I am trying to run a turbulent pipe flow simulation with turbulent Reynolds number of 600, for 15 seconds, the flow is pressure driven due to gravity enforced buoyancy force which gives kinematic viscosity input as 8.25E-0.5 N/m^2, if gravity value taken as 9.81.

But in this case the flow is unable to become turbulent for smagorinsky LES model. Is this because of the high viscosity input? because for same inputs and changing Re = 2400 and \nu = 2.06E-05 the flow starts to become turbulent within the span of 15 seconds.

1. to make my simulation run changing gravity value and keeping the nu = 2.06e-05 to obtain same Re = 600 will be a solution's to this?? (I'm trying to check this with trial runs)

2. Why does this happen? any physical intuitions for this kinda behavior with \nu values ??