Two-Phase Flow Regime Map (Mandhane Map)
Input your pipe geometry and flow rates to instantly identify your flow regime on the Mandhane (1974) flow regime map — with practical engineering recommendations.
Pipe & Flow Parameters
Pipe Area
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Superficial Liquid Vel. (Vsl)
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Superficial Gas Vel. (Vsg)
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Flow Regime Identification
Vsl
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ft/s
Vsg
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ft/s
Mixture Velocity
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ft/s
Input Gas Fraction (GVF)
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fraction
Engineering Recommendation
Enter your inputs to see recommendations.
Mandhane Flow Regime Map
Mandhane, Gregory & Aziz (1974) — horizontal pipe, air-water at atmospheric conditions
The large pulsing dot marks your operating point. Regime boundaries are approximate — exact transitions depend on fluid properties, pipe inclination, and pressure. For engineering decisions, use Beggs-Brill or Mechanistic models.
How boundaries are computed & assumptions
Reference: Mandhane, J.M., Gregory, G.A., Aziz, K. (1974). A flow pattern map for gas-liquid flow in horizontal pipes. International Journal of Multiphase Flow, 1(4), 537-553.
Axes: Superficial gas velocity Vsg (x-axis) and superficial liquid velocity Vsl (y-axis), both in ft/s on log-log scale.
Dispersed Bubble: Vsl > 5 ft/s AND Vsg < 5 ft/s (high liquid, low gas)
Bubble: Vsg < 1 ft/s AND Vsl > 0.5 ft/s (low gas, moderate liquid)
Slug: 0.3 ≤ Vsg ≤ 10 ft/s AND 0.1 ≤ Vsl ≤ 10 ft/s (dominant middle region)
Stratified Smooth: Vsg < 3 ft/s AND Vsl < 0.1 ft/s (low velocities, gravity-dominated)
Stratified Wavy: 3 ≤ Vsg ≤ 20 ft/s AND Vsl < 0.3 ft/s (moderate-high gas, low liquid)
Annular: Vsg > 10 ft/s (high gas velocity — gas core, liquid film at wall)
Conversions: bbl/d × 5.615/86400 = ft³/s | MMscf/d × 10&sup6;/86400 = ft³/s | A = π/4 × (ID/12)² ft²
Limitations: The Mandhane map was developed for near-horizontal pipes with air-water at atmospheric pressure. For inclined pipes, high-pressure systems, or non-Newtonian liquids, use mechanistic models (Taitel-Dukler, Barnea) or full multiphase simulators.
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Book a free strategy call →Understanding the Mandhane Flow Regime Map
Two-phase gas-liquid flow in horizontal pipes exhibits distinct flow patterns — or flow regimes — depending on the relative velocities and volumetric fractions of each phase. The Mandhane flow regime map (Mandhane, Gregory & Aziz, 1974) remains the most widely used empirical tool for identifying which regime governs your system. It plots superficial gas velocity (Vsg) on the x-axis against superficial liquid velocity (Vsl) on the y-axis, both on log-log scales, and delineates regions corresponding to each flow pattern.
The superficial velocity of each phase is the velocity that phase would have if it alone occupied the full pipe cross-section: Vs = Q / A, where Q is the volumetric flow rate and A is the pipe cross-sectional area. These are not actual phase velocities, but convenient dimensionless-like parameters that collapse flow regime transitions onto a single map regardless of pipe diameter (within a range).
Flow Regimes and Their Engineering Implications
Bubble flow occurs at low gas velocities and moderate-to-high liquid velocities. Gas is dispersed as small bubbles carried by the continuous liquid phase. This is generally the most stable and predictable regime, with smooth pressure gradients and good metering accuracy.
Slug flow is the most operationally problematic regime, occupying the large central region of the Mandhane map. It is characterized by alternating liquid slugs and elongated gas bubbles (Taylor bubbles). Slug flow causes severe pressure pulsations, mechanical vibrations, liquid surges at separators, and can damage instrumentation. Slug catchers, choke management, and flow conditioning are common mitigation strategies.
Stratified smooth and stratified wavy flow occur at low liquid rates where gravity separates the phases into a liquid layer at the bottom and a gas layer at the top. The bottom of pipe (6 o’clock position) is particularly vulnerable to CO2 and H2S corrosion in stratified flow because the liquid-gas interface keeps the pipe wall wet with condensed water. Regular pigging, corrosion inhibitor injection, or increasing liquid velocity are standard countermeasures.
Annular flow occurs at high gas velocities. Gas occupies the pipe core while liquid forms a thin annular film on the pipe wall. Annular flow can cause erosion, particularly at bends and tees, and the mixture velocity should be checked against the API RP 14E erosional velocity limit (Ve = C / √ρm).
Dispersed bubble flow occurs at very high liquid rates with low gas content. Turbulence disperses gas as fine bubbles throughout the liquid. This is generally a stable regime but can create challenges for gas-liquid separation and foam formation.
Limitations and When to Use Mechanistic Models
The Mandhane map was developed for near-horizontal, air-water systems at atmospheric pressure. It should be used for screening and preliminary assessment only. For engineering design, especially in inclined or vertical pipes, high-pressure systems, or with non-water fluids, mechanistic models such as Taitel-Dukler (1976), Barnea (1987), or full multiphase simulators (OLGA, LedaFlow) should be used. The Beggs-Brill correlation is widely used in practice for inclined multiphase pipelines.