I've noticed that unlike other liquids, when pouring olive oil for example, I don't hear any sound at all from it.
Usually you can hear an audible sound as a cup gets filled with water, as the sound increases in pitch.
What makes the oil behave this way?
Best Answer
The noise is generated by turbulent flow. Turbulence in the flow generates turbulence in the air at the interface between the air and the liquid surface, and that turbulence in the air is what we hear as the splashing sound.
So how much noise you hear depends on how turbulent the liquid flow is, and this is inversely related to the viscosity of the liquid. Turbulent flow is exceedingly hard to describe mathematically (indeed you can win a million dollars if you can do this) but as a general rule for a given flow rate the amount of turbulence decreases as the fluid viscosity increases.
And oil has a higher viscosity than water so when pouring oil into a cup we get less turbulence than when pouring water at the same rate, and hence we hear less noise.