What is Laminar and Turbulent Flow in Fluid Mechanics?

Fluid mechanics is a very important topic in mechanical engineering. As its name implies, fluid flow is the main topic of fluid mechanics. The flow of fluids is classified according to the different aspects. One of the classifications is the lamşnar and turbulent flows. 

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Difference between Laminar and Turbulent Flow

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The main difference between laminar and turbulent flows is the chaoticity of the flow. If the fluid flow is highly ordered and smooth, these fluid flows are called laminar flows. And the fluid flows are highly chaotic and mixing, this fluid flow is called turbulent flow. 

The fluid that has very high viscosities generally flows laminarly. You can see that oil which has a very high viscosity, flows very smoothly from an oil bottle. Also, fluids that have low viscosities tend to flow as turbulent. Air is one of the most important examples of turbulent flow.

If a flow shows both laminar and turbulent flow regimes, these fluid flows are classified as transitional flows. 

Reynolds Number

Reynolds number is a parameter that defined whether a flow is turbulent or laminar in the flows in circular ducts. 

According to this formula, ‘ρ’ is the density of the fluid that flows in the circular pipe which has the unit of kg/m^3. ‘Vaverage’ is the average velocity that fluid flows inside the pipe which has the unit of m/s. ‘D’ is the diameter of the circular pipe that fluid flow inside it which has the unit of m. ‘μ’ is the viscosity of the fluid that has a unit of N.m^2/s.  

According to the value of the Reynolds number, the fluid flow inside the circular pipe is classified as laminar or turbulent. 

  • If the Reynolds number that is calculated is smaller than 2300, the fluid flow is considered to be laminar. 
  • If the Reynolds number is between 2300 and 4000, the flow is considered a transitional flow. 
  • If the Reynolds number is above the 4000, the flow is considered a turbulent flow.

You can use the Reynolds Number calculator to see if the fluid flow that you are dealing with is laminar or turbulent. 

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The explanation of the laminar and turbulent flow in fluid mechanics can be summarized like this. 

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