Musical instruments that start with the letter I include the igil, ipu, Irish uillean, Irish bouzouki, ichigenkin, inci, iya, itotele and istarski mih. The instruments originate from countries ranging from Cuba and Ireland to Croatia, Japan and the Philippines.
Bessel's functions are often used in acoustics for describing circular membranes behaviour (exploited by most of the musical instruments). They are the solutions of the wave equations using polar coordinates. Set the properties of the membrane Bessel's functions describe the vibrational modes of the membrane.
The Neuman well function depends on transmissivity, storativity, distance from pumping well to observational well, time, specific yield of the aquifer, anisotropy of the aquifer, and ratio of the thickness of the aquifer and the distance between the pumping and observation wells.