Concurrent DASSL Applied to Dynamic Distillation Column Simulation

Abstract

The accurate, high-speed solution of systems of ordinary differential-algebraic equations (DAE’s) of low index is of great importance in chemical, electrical and other engineering disciplines. Petzold’s Fortran-based DASSL is the most widely used sequential code for solving DAE’s. We have devised and implemented a completely new C code, Concurrent DASSL, specifically for multicomputers and patterned on DASSL. In this work, we address the issues of data distribution and the performance of the overall algorithm, rather than just that of individual steps. Concurrent DASSL is designed as an open, application-independent environment below which linear algebra algorithms may be added in addition to standard support for dense and sparse algorithms. The user may furthermore attach explicit data interconversions between the main computational steps, or choose compromise distributions. A “problem formulator” (simulation layer) must be constructed above Concurrent DASSL, for any specific problem domain. We indicate performance for a particular chemical engineering application, a sequence of coupled distillation columns. Future efforts are cited in conclusion.