k-Wave

1. s148275
   

   Member
   Joined: Mar '20
   Posts: 15

   I am a bit confused about the equation that needs to be used for the heating rate Q. From my simulation I get the outputs: sensor_data.p, sensor_data.ux_non_staggered and sensor_data.uy_non_staggered. The following code is used to get the average intensity:
   

   ux_sgt = fourierShift(sensor_data.ux_non_staggered, 1/2)
   uy_sgt = fourierShift(sensor_data.uy_non_staggered, 1/2)
   Ix = sensor_data.p .* ux_sgt
   Iy = sensor_data.p .* uy_sgt
   I = sqrt(Ix^2+Iy^2)
   I_avg = mean(I, ndims(I))

   If I want to find the heat deposition Q, what is the equation that I need to use? For now I am using:
   

   alpha_np = db2neper(alpha_coeff_p_db,alpha_power) ...
   * (2 * pi * f0).^alpha_power;
   Q = alpha_np .* I_avg;

   However, sometimes Q=2*alpha_np*I_avg is used. What is the case here and why?

   Thanks in advance!

   Posted 2 years ago #

2. bencox
   

   Developer
   Joined: Mar '10
   Posts: 292

   Hi s148275,

   You could output the intensity directly using sensor.record = {'I_avg'} or ... = {'I'}. The 2 comes from the fact that the absorption coefficient for intensity is twice the pressure absorption coefficient (which is the one usually quoted) when they are given in Nepers/m.

   Interestingly, they are the same if given in dB/m as the definition of the decibel for the intensity uses 10log_10 and for the pressure is 20log_10.

   Best wishes
   Ben

   Posted 2 years ago #

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