Abstract: For unsteady two-phase flows, the widely-used numerical approaches for solving continuity and momentum equations are fractional-step method and SIMPLE-family algorithms. The advantage of the fractional-step method is that the convergence rate is fast and the disadvantage is that the initial value problem is conditional stability. The SIMPLE-family algorithms are absolute stability for the initial value problem; however, their convergence rates are slow. For overcoming the disadvantage of the traditional SIMPLE-family algorithms, IDEAL algorithm is introduced in this paper. The convergence rates of SIMPLER and IDEAL are compared by two unsteady two-phase flow problems. It is found that IDEAL can enhance the convergence rate greatly, about 5~87 times over SIMPLER. Therefore, it can be concluded that IDEAL overcomes the disadvantages and combines the advantages of the fractional-step method and the SIMPLE-family algorithms.

Key words: two-phase flows, fractionalstep method, SIMPLEfamily algorithms, IDEALIDEAL

摘要： 对于非稳态两相流问题，联立求解连续性方程和动量方程最为广泛使用的方法为：分步方法和SIMPLE系列算法。分步方法的优点是：收敛速度快，缺点是：初值问题条件稳定。SIMPLE系列算法优点是：初值问题绝对稳定，缺点是：收敛速度慢。为了克服传统的SIMPLE系列算法收敛速度慢这一缺点，本文引入了IDEAL算法。本文通过2个非稳态的两相流问题对SIMPLER和IDEAL两种不同算法在收敛速度方面进行了比较。通过比较可以看出IDEAL算法的收敛速度较SIMPLER算法得到了大幅提高，提高了约6~87倍，克服了传统SIMPLE系列算法收敛速度较慢的缺点，同时具有了初值问题绝对稳定和收敛速度快这两个优点。

关键词: 两相流, 分步方法, SIMPLE系列算法, IDEAL算法