#heat-transfer

Convective heat-transfer dimensionless numbers as an API, computed locally and deterministically. The prandtl endpoint computes the Prandtl number Pr = μ·cp/k (or ν/α), the ratio of momentum to thermal diffusivity that sets the relative thickness of the velocity and thermal boundary layers — air is about 0.71 and water about 7 at 20 °C. The grashof endpoint computes the Grashof number Gr = g·β·|ΔT|·L³/ν², buoyancy versus viscous forces in natural convection (for an ideal gas the thermal-expansion coefficient β ≈ 1/T). The rayleigh endpoint gives the Rayleigh number Ra = Gr·Pr, either from Gr and Pr or from the full natural-convection inputs, which governs the onset of convection (critical ≈ 1708 for a heated horizontal layer). The peclet endpoint computes the Péclet number Pe = Re·Pr = v·L/α, advection versus diffusion of heat. The biot endpoint computes the Biot number Bi = h·L/k and flags whether the lumped-capacitance transient model applies (Bi < 0.1). All inputs are SI. Everything is computed locally and deterministically, so it is instant and private. Ideal for thermal-engineering, HVAC, electronics-cooling, CFD, process-engineering and heat-transfer-education app developers, natural-convection and transient-conduction tools, and simulation software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. These are convective heat-transfer groups; for the Reynolds number alone use a Reynolds API and for surface-tension numbers a Weber API.

api.oanor.com/prandtl-api

Newton's law of cooling and convective heat transfer as an API, computed locally and deterministically. The convection endpoint applies the convective-heat-transfer rate Q = h·A·ΔT — the heat carried away from a surface equals the convection coefficient times the area times the temperature difference between the surface and the fluid — and solves for whichever of the heat rate, the coefficient, the area or the temperature difference you leave out, with typical coefficients for natural and forced air, water, boiling and condensing built in. The cooling endpoint applies Newton's law of cooling, T(t) = T_env + (T0 − T_env)·e^(−k·t): from an initial temperature, the ambient temperature and a cooling constant (or time constant τ = 1/k) it gives the temperature after a time, or the time to reach a target temperature, or it solves the cooling constant from a measured temperature at a known time — the maths behind how a hot drink, a forensic body or a cooling casting approaches room temperature. The coefficient endpoint links the cooling constant to the physical properties, k = h·A/(m·c), and the thermal time constant. Everything is computed locally and deterministically, so it is instant and private. Ideal for thermal-engineering and HVAC tools, food-safety and forensic cooling apps, electronics-cooling and process-control software, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is convection and transient cooling; for steady conduction through walls use a U-value API and for thermal radiation use a Stefan-Boltzmann API.

api.oanor.com/cooling-api