Velocity Profile in the Active Layer

Application of integral methods for solving boundary layer flows involves fitting the velocity profile to a polynomial form 

Following the fluid flow analogy, the most obvious choice for a free surface boundary condition is to allow the shear stresses to vanish and thereby force the shear rate to go to zero (i.e., du/dy = 0). Although this condition has been used in chute flow calculations (Savage, 1979 Campbell and Brenen, 1985 etc.) it forces the velocity profile to a 

2 Conditions at the interface Between Plug Flow and Active Layer 

Inclusion of these constraints into the parabolic velocity profile provides an analytical expression for the profile (Appendix 4B)  

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Figure 4.2 Measured exposed surface velocity profile in the active layer (15 percent fill and 5rpm).

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