Biot Number

Compare internal conduction resistance against external convection resistance.

visual calculatorHeat Transfer

Read the flow shape before trusting the number.

This page turns a CFD setup into regime, scale, and dominant-effect cues. Adjust the calculator below and compare the moving graphic with the computed result.

input scale

model

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Biotlumped capacitanceconduction

formula

KaTeX rendered

\begin{aligned}\text{Bi = h Lc / k\_s}\end{aligned}

ASCII source

Bi = h Lc / k_s

h (W/m^2/K)L_c (m)k_s (W/m/K)

0.0333

modeling note

lumped-capacitance valid

The classic rule of thumb is Bi < 0.1 for lumped-capacitance transients. Larger values mean spatial temperature gradients matter inside the solid.

Biot lumped capacitance conduction