This article addresses the hypersonic flow of nitrogen as the test gas over the double-wedge in high-enthalpy, free-stream conditions. It elaborates on the significance of gas models by modeling them as the calorically perfect and thermally perfect gas. The unsteady results with these gas models match qualitatively with the experimental schlieren images during the initial flow development; however, they begin to differ as the simulation nears the experimental end time. The calorically perfect gas model results deviate significantly compared to the experimental visualization. We attribute this discrepancy to the assumption of a two-dimensional flow field in which span-wise relaxation of the flow is absent. Despite these assumptions, we obtain the average wall heat-flux distribution within the experimental uncertainty. The peak value’s location is sensitive to the gas models used in this numerical campaign, and the thermally perfect gas model best predicts the experimental results.