Conservation of mass, second Newton's law, and momentum law are introduced into traffic flow to set up traffic continuity equation, Euler's equation, and momentum integral equation.

应用物理学中的质量守恒定律、牛顿第二定律、动量定律等，建立了交通流的连续性方程、欧拉方程和动量方程；

youdao

Because of the continuity of the flow, the stream function is introduced and it makes that the numbers of the fluid dynamical basic equation is cut off one.

由流动的连续性引进了流函数，使流体动力学基本方程的未知量的个数减少一个；

youdao