凑合反推法──流体力学变分原理建立的一条新途径

SEMI-INVERSE METHOD─A NEW APPROACH TO ESTABLISHING VARIATIONAL PRINCIPLES FOR FLUID MECHANICS

凑合反推法是刘商联系统方法[1]的进一步发展，应用这种方法可以方便地构造各种亚广义变分原理及广义变分原理，并可以消除临界变分现象．对于任何二维守恒型流体力学方程，作者推导得到了其广义变分通用公式．几个实例证明这种方法是有效的、简单的，并具有普遍的意义．

Semi-inverse method, an extension of Liu's systematic method[1], is proposed to establish various sub-generalized variational principles and generalized variational principles in fluid mechanics. The novel method can completely eliminate variational crisis (some Lagrange multipliers are equal to zero). Furthermore a universal variational formulation for two dimensional fluid mechanics has been obtained. Some illustrative examples are given to testify the effectiveness and simplicity and universal validity of the method.