hi, regarding padding: as a general rule, if you are not sure whether a numerical parameter will affect your simulation results, the best course of action is to just "try and see". Change parameter -> see if it affects the results significantly. For the padding, you should try to increase it and check that your simulation results are not affected by spurious "boundary effects". as for tutorials: yes, in principle you should obtain the same results as shown in the manual. If you do not, please check carefully that you followed the steps faithfully (pay attention, for example, to the Normalization settings in the Analysis/postprocessing part, after extracting the field sensors - forgetting to tick this box would often lead to orders of magnitude difference in the results).

@Sylvain thanks for your reply! I did check with my supervisor and it is true that our license does not include that solver as our project does not need it.

Yes I did mean wavelength, not period .. That's the drawback of running high frequency simulations in FDTD, they require a lot of voxels ... If appropriate, try running it at 500 kHz and then update the automatic grid settings ... The auto grid settings is based on the material in your domain that has the lowest speed of sound, please remove air from the simulation domain if appropriate ... One of my previous comments tells you how to calculate the wavelength, the units and magnitude seem wrong in yours, remember that you're not using the speed of light to calculate the wavelength, you use the speed of sound in the medium (around 1500m/s)

What is the error message indicated by the red triangle? Maybe the flux is negative. Did you try adjusting the limits on the colorbar?

Hi, this typically happens if some material that is voxeled is not found. If I had to guess, I'd say that you have a source and no corresponding material (the source element should be in the Sources and Materials)

If I read the message correctly, it seems that another program is interfering. Have you tried to uninstall the Yale Neuron Solver?

@rose, you write "it was a bit different from the theoretical result", but unfortunately I don't fully understand what you did, what you are trying to do, and what you are comparing your results to. Perhaps if you describe (with e.g. screenshots and equations) both what you did and what the "theoretical results" I can try and find why they do not match.

Hi Javier, What error messages are you getting with Endring 1 simulation? I assume that you have already checked the tutorial "3.1.9 MRI Lowpass Volume Coil" which might help you to make sure that your setup is correct.

@rose see my answer here

See the Sim4Life Manual (2.6.1 EM LF - Simulation Theory) ωσμd2≪1^ The quasi-static conditions are sufficient conditions for the quasi-static approximation to hold. In practice, there are cases where the quasi-static approximation still yields accurate results even when the quasi-static conditions are not satisfied. The guideline for this type of cases is to compare to results from full-wave simulations. A table of the quasi-static approximation criteria for every simulation is written in the log file: Solid settings: frequency = x Hz, characteristic length (worst case domain diagonal) x Epsilon Mu SigmaE QS Approx. Quality Static Magn. Field SigmaE/wEpsilon Solid name The column QS Approx. Quality and Static Magn. Field refers to quasi-static conditions. The column SigmaE/wEpsilon indicates whether the displacement current ( ≪1 ) or the ohmic current dominates ( ≫1 ). 2.6.1.4 Choosing the Appropriate Low Frequency Solver has further details

Thank you @LJ and @Habib!! Fantastic explanations, I understand :)

@rose your simulations are most likely done with a 1V voltage at the excitation source (that's the default setting). This is perfectly fine from a numerical point of view, but in practice (e.g., if you wanted to compare with measurements) you probably want to normalize your results. In the Far Field Sensor, for example, you can normalize to a Total Available power of 1W (say). This way, you will be comparing apples to apples. That will not change the value for the Gain, though (since it is a power ratio, independent of scaling). This must come from either a difference in some aspect ratio of your dipole, or simply that you did not change the dimensions in the same proportion (1/10th) as you changed the frequency.

I would double-check that the electrodes being used are added as voxels correctly if they're not then the boundary conditions do not get set up properly. It might be easier to help if you provide more information.

@Sylvain It really helped!! I've successfully done making animation!! Thank you for helping me. Since you also gave me some advice about TRP problems, I would like to carry on the solutions you suggested. I really appreciate your help.

@habib Hi, Thank you for your reply. I can understand that if you enable the titration, the software keeps on scaling the field till sees a stimulation. But it also gives us a number for the scaling field. In this case, I am seeing that number to be 0.13. Doesn't it mean that the field has been scaled down to a factor of 0.13 to create the minimum field for stimulation - I was hoping that number to be orders of magnitude higher. Please correct me if I am wrong. Thanks for looking into this.

Hi, There is a tutorial called "Parallel Plates" for the LF (low-frequency) solver. I think it does exactly what you need. You can access the step-by-step instructions from Sim4Life -> Help -> HTML Tutorials -> 3.2.1. Parallel Plates You can also open the Sim4Life project using Sim4Life -> File -> Open Tutorial -> EM LF Tutorials -> Parallel Plates.smash