The type of fluid flow is primarily dependent on the viscosity of the fluid and the velocity at which it is moving.
The flow remains laminar for more viscous and slow-moving fluids because the viscous forces dominate over inertial forces.
The flow starts to turn turbulent for viscous but high-velocity fluids because the inertial forces dominate the viscous forces.
So, to answer the question when inertial forces start dominating viscous forces the fluid molecules gain more and more energy and start moving in chaotic motions and the laminar flow turns into turbulent flow.
The type of fluid flow is primarily dependent on the viscosity of the fluid and the velocity at which it is moving.
The flow remains laminar for more viscous and slow-moving fluids because the viscous forces dominate over inertial forces.
The flow starts to turn turbulent for viscous but high-velocity fluids because the inertial forces dominate the viscous forces.
So, to answer the question when inertial forces start dominating viscous forces the fluid molecules gain more and more energy and start moving in chaotic motions and the laminar flow turns into turbulent flow.