The hydrodynamic and surface tension forces exerted during combing

1 The hydrodynamic and surface tension forces exerted during combing 

We begin by estimating the force exerted by the meniscus on the nanotube, Fm, given by.  

We can use several models to estimate the hydrodynamic frictional force. A simple way is to start with the fluid force on the cylinder immersed in perpendicular laminar flow this would be an 

Thus the surface tension force is on the order of 0.1 nN, while the hydrodynamic force is at most on the order of 1 pN. This implies that the alignment is probably due to surface tension forces, which explains why alignment is perpendicular to the meniscus rather than parallel to fluid flow. 

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