Digital simulation is one of the modern technologies that has contributed significantly to the development of aircraft design. It enables engineers to study an aircraft’s aerodynamic performance virtually before manufacturing it and conducting practical tests. This technology relies on Computational Fluid Dynamics (CFD), which uses mathematical equations and computer software to analyze airflow around wings, the aircraft fuselage, and various other components. This helps engineers understand airflow behavior and identify the forces acting on an aircraft during flight. The simulation process begins with creating a three-dimensional aircraft model using engineering design software. The surrounding flow domain is then divided into a large number of small cells, forming what is known as a Computational Mesh. The governing equations of fluid motion, including the equations for conservation of mass and momentum, as well as energy when necessary, are subsequently applied to calculate the distribution of velocity, pressure, and temperature around the aircraft components. These results help identify regions of high and low pressure, analyze airflow over the wings, and investigate how lift is generated and how aerodynamic drag affects flight efficiency. This technology is particularly important in wing design, as engineers can test different airfoil shapes and vary the angle of attack and flight speed to determine their effects on aerodynamic performance. Simulation also enables the study of airflow separation from the wing surface, which can lead to a reduction in lift and cause an aerodynamic stall. Furthermore, CFD can be used to analyze how the design of the aircraft nose, fuselage, and tail components affects aerodynamic drag, helping engineers improve aerodynamic efficiency and reduce fuel consumption. One of the major advantages of Computational Fluid Dynamics is that it reduces the need to manufacture multiple models for preliminary testing, thereby saving time and costs during the design stages. It also allows engineers to compare numerous design alternatives and identify the most suitable configuration before proceeding to wind tunnel testing or testing physical prototypes. However, the accuracy of the results depends on the quality of the computational model, the mesh, the physical assumptions, and the simulation settings. Therefore, the results must be validated and compared with experimental data and practical test results. With continuous advances in computing power and artificial intelligence, simulation techniques have become increasingly capable of handling complex problems and analyzing large amounts of data in shorter periods. These technologies represent essential tools for developing more efficient and safer aircraft by improving wing designs, reducing aerodynamic drag, and evaluating different operating conditions before an aircraft is built. Consequently, Computational Fluid Dynamics has become an important link between theoretical design and engineering applications, giving engineers the opportunity to test ideas digitally and improve them before transforming them into real aircraft. Assist. Lecturer Al-Buraq Haider Mohsen