescence can be controlled. To get a deeper understanding of how energy is redistributed in the flow, we will consider the governing equation for the energy spectrum and evaluate the contribution of each term at the different scales. By comparing the results obtained for cases with different coalescence efficiency, we will elucidate its role on the process.
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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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| 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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Report
(3 results)
Research Products
(12 results)
