f 500[Hz] Incident wave frequency T 1/f Incident wave period omega 2*pi*f Angular frequency lambda0 c0/f Wave length c0 343[m/s] Speed of sound k 2*pi/lambda0 Wave number L 20[mm] Probe tube length R 5[mm] Microphone casing radius H 5[mm] Probe tube volume height dr 1[mm] Pipe inner radius dw 0.3[mm] Pipe wall thickness D0 2*dr+2*dw Total pipe diameter kD0 k*D0 Wave number times tube diameter dvisc 0.22[mm]*sqrt(100[Hz]/f) Viscous boundary layer size dt 0.2*(L/10)/c0 Time step given by CLF condition