Nusselt Number⚠ unverified
Physics / Heat Transfer · Compute the Nusselt number
Parameters
| Input | Symbol | Unit | Default | Description |
|---|---|---|---|---|
| h | h | — | 1.0 | Convective heat transfer coefficient, in watts per square metre-kelvin (W/(m**2*K)) |
| L | L | m | 1.0 | Characteristic length |
| k | k | — | 1.0 | Thermal conductivity of the fluid, in watts per metre-kelvin (W/(m*K)) |
| Output | Symbol | Unit | Description |
|---|---|---|---|
| result | Nu | — | Nusselt number (dimensionless). Returns 0.0 when k is not positive |
The science & history
Understanding the Parameters
-
$h$, $L$, $k$ — Nu $= 1$ would mean heat transfer no better than conduction through a stagnant fluid layer of thickness $L$.
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Distinct from Bi, which uses solid $k$.
- Registry may label $h$, $k$ dimensionless — use correct SI units.
Derivation (Approaching a Proof)
Definition: $\mathrm{Nu} \equiv hL/k_{\mathrm{fluid}}$. From nondimensional energy equation, wall temperature gradient relates to Nu.
History
Wilhelm Nusselt; Nu correlations are the workhorse of convective design.
Related Concepts: Biot Number, Reynolds Number Heat, Prandtl Number, Convection Heat Transfer
Notes: Registry calculator nusselt-number (unverified). Fluid $k$.