For compressible flows with higher Mach numbers, operating pressure is less important. Since the pressure variations in these flows are significantly larger than those in low-Mach-number compressible flows, roundoff error is not a significant issue and gauge pressure is not really necessary. In fact, it is customary to perform these computations using absolute pressures. Just setting the operating pressure to zero will make gauge and absolute pressures equal as Ansys Fluent always utilises gauge pressure.

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