Understand the engineering model
What is Flow Continuity?
Fluid and aerodynamic models connect density, pressure, flow, velocity, geometry, viscosity, gas state, and coefficient-based forces while preserving the stated control volume and reference conditions.
Turn a flow rate and geometry into the average velocities visitors need without duplicating trade-specific pipe sizing.
The relationship
Write the model before substituting values
Q=Av; circular A=πD²/4. For steady incompressible flow, A₁v₁=A₂v₂.
See the calculation
From measurement to engineering result
1Fluid state and geometry2Continuity or energy model3Flow, pressure, or force
Worked context
Read the output with its units
0.01 m³/s through a 100 mm circular section has average velocity about 1.273 m/s; at 50 mm it is about 5.093 m/s.
Interpret with care
Important model boundary
This kinematic continuity model assumes steady incompressible flow and uses average section velocity. It does not calculate friction, pressure loss, pump performance, compressibility, profile effects, or pipe suitability.
A calculated value does not certify a component, material, installation, operating envelope, code requirement, or safety decision. Check measurements, signs, standards, uncertainty, and professional approval where consequences matter.
Browse Engineering & science for connected physical relationships.
Quick guide
How to use this calculator
- Choose the physical relationship and solve direction that match the known measurements rather than forcing unlike quantities into one formula.
- Enter every unit, sign, reference direction, geometry, material property, fluid property, temperature basis, coefficient, and idealization explicitly. The calculator normalizes compatible quantities internally and exposes intermediate values.
- Use reconciliation and companion outputs to catch entry mistakes, then retain the stated model boundary. A theoretical result is not a design approval, material certificate, equipment rating, or safety determination.
Calculation method
How the flow continuity calculator works
Turn a flow rate and geometry into the average velocities visitors need without duplicating trade-specific pipe sizing.
Q=Av; circular A=πD²/4. For steady incompressible flow, A₁v₁=A₂v₂.
Worked example
Flow Continuity example
0.01 m³/s through a 100 mm circular section has average velocity about 1.273 m/s; at 50 mm it is about 5.093 m/s.
Q=Av; circular A=πD²/4. For steady incompressible flow, A₁v₁=A₂v₂.
Supported inputs
Precision and limits
Engineering-model boundary
This kinematic continuity model assumes steady incompressible flow and uses average section velocity. It does not calculate friction, pressure loss, pump performance, compressibility, profile effects, or pipe suitability.
Units and precision
Calculations normalize compatible inputs to SI, retain working precision, and round only for display. Very small and large nonzero values use scientific notation; displayed digits cannot create accuracy beyond the entered measurements and properties.
Decision boundary
This page solves the declared idealized relationship only. Verify applicable material data, operating conditions, geometry, loads, coefficients, standards, codes, manufacturer requirements, uncertainty, and professional approval before consequential use.
Category ownership
Generic mechanics, materials, fluid, aerodynamic, wave, and thermodynamic relationships live here. Trade-specific pipe, HVAC, motor, electrical, construction, automotive, radiation, statistical, chemical, and astronomical workflows remain with their established categories.
Privacy
Entered values and results stay in this browser and are not sent to analytics or third parties.
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