Question

3a. If a typical cherry pit is spherical, with 4 mm diameter, what is the fastest speed it can be spat out before it is expected to set up turbulent air flows around it, thereby making its trajectory less efficient? The viscosity of air with density 1.1 kg/m3 is 0.00002 N-s/m2 .

3b. If a much smaller pit is found, one with half the diameter of the first, how much faster can IT now be spat before turbulent flow is expected? (Note: in this question the turbulent flow is only for initial conditions, as the air’s viscosity will quickly slow down the pit mid-air, thus reducing the Reynold’s number to below streamline levels. So turbulent flow may only be expected during the early stages of the trajectory)

Answer 1

I assume flow is laminar when N<2000, after that we can expect turbulence in flow,