Flow in pipe and Reynolds Number

Flow in pipe and Reynolds NumberPrepared byMallika BoonmeeDepartment of Biotechnology KKU

Flow in pipe

The VDO clip shows the complete range of flow in circular pipe.Laminar flowTransition flowTurbulent flowPlay the VDO & try to indicate the start of each flow region.Next

What do you think this type of flow is?Choose your answerLaminar flowTransition flow

Yes, this is a laminar flowYou can see that the flow is continuous, going in the same direction (from left to right).The curve you see is caused by unequal forces from the pipe wall. NextSee more about laminar flow

No, this is not a transition flow

You can see that the flow is continuous, going in the same direction (from left to right).The curve you see is caused by unequal forces from the pipe wall. This is a laminar flowNextSee more about laminar flow

More on laminar flow

This VDO clip about viscosity will help you understand how particles move in laminar flowParticles in different flow layers and positions (different colours) do not cross or overtake each other during the flow.If the flow is reversed, particles would take the same path back to the beginning point.Next

What about this flow?It is still a laminar flowIt is definitely a transition flow

No.This flow is a transition flow.

The flow path in yellow circle showed diffusion of particles in radial direction while the flow is along the tube length (direction from left to right).FlowNext

Yes, the flow is a transition flow.

The flow path in yellow circle showed diffusion of particles in radial direction while the flow is along the tube length (direction from left to right).FlowNext

Is this flow transition or turbulent?It is a transition flow.Its already turbulent flow.

Yes.This flow is still in transition region.This flow is still transition because there are both laminar regions (yellow arrows) and turbulent regions (red arrows) in the flow.Next

No.This flow is still in transition region.This flow is still transition because there are both laminar regions (yellow arrows) and turbulent regions (red arrows) in the flow.Next

This is how turbulent flow looks like.You can see that there is no laminar region in the flow.Every points in the flow are turbulent.Next to Reynolds number

Reynolds numberis a dimensionless number with the formulaYou should know the meaning of each symbols and their units