Acoustics simulation: Getting wrong pressure distribution and magnitude due to a monopole source in



I am doing a very basic problem in simcenter with acoustic solver.

I have a monopole source with amplitude 1( real 1, imag 0) at origin and acoustic field upto radius 10 times the wavelength. freq is 1000 Hz and air density and speed of sound.

Now from theory and physics, as I calculate pressure away from source it's magnitude should be magnitude at source ( taken 1 here as load) divided by distance from source. But the results I am getting are very wierd. My results are as follows:

1. I placed three microphones at radial distance 6 ,8 and 9.5 times wavelength. Let it be mic A, B and C resp.

But my Acoustic pressure at C is max than A and than B. Whereas from theory it should be A>B>C. 

2. Also the pressure magitude should be simply Amplitude/radial distance, which is also not matching with simulation result. Simulation result is very very less than theoretical.

At C pressure should be 0.3095Pa but it is coming as 0.002315 Pa.

Attached microphone pressure results and spl distribution on outer surface (which should ideally be same as radial distance is same but simulation results are different).