ONE FORMULA, ONE ANSWER
Rayleigh Number Calculator
Calculate the Rayleigh number for a specified natural-convection configuration. Choose input units and calculate one value within the stated conditions.
Inputs
Calculations run in this browser. Scientific notation such as 1.2e-3 is supported. Do not group thousands.
Result
Rayleigh number Ra
Enter values and select Calculate.
Ra = gβΔT L³/(να)
Assumptions
Required: positive inputs, properties at a common reference state, and L and ΔT appropriate to the geometry. Boussinesq approximation with small βΔT. Geometry-specific thresholds, correlations and convection classification are excluded. This app additionally restricts βΔT≤0.1.
Displayed values are floating-point approximations. Design safety factors and unprovided error contributions are not calculated.
Formula references and credits
NaNa Lab created the code, descriptions, icons and preview images. Text, figures and code from the linked references have not been reproduced.
Physical constants: NIST / CODATA 2022. The values of μ₀ and ε₀ are measured recommendations, not exact defining constants. Values and precision notes are in the source record.
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