http://www.k-wave.org/forum/topic/doubts-converting-pressure-into-heat-deposition Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:40:08 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/doubts-converting-pressure-into-heat-deposition#post-8579 Wed, 13 Jul 2022 18:56:12 +0000 bencox 8579@http://www.k-wave.org/forum/ <p>Hi ganrielcathoud, </p> <p>That expression comes from 2*alpha*I_av where I is the time-averaged intensity. In a plane wave, which is a good approximation in many practical cases, such as at the focus of a transducer, I_av is related to the acoustic pressure by 0.5*p_max^2/(density*sound speed), where p_max incorporates the effect of the absorption on the wave amplitude.</p> <p>Going back a step, 2*alpha*I_av is the gradient of the average intensity: if the average intensity in a plane wave is decreasing, there must be energy being left behind. That is the energy that is being converted to heat.</p> <p>Look up some reviews on ultrasound therapy for more details on this.</p> <p>Best wishes<br /> Ben </p> http://www.k-wave.org/forum/topic/doubts-converting-pressure-into-heat-deposition#post-8565 Wed, 13 Jul 2022 14:51:26 +0000 gabrielcathoud 8565@http://www.k-wave.org/forum/ <p>I'm simulating the heating generated by the use of ultrasound in the brain. The ultrasound simulation is working fine, but I am having difficulties with the temperature simulation. How do I convert pressure aplied into deposited heat? I found a conversion here on the forum, but I don't understand why:</p> <p>source.Q = alpha_np.*sensor_data.p_max_all.^2./(medium.density .* medium.sound_speed);</p> <p>I appreciate any help.</p> <p>The whole temperatura simulation is:</p> <p>clear source;</p> <p>medium.thermal_conductivity = thermal_conductivity_water*ones(Nx,Ny);<br /> medium.thermal_conductivity(head_mask==1) = thermal_conductivity_bone;</p> <p>medium.specific_heat = specific_heat_water*ones(Nx,Ny);<br /> medium.specific_heat(head_mask==1) = specific_heat_bone;<br /> alpha_np = db2neper(medium.alpha_coeff, medium.alpha_power)...<br /> *(2 * pi * source_freq).^medium.alpha_power; </p> <p>dt = 0.001;</p> <p>source.Q = alpha_np.*sensor_data.p_max_all.^2./(medium.density .* medium.sound_speed);<br /> source.T0 = 37;</p> <p>input_args = {'PlotSim', true};</p> <p>kdiff = kWaveDiffusion(kgrid, medium, source, [], input_args{:});</p> <p>on_time = duration_of_stimulus; % [s]<br /> off_time = 60; % [s]</p> <p>kdiff.takeTimeStep(round(on_time / dt), dt);<br /> T1 = kdiff.T;</p> <p>kdiff.Q = 0;<br /> dt = 0.1;<br /> kdiff.takeTimeStep(round(off_time / dt), dt);<br /> T2 = kdiff.T; </p>