Day 42-Nov 1-Worksheet-Diploma-Boundary layer theory

In the boundary layer, velocity becomes 99 % of free-stream velocity at a distance known as —

(a)  

The velocity profile in a laminar boundary layer is —

(a)  

In turbulent boundary layer, the velocity distribution is approximately —

• Linear

• Logarithmic

• Uniform

• Parabolic

At what Reynolds number does laminar flow generally become turbulent on a flat plate?

• Re = 2 × 10⁴

• Re = 5 × 10⁵

• Re = 10⁶

• Re = 10⁷

Which of the following layers exists within the turbulent boundary layer due to high viscous effects?

• Transition layer

• Outer layer

• Laminar sub-layer

• Wake region

In a laminar flow over a flat plate, boundary-layer thickness (δ) varies with distance x as —

• δ ∝ x¹/⁵

• δ ∝ x¹/²

• δ ∝ x

• δ ∝ x²

Boundary-layer separation occurs when —

• ∂u/∂y > 0

• ∂u/∂y = 0

• ∂u/∂y < 0

The region near the solid boundary where viscous effects dominate is called (a)   .

The displacement thickness represents the distance by which the (a)   is displaced away from the wall due to boundary layer.

The ratio of displacement thickness to momentum thickness is called (a)   .