先进材料疑固实验室 Momentum transfer Laboratory of Advanced Materials Solidification For a hexahedron,according to the Newton's 2nd law ma ∑F 人p杂空(p杂台+pfdk -气+pjdk Du ma,=pdxdydz D H pd G P- p+ 1 op dx 20r 2 0x Du =f 1 ap Dt p ax B X 之a人通大学 SHANGHAI JIAO TONG UNIVERSITYMomentum transfer For a hexahedron, according to the Newton’s 2nd law