Multiphase Flow Calculator

Model gas–liquid flow fast for design work. Switch correlations, check Reynolds, and compute friction instantly. Download results as CSV or a clean PDF file.

Meta: Estimate two-phase pressure drop and flow regime. Compare predicted liquid holdup using selectable models. Enter pipe and fluid data, then export reports quickly.

Input data

Volumetric liquid rate at line conditions.
Volumetric gas rate at line conditions.
Use the actual ID after lining or scaling.
Total along the centerline of the pipe.
Default is commercial steel (~4.5e−5 m).
Positive for uphill flow, negative for downhill.
Typical: water 1000, light oil 700-900.
1 mPa·s = 0.001 Pa·s.
Depends on pressure, temperature, and composition.
Air is ~1.8e-5 Pa·s near ambient.
Holdup affects mixture properties and ΔP.
Laminar uses 64/Re automatically.
Reset

Formula used

  • A = πD²/4 (pipe area)
  • v_sl = Q_l/A, v_sg = Q_g/A
  • v_m = v_sl + v_sg
  • α = Q_g / (Q_g + Q_l) (homogeneous)
  • ρ_m = αρ_g + (1−α)ρ_l
  • μ_m = αμ_g + (1−α)μ_l (simple blend)
  • Re = ρ_m v_m D / μ_m
  • ΔP_f = f (L/D) (ρ_m v_m² / 2)
  • ΔP_e = ρ_m g L sin(θ)
  • ΔP = ΔP_f + ΔP_e

Notes: This tool uses a homogeneous mixture approach for quick estimates. Real pipelines may require mechanistic correlations and phase behavior for accuracy.

How to use this calculator

  1. Enter liquid and gas volumetric flow rates at line conditions.
  2. Provide pipe ID, length, roughness, and inclination angle.
  3. Input fluid densities and viscosities for both phases.
  4. Select a holdup model and a friction correlation if needed.
  5. Press Submit to display pressure change and supporting outputs.
  6. Use Download buttons to export CSV or PDF reports.

Example data table

Scenario Q_l Q_g D L ρ_l μ_l ρ_g μ_g θ ΔP (Pa) Regime
Light oil + dense gas 12 m³/h 18 m³/h 0.10 m 250 m 950 kg/m³ 0.0035 Pa·s 12 kg/m³ 0.000012 Pa·s 0° 1.353e+4 Transitional
Water + low gas rate 10 m³/h 2 m³/h 0.08 m 150 m 1000 kg/m³ 0.0010 Pa·s 2 kg/m³ 0.000018 Pa·s +5° Run the form to compute Typically bubbly/slug
High gas in horizontal line 3 m³/h 60 m³/h 0.12 m 300 m 850 kg/m³ 0.0025 Pa·s 8 kg/m³ 0.000013 Pa·s 0° Run the form to compute Often annular

Example rows are illustrative and should not replace detailed multiphase design.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.