SEFT simulation - problems with parameters

I am currently doing some focused ultrasound simulation. The goal being to reach a precise part into the brain. I did your tutorial which worked fine but now I would like to change a bit the SEFT parameters.

I wanted to reproduce a transducer where I have the curvature radius, the aperture width and the focal depth which are 3 different values. I know how to change the 2 first but then when I remove parametrization of the SEFT to be able to move the focus it doesn't keep my exact values. How should I do that ?

And I have a some other questions:

  • Is it possible to measure (and after visualize) the intensity over the time for my simulation?
  • What is the difference between the setup frequency and the Environment Operating frequency?

Thanks for the help !

  1. I don't understand the question. You can change the curvature radius and aperture in the GUI. The point created in the SEFT model corresponds to the geometric focus (essentially the curvature radius), this is not the focal depth. You'd need to run the simulation to figure out where the max will be or use some analytic formula.

  2. In Sensors in simulation you should be able to toggle from 'Frequency' to 'Frequency and Time Domain Recording' and then you can select how many snapshots you want to record and from what time to what time

  3. Setup frequency is the sinusoidal frequency at which the source is excited.

@montanaro The setup frequency and the environment operating frequency should be the same? (I found that these two frequencies are the same and set as 110 KHz in the tutorial)
What is the impact on simulation results if the setting is different?

I don't know what environment and operating refers to. The simulation frequency refers to the source signal from the transducer (I assume this is what you mean with operating frequency) ... I don't know what environment frequency is, maybe you mean the frequency at which the output is evaluated?

The default acoustic solver (LAPWE) solves a linear equation, therefore a source pulse at a given frequency will give you an output oscillating at the same given frequency. The output of the acoustic solver is the magnitude of the pressure at that oscillation.

If you want to look at the energy content for other frequencies you will need to use a nonlinear solver and materials would then need to have some nonlinear properties. Typically you don't need this, but it depends on what physical phenomena you're interested in modeling.

@montanaro Sorry for the misunderstanding.

The environment operating frequency was setting in the SEFT parameters. (SEFT is in the Explore window)

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Setup frequency was in the 「Setup」

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