Reynolds Number Heat⚠ unverified
Physics / Heat Transfer · Compute the Reynolds number for a heat transfer flow
Parameters
| Input | Symbol | Unit | Default | Description |
|---|---|---|---|---|
| rho | ρ | kg/m**3 | 1.0 | Fluid density |
| U | U | m/s | 1.0 | Flow velocity |
| L | L | m | 1.0 | Characteristic length |
| mu | μ | Pa*s | 1.0 | Dynamic viscosity of the fluid |
| Output | Symbol | Unit | Description |
|---|---|---|---|
| result | Re | — | Reynolds number (dimensionless). Returns 0.0 when mu is not positive |
The science & history
Understanding the Parameters
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$\rho U L/\mu$ — inertia/viscous forces; laminar/turbulent transition depends on geometry (e.g. pipe $\mathrm{Re}_D \sim 2300$).
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Pair with Pr to get Nu from correlations.
Derivation (Approaching a Proof)
Identical to the fluids derivation: nondimensional Navier–Stokes produces Re. See Reynolds Number.
History
Osborne Reynolds; heat-transfer correlations are almost always written in Re–Pr (or Gr–Pr) form.
Related Concepts: Reynolds Number, Nusselt Number, Prandtl Number, Grashof Number
Notes: Registry calculator reynolds-number-heat (unverified). Same physics as fluids Re card.