Comparisons of pressure ratio, at the at different pressure as a function of gas apex angle α As fig. demonstrated, π1 remain almost constant until 0.35 radian, then gradually reduce to less than 0.15 and after that, it goes up with the apex angle. At 7.5 atm, the π1 follows the same trend. At 11.5 - 15.5 atm pressures, π1 becomes constant and is not affected by the change of angles. As the pressure rises, the π1 remain constant until the 0.35 angle and then slightly rises at a higher apex angle.