FLUID MECHANICS

LAMINAR FLOW AND TURBULENT FLOWB.H. Gardi collage of engineering and technology

JAYDEEP KOSHIYA 13CE034 7TH SEM. CIVIL

LAMINAR FLOW• DEFINITION:-• A laminar flow is one in which the fluid particles move in layers or lamina with one layer sliding over the other.• Fluid element move in well defined paths and they retain

the same relative position at successive cross-section of the flow passage.• This flow is also known as the streamline.

• This type of flow Occurs when the fluid flows in parallel layers, with no disruption between the layers, when the velocity of flow is low and liquids having a high viscosity

• For this flow streamline ,sreakline and pathline is identically .

HISTORY OF LAMINAR FLOW

• The phenomenon was first investigated in the 1880s by osbourne reynolds in an experiment which has become a classic in fluid mechanics.• In laminar flow the motion of the particles of fluid is very orderly with all particles moving in straight lines parallel to the pipe walls.

Laminar Flow

TurbulentFlow

After many experiments he saw that this expression =density, = viscosity = d=diameter • Laminar flow: < 2000 • Transitional flow: 2000 < < 4000 • Turbulent flow: > 4000

Property of laminar flow

• Re < 2000 • 'low' velocity • Dye does not mix with water • Fluid particles move in straight lines • Simple mathematical analysis possible.

Ex. Blood flow through capillaries is laminar flow, as it satisfies the 6 conditions

APPLICATION OF LAMINAR FLOW

• Most popular use of laminar flow is in fountain.Like , in burj –al- Arab. In Dubai.• Laminar flow is not only in liquidBut it is also in gases.

TURBULENT FLOW

• DEFINITION:-

It is this type of flow in which the fluid particles move in a zig-zag way• All fluid particles are disturbed and they mix with each other.• Thus this is continuos transfer of momentum to adjacent layer.

•Due to movement of this particles in zig zag way,the eddies formation take place which are responsible for high energy losses.

Property of turbulent flow• Re > 4000 •'high' velocity •Dye mixes rapidly and completely •Particle paths completely irregular •Average motion is in the direction of the flow.•Changes/fluctuations are very difficult to detect. Must use laser. •Mathematical analysis very difficult - so experimental measures are used •Most common type of flow