http://www.k-wave.org/forum/topic/thermo-acoustic-simulation-with-annular-transducer Support for the k-Wave MATLAB toolbox en-US Thu, 14 May 2026 00:03:58 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/thermo-acoustic-simulation-with-annular-transducer#post-9177 Thu, 06 Feb 2025 11:24:57 +0000 Crispi99 9177@http://www.k-wave.org/forum/ <p>Hi Brad, hi community,<br /> I'm simulating the thermo-acoustic field of an annular transducer, in a heterogeneous medium (a water tank and a small piece of fat in the focal region, in order to evaluate the thermal lesion). The source pressure is 175 kPa, the frequency is 1.5 MHz. The problem is that I obtain an extremely high (wrong) field of temperature, up to 1000 °C with a heating period of 5 s. I obtain a max intensity of 4691.1406 W/cm^2 and a max heat volume rate Q of 1212.9214 W/cm^3. Thus, maybe Q is excessive but I cannot explain why. This is the formula that I have considered:</p> <p>alpha_np = db2neper(medium.alpha_coeff, medium.alpha_power) .* (2 * pi * freq).^medium.alpha_power;<br /> Q = alpha_np .* amp.^2 ./ (medium.density .* medium.sound_speed);</p> <p>Briefly, these are some parameters that I'm considering: </p> <p>% water medium parameters<br /> c0 = 1500; % sound speed [m/s]<br /> rho0 = 1000; % density [kg/m^3]<br /> BonA = 5.2; % non linear parameter of the medium (B over A)<br /> alpha_0 = 0; % frequency-dependent absorption coefficient<br /> alpha_y = 2; % power-law exponent of water</p> <p>% tissue medium parameters (fat tissue)<br /> c0_t = 1450; % sound speed of tissue [m/s]<br /> rho0_t = 911; % density of tissue [kg/m^3]<br /> BonA_t = 10; % non linear parameter of tissue (B over A)<br /> alpha_0_t = 0.6; % frequency-dependent absorption coefficient of tissue [dB/cm*MHz]<br /> alpha_y_t = 1.0861; % power-law exponent of tissue</p> <p>axial_size = 100e-3; % total grid size in the axial dimension [m]<br /> lateral_size = 120e-3; % total grid size in the lateral dimension [m]<br /> x_tissue = 30e-3; % tissue dimension along x coordinate [m]<br /> y_tissue = 120e-3; % tissue dimension along y coordinate [m]<br /> z_tissue = 120e-3; % tissue dimension along z coordinate [m]<br /> distance_t = 70e-3; % tissue distance from the transducer external surface [m]</p> <p>% thermal parameters<br /> T0 = 20; % water initial temperature [°C]<br /> thermal_conductivity = 0.6045; % water thermal conductivity [W/(m.K)]<br /> specific_heat = 4178; % water specific heat [J/(kg.K)]<br /> T0_t = 20; % tissue initial temperature [°C]<br /> thermal_conductivity_t = 0.211; % tissue thermal conductivity [W/(m.K)]<br /> specific_heat_t = 2348.33; % tissue specific heat [J/(kg.K)]<br /> on_time = 5; % source on time [s]<br /> off_time = 20; % source off time [s]<br /> dt_thermal = 0.1; % time step size of thermal simulation</p> <p>I thank you in advance for your attention! </p>