Fill in the blank to correctly complete the statement below the problem faced galloping gertie, the failed bridge across the Tacoma narrows, was caused because the engineers did not follow the perform tests on the prototype/testing/()step in the engineering design process

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa.s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)