2021 Fiscal Year Annual Research Report
Modulation of turbulence by droplet coalescence
| Project/Area Number |
20K22402
|
|---|
| Research Institution | Okinawa Institute of Science and Technology Graduate University |
|---|
Principal Investigator |
ロスティ マルコエドアルド 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)
|
|---|
| Project Period (FY) |
2020-09-11 – 2022-03-31
|
| Keywords | Droplet-Laden flows / Turbulence / Numerical simulations |
|---|
| Outline of Annual Research Achievements |
The effect of coalescence on dropelts 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 colaescence when the carrier fluid is non-Newtonian.
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 two former, the effect of viscosity ratio and elasticty 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.
The above studies showed that droplet coalescence has a general tendency of reducing the effective viscosity of the system, as well as reducing the backreaction of the flow, which results less disturbed by the presence of the dispersed phase. The scale-by-scale analysis showed that droplets provide a spectral shortcut, subtracting energy from the large scales and re-introducing it at smaller scales. Coalescence changes the scale of the dropelts and thus the scale at which the energy is re-introduced in the system. In the case of wall-bounded flows, the effect of coalescence is even more pronounced, due to the additional migration effects that are more pronounced when colascence is 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.
|
