For a stationary disk, the air pressure on the platter is atmospheric pressure. For a disk spinning at 10,000 RPM, say 140 miles per hour for a 5.25 inch disk, I assume the Bernoulli effect would reduce the pressure, but because of the Ekman flow, the pressure would be more than the pressure would be on a non-rotating disk in which the air was moving over the disk surface linearly at 120 miles per hour. The so-called no-slip property of gas-solid interfaces requires that the gas in the immediate vicinity of a spinning disk move with the disk. Unlike the solid comprising the disk, however, the gas spinning with the disk cannot withstand the concomitant centrifugal force. The resulting outward spiraling flow is called Ekman flow. Can you give me an approximate estimate of the percentage of atmospheric pressure a spinning disk platter at 10,000 RPM would "experience"?