A well-insulated LNG (Liquefied Natural Gas) tank is a key facility in a regasification terminal. The management of Boil off Gas (BOG) produced from a LNG storage tank due to heat leak from the surrounding is an important issue. Many small-scale experimental studies have been reported on evaporation-condensation of different volatile liquids. However, these studies cannot mimic the behaviour of an industrial process. Computational Fluid Dynamics (CFD) simulation is the preferred alternative to study boiling phenomena at a large scale. However, no such study exists for LNG. A comprehensive dynamic CFD model presented in this study for an onshore full-scale LNG storage tank is a maiden attempt to fill that gap. We carry out a thorough investigation of internal flow dynamics and heat transfer characteristics owing to free convection. Our work provides insights on the boiling phenomena and allows reliable quantification of BOG production. © 2018 Elsevier B.V.