Session: 3.5.1 - Coupled Multiphysics Simulation I

Paper Number: 157987

157987 - Enhanced Multiphysics Framework for ECM: Computational Modeling and Experimental Validation for Large Grid Deformations 

Abstract: 

Applying Computational Fluid Dynamics (CFD) to Electrochemical Machining (ECM) presents substantial challenges due to the complex interaction between electrochemical reactions—mainly hydrogen gas evolution—and the highly non-uniform flow field induced by Joule heating. In ECM, a high flow rate of electrolyte (e.g., NaCl or NaNO₃) is typically used to flush away reaction products and cool the workpiece surfaces. However, the small inter-electrode gap often leads to undesirable electric discharges resulting from gas generation. An alternative process, Pulse Electrochemical Machining (PECM), modulates the applied voltage and current in pulses. In PECM, anodic dissolution occurs during short current pulses, while the dissolution products are flushed away during the off-pulse period. Despite this advantage, PECM generally requires longer machining times than conventional ECM, highlighting the need for more effective ECM system designs. The design of ECM systems remains an iterative process where engineers must account for practical challenges such as electrolyte cooling, byproduct removal, and tool design. The strong coupling between electrodynamics and fluid dynamics largely drives the complexity of these challenges. From a computational perspective, modeling anodic dissolution and the relative motion between the tool and workpiece demands a comprehensive Multiphysics approach and a robust computational workflow. While Simcenter STAR-CCM+ provides a General Remeshing Model (GRM) suitable for ECM simulations, it struggles with maintaining mesh quality over time. This is due to poor representation of tessellated surfaces, which can lead to significant mesh degradation after several remeshing cycles, often resulting in artificial deformations and simulation instability.  To overcome these limitations, this study introduces a new simulation framework that integrates electrodynamics, multiphase flow, Joule heating, and new mesh morphing techniques to model anodic surface dissolution accurately. A key innovation is the development of an in-house algorithm that dynamically manages remeshing based on global mesh metric parameters, local mesh refinement, and adaptive time-stepping coupled with an Under-Relaxation Factor (URF) to stabilize simulations in Simcenter STAR-CCM+. This algorithm ensures that mesh quality is preserved during large deformations, improving computational stability and accuracy without excessive mesh refinement. Our framework successfully captures detailed fluid flow patterns and the evolution of the machining profile, with numerical predictions that closely match experimental results (with deviations in the range of 70-80 microns). These findings provide valuable insights into the ECM/PECM process and present new opportunities to optimize machining parameters, particularly in high-precision industries such as aerospace, automotive, and medical device manufacturing, where enhanced operational efficiency and superior surface quality are critical.

Presenting Author: Bashir Alnajar Corrdesa LLC

Presenting Author Biography: Dr. Bashir Alnajar specializes in multiphysics simulations, with a focus on computational fluid dynamics (CFD) and Computational Corrosion Analysis (CAA). He uses advanced numerical modeling techniques to solve complex challenges in biomedical engineering and electrochemical systems. His PhD research focused on modeling lipid-coated ultrasound contrast agent microbubbles to enhance targeted therapies. Dr. Alnajar currently works at Corrdesa LLC, where he addresses intricate electrochemical challenges such as corrosion, electrochemical machining, electroplating, and system optimization. In this role, he collaborates with leading industries, including aerospace and manufacturing, to develop innovative, data-driven solutions that improve system performance, efficiency, and reliability.