Choose ΔP or P1/P2; enter D1 > D2 > 0, density > 0 and Cd > 0. ΔP may be zero. Viscosity is optional and positive. Optional 1–20 rows: ΔP, Cd, using the selected pressure unit.

Pressure input mode

Pressure unit

Pressure difference ΔP

Upstream pressure P1

Throat pressure P2

Upstream diameter D1

Throat diameter D2

Length unit

Density ρ (kg/m³)

User discharge coefficient Cd

Dynamic viscosity μ (Pa·s), optional

Optional scenarios: ΔP, Cd — one pair per line (1–20)

Enter your values and select each required model and unit.

Calculated snapshot

Steady incompressible Bernoulli and continuity, with user Cd applied to flow. Gas/compressibility needs a normative expansibility model and operating context; it remains unavailable. No default Cd or fluid properties.

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A QUICK WALKTHROUGH

How to use this tool

Choose ΔP or P1/P2; enter D1 > D2 > 0, density > 0 and Cd > 0. ΔP may be zero. Viscosity is optional and positive. Optional 1–20 rows: ΔP, Cd, using the selected pressure unit.
β = D2/D1; A = πD²/4; Qideal = A2 √[2ΔP/(ρ(1−β⁴))]; Q = Cd Qideal; v1 = Q/A1; v2 = Q/A2; Re1 = ρv1D1/μ; Re2 = ρv2D2/μ.
Calculations and report stay in this browser. Copy or download only the last successful unchanged snapshot.

Scope and limitations

Equations

β = D2/D1; A = πD²/4; Qideal = A2 √[2ΔP/(ρ(1−β⁴))]; Q = Cd Qideal; v1 = Q/A1; v2 = Q/A2; Re1 = ρv1D1/μ; Re2 = ρv2D2/μ.

How to use

Choose ΔP or P1/P2; enter D1 > D2 > 0, density > 0 and Cd > 0. ΔP may be zero. Viscosity is optional and positive. Optional 1–20 rows: ΔP, Cd, using the selected pressure unit.

GOOD TO KNOW

Common questions

What does this result establish?

Are inputs uploaded?