Computational fluid dynamics $($CFD$)$ is a powerful tool for simulating and analyzing fluid flow phenomena in civil engineering applications, such as water resources management, environmental modeling, and hydraulic infrastructure design. Investigate the theoretical foundations of CFD$,$ including numerical methods, turbulence modeling, and boundary conditions. How do engineers use theoretical models of CFD to simulate and predict fluid flow behavior, optimize hydraulic designs, and assess the performance of hydraulic structures under different flow conditions and operational scenarios?