CFD simulation of a hyperloop capsule inside a closed environment

One of the most restrictive conditions in ground transportation is traveling through a tunnel at high speed. In those conditions waves are propagated, increasing the pressure upstream the object, and so, the drag compared to the open flow case. Although this drawback is mitigated with larger tunnels, another proposed solution is to decrease the pressure inside the tunnel. In this paper it is demonstrated that the drag coefficient is almost invariant with the pressure conditions. This effect allows, not only to have smaller tunnels with respect to the existing for standard trains, but also to enhance the speed of the train without increasing its aerodynamic losses.