Soft Seminars
The role of particle-flow interactions in cloud microphysics
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Europe/Stockholm
Albano Building 3
Albano Building 3
Description
zoom link : https://stockholmuniversity.zoom.us/j/622224375
The collision of particles sedimenting in a flow field is
relevant to many environmental and industrial processes, such as droplet
growth in warm clouds and the aggregation of aerosol particles in
industrial settings. The evolution of the drop size distribution in
clouds depends on the collision rate between the drops, where the
combined effects of background flow, gravity, and interparticle
interactions drive the collision dynamics. A study of this problem may
explain the condensation-coalescence bottleneck (or the ‘size gap’ of 15
- 40 microns droplets) in warm rain formation, where neither
condensation nor gravitational collision alone is the dominant growth
mechanism. We have focused on studying the collision dynamics of
particle pairs subject to a background flow (simple shear flow,
turbulent flow) and gravity, incorporating hydrodynamic and
interparticle interactions.
In the first problem, we have studied the role of Brownian motion in the
coagulation of bidisperse like-charged spherical particles interacting
via non-continuum hydrodynamics, van der Waals, and electrostatic
interactions. We have found that electrostatic interactions can enhance
the collision rate between like-charged Brownian particles while
interacting through non-continuum hydrodynamics, and their charge ratio
is high. To consider the effect of a background flow, we have studied
the collision of hydrodynamically interacting particle pairs settling in
a laminar simple shear flow. By incorporating non-continuum
hydrodynamics, van der Waals interactions, and the coupled driving
forces of sedimentation and simple shear, our work provides collision
efficiency results relevant to flows of suspensions through vertical
pipes and channels, sampling of aerosols, and the transport of
particulate matter in riser reactors. Finally, we have also investigated
collision dynamics of sub-Kolmogorov interacting spheres rapidly
settling in a homogeneous isotropic turbulent flow. This work relied on
formulating an equation for the pair probability PDF and solving it
semi-analytically.
relevant to many environmental and industrial processes, such as droplet
growth in warm clouds and the aggregation of aerosol particles in
industrial settings. The evolution of the drop size distribution in
clouds depends on the collision rate between the drops, where the
combined effects of background flow, gravity, and interparticle
interactions drive the collision dynamics. A study of this problem may
explain the condensation-coalescence bottleneck (or the ‘size gap’ of 15
- 40 microns droplets) in warm rain formation, where neither
condensation nor gravitational collision alone is the dominant growth
mechanism. We have focused on studying the collision dynamics of
particle pairs subject to a background flow (simple shear flow,
turbulent flow) and gravity, incorporating hydrodynamic and
interparticle interactions.
In the first problem, we have studied the role of Brownian motion in the
coagulation of bidisperse like-charged spherical particles interacting
via non-continuum hydrodynamics, van der Waals, and electrostatic
interactions. We have found that electrostatic interactions can enhance
the collision rate between like-charged Brownian particles while
interacting through non-continuum hydrodynamics, and their charge ratio
is high. To consider the effect of a background flow, we have studied
the collision of hydrodynamically interacting particle pairs settling in
a laminar simple shear flow. By incorporating non-continuum
hydrodynamics, van der Waals interactions, and the coupled driving
forces of sedimentation and simple shear, our work provides collision
efficiency results relevant to flows of suspensions through vertical
pipes and channels, sampling of aerosols, and the transport of
particulate matter in riser reactors. Finally, we have also investigated
collision dynamics of sub-Kolmogorov interacting spheres rapidly
settling in a homogeneous isotropic turbulent flow. This work relied on
formulating an equation for the pair probability PDF and solving it
semi-analytically.