Numerical simulation of Airflow Properties of the NACA 6420 Airfoil Using the Transition RANS k-ε Model - Oluwaseyi O. ALABI; Saidat A. SALISU; Oyeyemi T. AFOROLAGBA -BALOGUN; Temitope A. LADIGBOLU; Ayotunde O. FASINA; Anas BALA (Al-Bāhir)