Abstract
In many aerospace computer simulations, the system of differential equations to be integrated numerically is of the stiff variety, where there may be widely disparate effective time constants corresponding to the different components of behavior being simulated. In such a situation, traditional, explicit methods (such as Runge-Kutta, etc.) may not always perform well, owing to the stability requirements of the stiff system. In such a case, certain specially designed implicit methods may be appropriate, but they require considerably more storage and computation and more sophisticated computer programs. To alleviate these problems, the authors have previously developed several simple explicit integration procedures with enhanced stability properties. These methods are useful for many stiff problems, but they have the disadvantage of a relatively low order of accuracy. A method which combines enhanced stability with third- order accuracy is presented. This is accomplished at the price of certain additional derivative evaluations. The new procedure is tested on some typical stiff problems, and comparisons are made to the traditional nonstiff RK2 method and to the other explicit stiff methods previously developed by the authors. (I.E.)