resonance acoustical vs. electrical
 

Dear users,

i was modelling pressure wave propagation in compressible fluids using CFX and started with simple "one end closed pipe flows" of 1m lenght to figure out resonance frequencies.

To validate my numerical results or/and to setup the appropriate BC´s i was using simple fundamental equations.

I used 2 approaches to calculate the resonance frequency and find that there is a discrepancy of 1/2 pi.

1. "electrical resonance of LC-circuits"
=> omega = 1 / (L*C)^0,5

2. "wave equation of sinusoidal waves"
=> lambda = c / f

Only the second approach gives reasonable frequencies and the first was always 1/2pi to small.

Please take a look on the attached pdf.

best regards and thank you in advance :).