What are the three types of segregated flow?

• A. Laminar, Transitional, and Turbulent
• B. Plug flow, Slug, and Annular
• C. Segregated, Intermittent, and Distributive
• D. Stratified, Wavy, and Annular

Answer: (D)

In segregated flow, the two phases occupy distinct regions in the pipe cross-section rather than being mixed together. The three common segregated patterns are stratified, stratified wavy, and annular.

Stratified means the liquid settles along the bottom of a horizontal pipe while the gas flows above it, with a relatively flat interface between them. Stratified wavy adds surface instability to that arrangement, so the interface develops waves but the phases remain largely separated. Annular flow occurs when a liquid film coats the pipe walls and the gas flows mainly through the center, forming a core gas region with a continuous liquid film on the walls.

These patterns matter because they determine how much of each phase is present in a given cross-section (holdup) and how the mixture behaves in terms of pressure drop and heat/mass transfer.