Flow in a slightly inclined trough

If b is the bulge on the surface of an elastic liquid flowing down a channel inclined at an angle P to the horizontal, then 

This method can be used as a simple means of measuring Ni. 

If Ph is the extra pressure generated at the bottom of a hole set into a wall when an elastic hquid flows past it, then its value for various geometrical configurations is given by the following formulas  

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