Development of cost-effective CFD modeling techniques for transient missions of hyperloop vehicles

Hyperloop system represents a promising alternative to the conventional means of transportation to face the critical environmental situation. Unfortunately, CFD modeling of hyperloop transient missions with a standard overset approach presents a high computational effort. This work aims to develop a methodology that reduces the cost of modeling a simplified pod with a three-phase operation: acceleration, cruise and deceleration. Firstly, a comparison between an overset domain and one employing Non-Reflecting Boundary Conditions (NRBCs) is conducted, resulting in a halving of the computational time and obtaining deviations of just 2.4% in vehicle drag. However, the larger reduction in cost comes with the development of an equivalent quasi-steady state configuration for hyperloop systems. The leading contribution of this paper is that the proposed approach considers the effect of the induced mass flow generated by the effect of moving a pod inside a tube, a non-negligible effect. Such a novel method helps reduce the error in terms of drag coefficient, which can achieve values higher than 40% if the boundary conditions for the steady state are not properly corrected. Consequently, the proposed method reduces simulations cost up to 35 times with an average error of only the 4% in power requirement predictions.