# Technical Interview Questions - 8

Technical Interview Questions - 8 Contains following Questions

81. Pressure drop equation for horizontal pipe line in laminar flow condition?
82. What is application of atomizer in Spray dryer?
83. What are the units of Dynamic Viscosity?
84. What is Elutriation ?
85. What is ji

### 81. Pressure drop equation for horizontal pipe line in laminar flow condition?

In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe.

The assumptions of the equation are that the flow is laminar viscous and incompressible and the flow is through a constant circular cross-section that is substantially longer than its diameter.

The equation is als known as the Hagen–Poiseuille law, Poiseuille law and Poiseuille equation.

The governing equation is,

### 82. What is application of atomizer in Spray dryer?

Atomizer converts liquid in tiny droplets.

### 83. What are the units of Dynamic Viscosity?

Dynamic viscosity has the units of cP (Centi Poise), Poise(P) or in M.K.S units it has the units Kg/m.s.

### 84. What is Elutriation ?

Elutriation: It is a separation method, which depends on the settling velocity of the particles in the fluid.

In this process of separation, the material is placed in a rising fluid having a fixed upward velocity,
particles whose normal falling velocity is less than the velocity of the fluid will be carried upward and out of the vessel.

If fractions obtained from a series of fluid velocities are collected and weighed, a complete size analysis may be obtained.