Comparative Analysis of Control Structures in Core Annular Flow Systems: A CFD Simulation Study

This paper investigates the application of two distinct control structures, conventional single-layer control and cascade control, in a Core Annular Flow (CAF) system simulated through Computational Fluid Dynamics (CFD). Both control strategies were tested and carried out open-loop tests to tune the controllers following the SIMC rules. Results demonstrate that both structures, one I controller for the oil fraction and one cascade controller PI -I for the velocity ratio and the oil fraction, successfully controlled the system, each exhibiting unique behaviors and performance characteristics. The analysis highlights the strengths and limitations of each approach, where the single-layer structure with an I controller was faster to reach the setpoint and was efficient to reject disturbances. Copyright (c) 2025 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)