Time delays in dynamic simulation

Abstract A new algorithm for dealing with time delays in a dynamic process simulator is presented. This method uses past history arrays to store input variables, each time delay having its own array. The algorithm for updating the arrays and retrieving retarded values by interpolation is designed to provide consistent accuracy throughout the simulation. For maximum effectiveness the simulator should report and deal with the occurrence of discontinuous events and interpolation through such points should be avoided. The implementation of the algorithm in such a simulator and its application to liquid flow in pipes is described, together with examples which show how to calculate the number of array points required for a given accuracy if the characteristics of the input function are approximately known. Satisfactory functioning of the method is demonstrated.