Complex Engineering Systems - Modeling and Optimization offers an in-depth exploration of the foundational principles, advanced methodologies, and interdisciplinary applications essential for understanding and managing intricate engineering systems. Spanning mathematical modeling, numerical simulation, optimization strategies, and AI-assisted techniques, the book presents a rich blend of theory and real-world problem-solving tools. This comprehensive volume is tailored for researchers, professionals, and graduate students engaged in engineering, applied mathematics, and computational sciences.Covering diverse themes-from system-of-systems behavior and multiphysics modeling to nanofluid dynamics, fractional heat transfer, queuing theory, and machine learning integration - the chapters collectively emphasize the interplay between complexity, adaptability, and innovation. The contributors shed light on modern challenges like cryogenic flow analysis, pressure sensing in microfluidics, MHD flow behavior, and AI-driven predictive modeling.