nx_heat_transfer.nx

nx_heat_transfer.nx -- FOOD-SCIENCE SUITE / HEAT-TRANSFER PHYSICS rung. The transport physics behind thermal processing: conduction (Fourier), and the two dimensionless numbers that decide a retort process -- Biot Bi = h*Lc/k : Bi < 0.1 -> the food heats uniformly (lumped); Bi > 0.1 -> internal gradients, a COLD SPOT lags. Fourier Fo = alpha*t/Lc^2 : dimensionless heat-penetration time. These are exactly what says whether a can has a cold spot and how long heat takes to reach it -- the tie between the vessel/retort work and the preservation 12-D cook. INTEGER-EXACT. h in W/m^2.K; Lc (characteristic length) in mm; k as deci-W/m.K (x10, so water 0.6 = 6); thermal diffusivity alpha in centi-mm^2/s (x100, so food 0.14 = 14); results x1000 (milli). THE exceed: the cold-spot verdict (Biot) and penetration time (Fourier) are COMPUTED, not assumed -- a retort chart cannot tell you whether your pack even has a lumped or gradient thermal response. grounded: fourier_law_conduction + biot_number + fourier_number genealogy_id: heat_transfer_physics + nishi_food_science_suite