Carbon dioxide flows in a 50-mm-diameter pipe at a velocity of \(1.5 \mathrm{~m} / \mathrm{s}\), temperature \(66^{\circ} \mathrm{C}\), and absolute pressure \(50 \mathrm{kPa}\). Is the flow laminar or turbulent? If the temperature is lowered to \(30^{\circ} \mathrm{C}\), what is the flow regime? If the pressure is reduced to \(20 \mathrm{kPa}\), what is the flow regime? Explain the differences in answers in terms of the physical mechanisms involved.