Microphysics of mass-transport in coupled droplet-pairs at low Reynolds number and the role of convective dynamics

2016 ◽  
Vol 28 (6) ◽  
pp. 063602 ◽  
Author(s):  
Qingming Dong ◽  
Amalendu Sau
Keyword(s):  
Reynolds Number ◽  
Mass Transport ◽  
Low Reynolds Number ◽  
Low Reynolds

Unsteady swimming of small organisms

2012 ◽  
Vol 702 ◽  
pp. 286-297 ◽  
Author(s):  
S. Wang ◽  
A. M. Ardekani
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Fundamental Equation ◽  
Added Mass ◽  
Natural Environments ◽  
Mean Velocity ◽  
Unsteady Forces ◽  
Uniform Background ◽  
Low Reynolds

AbstractSmall planktonic organisms ubiquitously display unsteady or impulsive motion to attack a prey or escape a predator in natural environments. Despite this, the role of unsteady forces such as history and added mass forces on the low-Reynolds-number propulsion of small organisms, e.g. Paramecium, is poorly understood. In this paper, we derive the fundamental equation of motion for an organism swimming by means of the surface distortion in a non-uniform background flow field at a low-Reynolds-number regime. We show that the history and added mass forces are important as the product of Reynolds number and Strouhal number increases above unity. Our results for an unsteady squirmer show that unsteady inertial effects can lead to a non-zero mean velocity for the cases with zero streaming parameters, which have zero mean velocity in the absence of inertia.

Vertical Migration of the Small Organisms in a Stratified Fluid

2012 ◽  
Author(s):  
Amin Doostmohammadi ◽  
Arezoo M. Ardekani
Keyword(s):  
Reynolds Number ◽  
Vertical Migration ◽  
Low Reynolds Number ◽  
Nonlinear Effects ◽  
Stratified Fluid ◽  
Salinity Gradients ◽  
Density Interfaces ◽  
Low Reynolds ◽  
Made In

Significant progress has been made in analyzing low-Reynolds number locomotion in homogeneous fluids. Even though density interfaces due to temperature or salinity gradients (pycnoclines), ubiquitously occur in oceans and lakes, the effects of stratification on the hydrodynamics of swimming of small organisms, their interaction with each other and their migration are very poorly understood. In this article, we implement a direct numerical simulation of the migration of swimmers at pycnoclines and illustrate the role of the diffusivity of the stratified agent on the swimming of small organisms. We demonstrate that for an archetypal swimmer model, squirmer, the migration at density stratified fluid can be largely influenced by buoyancy effects. We also show that the effects of density stratification are increased as the diffusivitty of the stratified agent is reduced. The results demonstrate that the stratification suppresses the vertical migration and consequently affects the life of low Reynolds number swimmers across pycnoclines. Our recent computational results reveal the full nonlinear effects of stratification on the locomotion of small organisms.

scholarly journals Role of symmetry in driven propulsion at low Reynolds number

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
Johannes Sachs ◽  
Konstantin I. Morozov ◽  
Oded Kenneth ◽  
Tian Qiu ◽  
Nico Segreto ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Low Reynolds

Experimental Investigation on Blunt-Edged UTM Delta Wing VFE-2 Configurations at Low Reynolds Number

2018 ◽  
Vol 12 (3) ◽  
pp. 255
Author(s):  
Muhammad Zal Aminullah Daman Huri ◽  
Shabudin Bin Mat ◽  
Mazuriah Said ◽  
Shuhaimi Mansor ◽  
Md. Nizam Dahalan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Delta Wing ◽  
Low Reynolds Number ◽  
Low Reynolds
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