Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture Baba G. Agaie, Ilyas Khan, Ali Saleh Alshomrani and Aisha M. Alqahtani Eur. Phys. J. Plus, 132 5 (2017) 234 Published online: 25 May 2017 DOI: 10.1140/epjp/i2017-11435-7