先进材料疑固实验室 Heat transfer Laboratory of Advanced Materials Solidification Fourier's Law of thermal conduction Temperature distribution in a substance can be: T=f(x,y,z,r) For a continuous substance: dT= 正也 Or ay 02 aonoAdaicehaeiasSdicaio 上降文通大学 SHANGHAI JIAO TONG UNIVERSTTYHeat transfer Fourier’s Law of thermal conduction Temperature distribution in a substance can be: T  f x, y,z,  For a continuous substance: f  , y, ,  dz T dy T dx T d T dT          dz z dy y dx x dT d          