Transport in Systems with Vanishing Gradients

Illustration 1.1 Transport in Systems with Vanishing Gradients 

It frequently happens in transport processes that the driving gradient vanishes at some position in the system, without inhibiting the flow of mass, heat, or momentum. There are two special situations that give rise to such behavior  

Systems with vanishing gradients (a) catalyst peUet (b) viscous flow in a pipe (c) diffusion into capillary (d) polymer extruder. 

---