Question

Fluid Mechanics Topic
Why is it important to know if the flow is laminar or turbulent ?
Like why do we care to know whether its laminar or turbulent.
Please i need a correct logical answer. It has nothing to do with reynolds number.

Answer 1

When the flow is laminar, the fluid flow is characterized by the streamline flow while in turbulent conditions, eddies are formed causing mixing of the fluid during the flow.

We care to know whether the flow is turbulent or laminar because of the following reasons:

1] More heat is transferred when the flow is turbulent due to convection currents.

Eg: When the water is continuously stirred, it boils faster because each and every drop of water gets heated due to the turbulent action.

Similarly,

In the pipelines or heat exchanger, turbulence plays an important role.

When the required amount of heat is given to a process stream or a utility at a certain flow rate in a heat exchanger, turbulence helps to attain the heat transfer faster, thereby reducing the size of the heat exchanger and hence the process is more profitable compared to the laminar flow.

2] Heat transfer is just one case among the 3 in the transport phenomena.

Others are mass transfer and fluid flow.

From the example given above, it's therefore very important to know whether the flow is laminar or turbulent from the design point of view.