scholarly journals Tank-treading as a means of propulsion in viscous shear flows

2011 ◽  
Vol 680 ◽  
pp. 265-286 ◽  
Author(s):  
PIERO OLLA
Keyword(s):  
Shear Flows ◽  
Analytical Calculation ◽  
Concentration Field ◽  
Shape Evolution ◽  
Bending Rigidity ◽  
Vesicle Shapes ◽  
Viscous Shear ◽  
Hydrodynamic Stresses ◽  
Spherical Limit ◽  
Stationary Shape

The use of tank-treading as a means of propulsion for microswimmers in viscous shear flows is taken into account. We discuss the possibility of a vesicle to control the drift in an external shear flow, by locally varying the bending rigidity of its membrane. By analytical calculation in the quasi-spherical limit, the stationary shape and the orientation of the tank-treading vesicle in the external flow are determined, working to lowest order in the membrane inhomogeneity. The membrane inhomogeneity acts in the shape evolution equation as an additional force term, which can be used to balance the effect of the hydrodynamic stresses, thus allowing the vesicle to assume shapes and orientations that are impossible otherwise. The vesicle shapes and orientations required for migration transverse to the flow, together with the bending rigidity profiles leading to such shapes and orientations, are determined. Considering the variations in the concentration experienced during tank-treading, a simple model is presented, in which a vesicle is able to migrate up or down the gradient of a concentration field by stiffening or softening of its membrane.

ICCM2015(Paper ID:1148): DPD Simulation of the Movement and Deformation of Bioconcave Cells

2016 ◽  
Vol 13 (04) ◽  
pp. 1641003
Author(s):  
L. W. Zhou ◽  
Yu-Qian Zhang ◽  
Xiao-Long Deng ◽  
M. B. Liu
Keyword(s):  
Red Blood Cells ◽  
Poiseuille Flow ◽  
Blood Cells ◽  
Shear Flows ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
Experimental Results ◽  
Shape Evolution ◽  
Movement And Deformation ◽  
Dpd Simulation

This paper presents a dissipative particle dynamics (DPDs) method for investigating the movement and deformation of biconcave shape red blood cells (RBCs) with the worm-like chain (WLC) bead spring. First, the stretching of a RBC is modeled and the obtained shape evolution of the cell agrees well with experimental results. Second, the movement and deformation of a RBC in shear flows are investigated and three typical modes (tumbling, intermittent and tank-treading) are observed. Lastly, an illustrating example of multi-RBCs in Poiseuille flow in a tube is simulated. We conclude that the presented DPD method with WLC spring can effectively model the movement and deformation of bioconcave cells.

scholarly journals Numerical analysis of viscous shear flows around a circular cylinder.

1987 ◽  
Vol 53 (493) ◽  
pp. 2756-2761 ◽  
Author(s):  
Kohzaburo NAKABAYASHI ◽  
Naoyuki YOSHIDA ◽  
Tyusei AOI
Keyword(s):  
Numerical Analysis ◽  
Circular Cylinder ◽  
Shear Flows ◽  
Viscous Shear

Dissolved Oxygen Concentration Field Measurement in Microfluidics Using PtOEP/PS Film Sensor

2011 ◽  
Author(s):  
Seung Jae Yi ◽  
Dae Hun Song ◽  
Kyung Chun Kim
Keyword(s):  
Dissolved Oxygen ◽  
Uv Light ◽  
Concentration Field ◽  
Film Sensor ◽  
Light Emitting ◽  
Water Flows ◽  
Viscous Shear ◽  
Planar Optode ◽  
Do Concentration ◽  
Uv Leds

A planar optode system based on an oxygen quenchable luminophore platinum (II) octaethyporphrin (PtOEP) bound with thin polystyrene (PS) film and UV light-emitting diodes (UV-LEDs) was developed to measure the dissolved oxygen (DO) concentration field in microscale water flows. An intensity-based method adopting a pixel-to-pixel in situ calibration technique was used to visualize DO concentration fields in a Y-shaped microchannel. The achievable spatial resolution of the acquired concentration map could be as high as 2.94 μm. The diffusion process of DO through the interface between two parallel water flows having different DO concentrations was quantitatively analyzed. We found that the thickness of the concentration gradient of DO increased as the Reynolds number decreased. The ratio of diffusion length scales coincided with the ratio of inner scales of viscous shear layers in the microchannel for two different Reynolds numbers.

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