Falls drag-related

It may be assumed that the drag force F of the fluid on the particles under the free falling conditions is given by Stokes law and that the relation between the fluidisation velocity uc and voidage, e, for particles of terminal velocity, u0, is given by ... 

Each submolecule will experience a frictional drag with the solvent represented by the frictional coefficient /0. This drag is related to the frictional coefficient of the monomer unit (0- If there are x monomer units per link then the frictional coefficient of a link is x(0- If we aPply a step strain to the polymer chain it will deform and its entropy will fall. In order to attain its equilibrium conformation and maximum entropy the chain will rearrange itself by diffusion. The instantaneous elastic response can be thought of as being due to an entropic spring . The drag on each submolecule can be treated in terms of the motion of the N+ 1 ends of the submolecules. We can think of these as beads linked... 

As an alternative, the data used for the generation of equation 3.13 for the relation between drag coefficient and particle Reynolds number may be expressed as an explicit relation between Re 0 (the value of Re at the terminal falling condition of the particle) and the Galileo number Ga. The equation takes the form l0 ... 

At a low Re3uiolds number, the drag diameter equals the surface diameter of convex particles. For this case, the Stokes diameter, defined as the free-fall diameter in the laminar flow region, is related to sphericity as follows ... 

The drag reduction results are considered from three standpoints characteristics of polymer slurry drag reduction, extension of the drag reduction lifetime by polymer slurry (time taken for flow to fall back to it s pre-drag-reduced level), and increase in useful effect related to the use of polymer slurry as a drag-reducing agent. 

---