Effects of Viscosity

There are many situations where we are interested in the sound field in the vicinity of small objects. This often requires us to account for the viscosity of the medium. This greatly complicates the relationship between fluid velocity near solid obstacles and the fluctuating pressure. In the following, the differential equations for acoustic fluctuations in a viscous fluid are presented. Obtaining solutions to these equations can provide endless challenges. Here we solve them for some specialized situations that are relevant for acoustic sensing.