The study focuses on the rheological behavior of a fluid based viscoelastic surfactant (Surfogel grade D, type 70-100, produced by JSC "Polyex") in wide range strain rates. This is used for hydraulic fracturing technology as proppant-carrying and proppant-retaining order to enhance oil recovery, including those with hard-to-recover gas reserves. Quasi-static experiments determine values dynamic...

the effect of weak shear thickening and shear thinning on the stability of the taylor-couette flow is explored for a carreau-bird fluid in the narrow-gap limit. the galerkin projection method is used to derive a low-order dynamical system from the conservation of mass and momentum equations. in comparison with the newtonian system, the present equations include additional nonlinear coupling in ...

A polygonal mesh is a connected subset of a polyhedral surface. We address the problem whether the intrinsic metric of a mesh, i.e., its development, can determine the exterior metric. If this is the case then the mesh is rigid. Among the non-rigid cases even flexible versions are possible. We concentrate on quadrangular meshes and in particular on a mesh with a flat pose in which the quadrangl...

The velocity field and the shear stress corresponding to motion of an Oldroyd-B fluid between two infinite coaxial circular cylinders are established by means of the Hankel transforms. The flow of the fluid is produced due to the time dependent axial shear stress applied on the boundary of the inner cylinder. The exact solutions, presented under a series form, can easily be specialized to give ...

The Navier-Stokes equations are solved exactly, assuming the Navier slip boundary condition, for flow between coaxial circular cylinders (with possibly different slip lengths at the inner and outer walls), and flow in an equilateral triangular pipe. The velocity fields and total flow rates are found analytically. A relatively small slip length can lead to a large increase in the total rate of f...

Carbon nanotubes are a new allotrope of carbon which emerged from the fullerene family [1]. Carbon nanotubes have been discovered by high resolution transmission electron microscopy (HRTEM) in 1991 by Iijima [2]. A single wall carbon nanotube is constituted of one atomic plane with a graphite-like arrangement of C atoms – called a graphene sheet – which is perfectly rolled into a cylinder (Fig....