Incoming links: Aspen HYSYS
Process Simulation Software FREE Download - Aspen Hysys versus DWSim | COCO by Jeferson Costa (2020)
Source. Jeferson, a Brazilian from Petrobras, is the creator of the open source DWSim software, and in this video he gives a quick demo of his software and compares it briefly to aspen HYSYS, which appears to be the golden paid reference implementation.