Compressibility Explained | Fluid Properties in Fluid Mechanics #shorts | Shubham Kola

Added: 2026-05-27

[00:00:00]The next term is compressibility.

[00:00:02]The compressibility is defined as the variation of volume or density with respect to pressure with constant mass.

[00:00:10]In simple words, compressibility is the measure of how much given volume changes instantaneously when placed under pressure.

[00:00:19]If variation of volume with respect to pressure is high, then compressibility is high.

[00:00:25]Mathematically, compressibility is defined as the reciprocal of bulk modulus of elasticity.

[00:00:32]Where bulk modulus is defined as the ratio of direct stress to volumetric strain.

[00:00:38]In fluid mechanics, the direct stress is hydrostatic stress.

[00:00:42]And volumetric strain is the ratio of change in volume to original volume.

[00:00:47]That is equal to - VDP upon DV.

[00:00:51]Here P is pressure and V is volume.

[00:00:54]Therefore, compressibility equal to 1 upon K.

[00:00:58]And after simplifying, this will get formula for compressibility, that is - DV upon V into DP.

[00:01:05]Here minus sign is needed to assure that an increase in applied external pressure will results a decrease in volume of object.

[00:01:13]The effect of pressure or change in volume in case of liquids is negligible.

[00:01:18]For this reason, water and other liquids are considered incompressible.

[00:01:23]While the gases are compressible.