Mach number is based on the local speed of sound and velocity no? Can you confirm the calculation that the mach no is above 0.3?
You do bring up a good point, but I would still say compressible flow simulations are notoriously annoying to get right and the result differences for flow that is less than 0.5 mach is not significant enough to warrant the extra complexity in dealing with compressible flow. You would usually only need that kind of accuracy if you validating a solver against a benchmark. So do consider the trade offs vs the possible increased accuracy. @ROHIT_SR
Thanks @Retsam for pointing that out. Yes, it should be disabled. Try that first @ROHIT_SR before setting a ramping inlet. Retsam also correctly pointed out that the flow progression should be linear. There was a user facing this issue and it was mentioned that if you set the differences in values for velocity too high, the solver will interpolate these values and dramatically increase the flow velocity in a way that defeats the purpose of using a ramping inlet in the first place. Again, try this only after you have attempted a run with potentialfoam disabled.