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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Time dependent pulse ultrasound wave

Posted 2017年1月24日 GMT-5 19:16 Acoustics & Vibrations, Studies & Solvers, Structural Mechanics Version 4.4 2 Replies

Hamed Rahimi
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Hi,

I have a time-dependent model to simulate ultrasound wave distribution.
My pulse function is "sin(2*pi*10^6*t)-step1(t[1/s])*sin(2*pi*10^6*t)" from t=0 to 0.001 and step function is 0 to 1 at 0.0002. Output is 200 micro-second of sine waves with 1 MHz frequency and then it turns off for the 800 microseconds.

I used 8 time steps for each sine wave and this increased the computation time significantly. When the study was done and I saved the file, the file was 50 GB!!! Is there a way to decrease the computation time? Am I doing something wrong?

Another question: Is there any way to solve this model in the frequency domain with a pulse like above? The pulse in the frequency domain will have a frequency of 1KHz. It means that one cycle per milli-second. Each cycle composed of 200 microseconds of sine waves and 800 micro-seconds of zero pulse.

Please see the model using link below (I shared it in my google drive).
drive.google.com/file/d/0B1tLRr6eAX6VQV9ZZjM4VEVkTHc/view?usp=sharing

Thanks,
2 Replies Last Post 2017年3月28日 GMT-4 08:00
Mads Herring Jensen COMSOL Employee

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Posted: 8 years ago 2017年1月27日 GMT-5 07:03
Hi Hamed

The times you enter in the Times section in the study step node have nothing to do with the internal time steps taken by the solver. These are only the times where you want the solution to be stored. To better resolve your problem numerically I suggest you do the following:

1) Add a study
2) Select Show Default Solver
3) Go to Solver Configurations > Solution 1 > Time Dependent Solver
4) Select and go to the Time Stepping section
5) Change to Steps taken by solver = Manual
6) Enter a time step that resolves your problem, for example, 1/(60*10^6) as your frequency is 10^6 Hz

To reduce the model size just set the Times where you need to visualize the solution. You can also use the selections in output. This is described at the bottom of this blog post: www.comsol.com/blogs/using-the-discontinuous-galerkin-method-to-model-linear-ultrasound/

... maybe the new Convected Wave Equation interface is of interest to you also.

Best regards
Mads
Hi Hamed The times you enter in the Times section in the study step node have nothing to do with the internal time steps taken by the solver. These are only the times where you want the solution to be stored. To better resolve your problem numerically I suggest you do the following: 1) Add a study 2) Select Show Default Solver 3) Go to Solver Configurations > Solution 1 > Time Dependent Solver 4) Select and go to the Time Stepping section 5) Change to Steps taken by solver = Manual 6) Enter a time step that resolves your problem, for example, 1/(60*10^6) as your frequency is 10^6 Hz To reduce the model size just set the Times where you need to visualize the solution. You can also use the selections in output. This is described at the bottom of this blog post: www.comsol.com/blogs/using-the-discontinuous-galerkin-method-to-model-linear-ultrasound/ ... maybe the new Convected Wave Equation interface is of interest to you also. Best regards Mads
Pengtao Huang
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Posted: 8 years ago 2017年3月28日 GMT-4 08:00
Hi, I'd like also to simulate a time dependent study in ultrasound wave, but i only have 4.4 version, i don't have "convected wave equation" fonction in my logistic, so could you help me find a model which is ultrasound wave model in 4.4 version?
Thanks
Hi, I'd like also to simulate a time dependent study in ultrasound wave, but i only have 4.4 version, i don't have "convected wave equation" fonction in my logistic, so could you help me find a model which is ultrasound wave model in 4.4 version? Thanks

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