Calculator · Fluid Mechanics
Flow Rate & Velocity Calculator
One cross-section, one mean speed, one flow rate. The area may come from a pipe diameter, a rectangular duct or a number you already have.
Inputs
Used only for the mass flow rate; the volumetric relation does not need it.
Results
Volumetric flow rate Q = A V
0.015708 m³/s
| Flow area A | 0.007854 m² |
|---|---|
| Mean speed V | 2 m/s |
| Volumetric flow rate Q | 0.015708 m³/s |
| Mass flow rate ṁ = ρQ | 15.708 kg/s |
Assumptions
- · Steady, incompressible flow through one cross-section.
- · Speeds and flow rates are magnitudes along one flow direction.
Explore in the Lab
Carry this section and flow rate into the Bernoulli & Energy Lab
The Lab keeps one flow rate for the whole path and derives every station speed from it.
Technical reference
A = π D² / 4
A = w h
Q = A V
ṁ = ρ Q
- A
- flow area of the cross-section[m²]
- V
- mean speed over the section[m/s]
- Q
- volumetric flow rate[m³/s]
- ṁ
- mass flow rate[kg/s]
The area is the flow area actually available to the fluid. A partly full duct is not this calculation.
V is a mean speed. Turning a measured centreline speed into a mean speed is a profile question, not a continuity one.
The mass flow rate assumes the stated density is the density of the fluid passing this section.