Shear flow themselves. In a shearing flow, adjacent layers of fluid move parallel to each other with different speeds. Viscous fluids resist this shearing motion. For a Newtonian fluid, the stress exerted by the fluid in resistance to the shear is proportional to the strain rate or shear rate. A simple example of a shear flow is Couette flow, in which a fluid is trapped between two large parallel plates, and one plate is moved with some relative velocity to the other. Here, the strain rate is simply the relative velocity divided by the distance between the plates. Shear flows in fluids
Mass flow action within their cells . Solute flow is driven by a difference in hydraulic pressure created from the unloading of solutes in the sink tissues. That is, as solutes are off-loaded into sink cells (by active or passive transport), the density of the phloem liquid decreases locally, creating a pressure gradient. Mass flow "This article is about the flow of fluids in biological systems. For use of "mass flow" in physics see Fluid Dynamics. For "bulk flow" in physics see Advection. For "protein transport" in cell biology see Bulk movement." Mass flow, also known as “mass transfer” and “bulk flow”,