Two-Phase Flow Pressure Drop

Gas + liquid ΔP by Lockhart–Martinelli / Chisholm — backend-computed

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Engineering Tips

Two-phase (gas + liquid) pressure drop by the Lockhart–Martinelli separated-flow model with Chisholm’s two-phase multiplier. The numeric solution runs on the calculation backend.

Lockhart–Martinelli:

• X² = (dP/dx)_L / (dP/dx)_G

• φ_L² = 1 + C/X + 1/X²

• (dP/dx)_TP = φ_L²·(dP/dx)_L

Recommended values

Properties: Evaluate densities and viscosities at the segment’s average pressure and temperature.
Gas density: ρ_G = P·M/(Z·R·T) — recompute per segment as pressure falls.
Inclination: + uphill adds static head; − downhill recovers it.

Limitations

Screening: Single-segment, constant-property estimate; march long lines segment-by-segment as density changes.
Holdup: Reports no-slip holdup λ_L; slip holdup and a rigorous regime map need Beggs–Brill (planned). Regime badge is indicative.

About the standards

Lockhart–Martinelli (1949): separated-flow two-phase pressure drop.
Chisholm (1967): two-phase multiplier constant C.

Two-Phase Flow Pressure Drop

Input Parameters

Liquid Phase

Gas Phase

Pipe Geometry