Giant planets likely acquire most of their mass through a circumplanetary disk (CPD) while embedded in the parent protoplanetary disk (PPD). It is expected that the CPD forms with gas flowing from the PPD nearly vertically, impinging the CPD itself as well as directly onto the gas giant’s atmosphere that forms an accretion shock, and the inner part of the CPD is connected to the planet via a boundary layer. The properties of the CPD, and the accretion shocks, are sensitive to thermal physics, and can deeply impact giant planet growth and its spin, as well as major observables, such as its thermal and H-alpha line emission. In this work, we present 2D (axisymmetric) viscous radiation hydrodynamic simulations of CPDs of accreting gas giants. We explore the thermal structure of the CPD as well as the accretion shock, study the angular momentum transport between the planet and the CPD at the boundary layer, and discuss potential observables such as H-alpha line emission.