# Which law is followed by the velocity distribution in turbulent boundary layer?

## Which law is followed by the velocity distribution in turbulent boundary layer?

logarithmic law

On observing the above equation we can say that velocity distribution in the turbulent boundary layer follows logarithmic law . Note: The above equation is valid for both smooth and rough pipes.

## How does velocity affect boundary layer?

The fuller velocity profile of the turbulent boundary layer allows it to sustain the adverse pressure gradient without separating. Thus, although the skin friction is increased, overall drag is decreased.

**Does boundary layer thickness increase with velocity?**

This occurs due to friction between the fluid layer in contact and the plate. As the plate is fixed, it tries to drag the fluid down. The definition of boundary layer is the thickness at which the velocity of the fluid is 99% of that of free stream fluid. Hence boundary layer thickness increases.

**Which of the following is responsible for the separation of boundary layer?**

Separation takes place due to excessive momentum loss near the wall in a boundary layer trying to move downstream against increasing pressure, i.e., , which is called adverse pressure gradient.

### What causes flow separation?

Separation occurs due to an adverse pressure gradient encountered as the flow expands, causing an extended region of separated flow. The part of the flow that separates the recirculating flow and the flow through the central region of the duct is called the dividing streamline.

### How do you reduce boundary layers?

Rotation of the cylinder can reduce or eliminate the boundary layer that is formed on the side which is moving in the same direction as the freestream. The side moving against the flow also exhibits only partial separation of the boundary layer.

**Is velocity constant in laminar flow?**

In laminar flow, sometimes called streamline flow, the velocity, pressure, and other flow properties at each point in the fluid remain constant.

**What are the processes in the turbulent boundary layer?**

The first one is the presence of low-speed streaks that develop in and from the viscous sublayer, the region very close to the bed where viscous forces dominate due to the very low velocity of the flow. The second process is the ejection of fluid from these low-speed streaks into the fast-flowing flow higher up in the turbulent boundary layer.

#### How are particles transported in a turbulent flow?

Since the fluid body has no acceleration the resultant force in the direction of motion should be equal to zero. where P = Wetted perimeter. According to this theory, in turbulent condition the particles of the fluid get transported from one layer of some velocity to another layer of a different velocity.

#### Where does the ejection incursion model apply in a turbulent boundary layer?

The ejection–incursion model applies mostly to the region near the bed and is generally associated with coherent turbulent flow structures whose sizes are small in relation to the height of the turbulent boundary layer or the depth of flow.

**Which is true of the Universal velocity distribution equation?**

Prandtl further assumed that the shearing stress remains practically constant. Prandtl’s universal velocity distribution equation is valid in the central region of the pipe where the turbulent flow is fully developed. But in the regions close to the pipe wall the flow is not fully turbulent, and is more close to laminar flow.