Simulations & Solvers

FDTD, Low-Frequency, Neuron, Mode-Matching, Flow, Acoustics, etc...

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  • FDTD, Low-Frequency, Neuron, Mode-Matching, Flow, Acoustics, etc...

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    27 Posts

    Hi! Can someone help me understand if it makes sense to calculate SAR statistics in a low frequency electrical stimulation (30 Hz)? Thanks!!

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    By default, Sim4Life tries to use all available resources to start as many simulations as you submit or have cores or GPUs available. The first simulation usually starts fine, and the rest fail due to insufficient licenses.

    You have the option to limit the number of simultaneous simulations in the ARES tool. Please change the Resource Management Option from Concurrent Jobs to One Job at a time as in the attached screenshot.

    Ares3.jpg

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    Thank you for the great explanation.

  • Cannot place line as a voltage sensor

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  • run two simulations on the same computer

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    Hey there!
    That's a pretty powerful setup with dual GPUs! To run two simulations at the same time, you can utilize parallel computing techniques to distribute the workload across both GPUs. Since you already know how to designate GPUs for each simulation, you might want to explore frameworks like CUDA or OpenMP, which are excellent for managing parallel tasks. Ensure that your simulation software is configured to support multi-GPU operations and check its documentation for any specific settings related to concurrent simulations. Sometimes, fine-tuning the job scheduling can also help in managing simultaneous tasks more effectively.
    On another note, if you're interested in staying ahead with technology, check out Quantum AI. They delve into the fascinating world of quantum computing, which has the potential to transform simulation and problem-solving in groundbreaking ways. Best of luck with your simulations!

  • Impedance of tissue

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    @brown
    Thank you, I will check these things. Additionally, there are some warning messages which may help:
    7427af6d-b388-4d9a-b629-2678e1872293-image.png
    Is the mesh division not precise enough?

  • Running iSolve on GPU

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    You definitely have enough memory here. It's likely that the solver could not use the device for some other reason. Can you try updating your graphics drivers?

  • Fields data extraction after MQS simulation

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    Thanks for your reply

  • Grid Setting

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    I think you can change how the steps change between gridlines with the grading option. If you have some entities that should not influence the grid set priority to zero (for those entities). Then choose the largest grid step you want for the global settings and and the smallest (0.5mm) for the arrays_grid. You should manage to control how the grid changes away from the arrays_grid.

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    When using a long line as "normal" edge source, the discretization will result in one edge being the actual source and rest of the line being discretized as PEC filament. This can lead (depending on the excitation frequency, the length of the source line and the setup) to inaccuracies due to the additional capacitance introduced be the PEC filaments. An alternative that is, in most cases, a more accurate source representation is using the "Distribute Along Line" option, the source is equally distributed over all the discretized edges of a line element (see image, right). That prevents any PEC filaments and therefore makes the injection of the signal more realistic.

    Time delay = distance between the transmitter and receiver*sin(theta)/c where theta is the angle of antenna. I would suggest looking into antenna array literature for theoretical background on calculating this quantity.

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    If you click on Network Analysis in your Analysis tree, what is your Reference Impedance?

    It is set to 50 ohms by default, but you have change it based on the Input Impedance for the coil before plotting the S11 curve.

    Plot the complex Input Impedance. At resonance, the imaginary part will be zero (the circuit is purely resistive). So at the desired resonant mode / frequency, you should find the corresponding real value, and set this value as the reference impedance to plot |S11|.
    image.png
    6f536c46-f9f2-4d5a-b787-cfdb97521404-image.png
    5730b440-37ea-4190-824e-1fac4e45155a-image.png

  • Cannot run tutorial

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    Thank you very much. This fixed the issue. This was related to Ares also.

  • Convergence Level in S4L

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    A simulation can end in a couple different cases: If the specified level of convergence is reached, or if the specified number of periods are simulated. In the case of that tutorial, the simulation is set to run for 15 periods, and so it ended before a -50 dB convergence was reached. Convergence is a spectrum, and the level of convergence required for a given application is up to the user's discretion.

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    Thanks Ofi. How can I fix this or is this something I need to account for?

  • tutorial not running

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  • FDFD solver tutorials

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  • Thermal external input file

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  • Modeling Ferrite in an FDTD Simulation

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    Hi @arc Please check "Console" window (open it via menu VIEW | Console if it is not open) to see what kind of error you are getting. The reason for failed simulation might be related to something else. You can easily test with an existing tutorial example. For example,

    open Dipole Antenna Tutorial, model a rectangular brick next to the dipole, clone one of the existing simulation settings and drag&drop this new brick into the simulation set its material such that rel/ Permeability o 1e4 generate grid, voxel and run to see if it also fails
    I hope it helps.
  • Python API for Debye dispersive model

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    Yes,

    You need to import XMaterials and specify the material model to be linear dispersive, as in the following example (which should be easy to extend), where parameters for one Debye pole are assigned.

    import XMaterials as xm # Adding a new MaterialSettings material_settings = emfdtd.MaterialSettings() material_settings.ElectricProps.MaterialModel = material_settings.ElectricProps.MaterialModel.enum.LinearDispersive # Specify settings for dispersive poles material_settings.raw.ElectricDispersiveSettings.StartFrequency = 10.e6 material_settings.raw.ElectricDispersiveSettings.EndFrequency = 100000.e6 material_settings.raw.ElectricDispersiveSettings.Conductivity = 0. material_settings.raw.ElectricDispersiveSettings.Permittivity = 11.098 debye_pole_01 = xm.LinearDispersionPole() debye_pole_01.Active = True debye_pole_01.Type = xm.LinearDispersionPole.ePoleType.kDebye debye_pole_01[xm.LinearDispersionPole.ePoleProperty.kDebyeAmplitude] = 1.0 debye_pole_01[xm.LinearDispersionPole.ePoleProperty.kDebyeStaticPermittivity] = 22.67 debye_pole_01[xm.LinearDispersionPole.ePoleProperty.kDebyeInfinityPermittivity] = 11.098 debye_pole_01[xm.LinearDispersionPole.ePoleProperty.kDebyeDamping] = 3.234e-11 # Add dispersive poles to the Linear Electric Dispersion Viewer material_settings.raw.ElectricDispersiveSettings.Poles = [debye_pole_01]
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    I suspect that this is because the grid from your LF simulation does not match the grid that you use in your isotropic and anisotropic simulations.

    The isotropic simulation runs fine because it does not use your cache file.

    The anisotropic simulation has stored those conductivity values expecting a specific grid.

    Try right clicking on the grid settings folder in the simulation from which you are creating your anisotropy tensor, select "Copy Grid Configuration", then "Paste Grid Configuration" on the anisotropic simulation.

    If you want to include features in your anisotropic simulation that you don't don't want to have simulated in your initial LF simulation, you can still include include objects in your initial simulation so that they are considered for the gridding without assigning them material properties, using them as a boundary condition or voxeling them. Just drag the object directly into the grid settings folder. That way your grid can always match.