Does a given volume of water at 1 atmosphere of pressure differ significantly in any way from the same volume of water from the deep parts of the world. Like the water in that trench everyone keeps talking about?
Like, assuming I could handle the pressure, would I notice a difference if I were swimming at 20 feet from when I swim at, say Chellenger deep (36,000 feet)?
Under 1125 atmospheres, the density of water would go up to about 1.05 g/cc.
Compressibility.
I don’t follow you…do you mean do you notice a physical sensation from being in water that is greater than 1 ATM?
Yeah. Like from the compression of the water–would it be noticably more dense. Or would it change in some other way that I’m not thinking of.
So that’s an increase in density approximately twice as big as the difference in density between fresh and sea water. So you’d feel more buoyant, well, actually, you wouldn’t - because the water in your body would be similarly compressed, so it would just feel normal.
I don’t think a 5% increase in density would make a noticeable difference to the sensation of swimming.
At 36,000 feet below the surface, there would be a change in the viscosity of sea water. The change in viscosity would, in turn, affect how you swam.
The kinematic viscosity can be expressed in terms of the dynamic viscosity and the density. The viscous behavior of the fluid around the swimmer can be expressed as a Reynolds number. As described below:
So, let’s assume that you’re swimming at the bottom of the Challenger Deep. The density of water is, as computed by Squink, 1.05 g/cc. It’s going to be very cold down there - let’s assume the temperature is indistinguishable from 0. That gives us a dynamic viscosity of 1.787 centipoise. Converting units, we have the kinematic viscosity equal to (1.78700 * (0.001 (Pa * s))) / (1 050 (kg / (m^3))) = 1.70190476 × 10-6 m^2 / s.
Using Gettelfinger’s assumptions, the resulting Reynolds number is 371,616.29.
According to their paper, it takes a 1000-fold change in viscosity to have any significant effect. When swimming equally at a depth of 20 ft, where the density is 1030 kg/m^3, the Reynolds number is 364,537.883. A change? Certainly. A significant change? Probably not. Salinity gradients would probably have a much bigger impact.