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Can not assign sine voltage in time domain study for tissue RF ablation problem.

Posted 2024年5月22日 GMT-4 04:57 Version 6.1 4 Replies

Abid Hussain
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I am working on RF ablation problem. When I assign V =V0 in decimal number I am getting scars and damage tissue. But when I add sine function to electric potential than my system not working as intended.
What could be the reason?
I want to add 30*sin(2*pi*48000*t).
I attach the pictures below, I can not attach COMSOL file because of the file size limit.

4 Replies Last Post 2024年5月23日 GMT-4 16:19
Henrik Sönnerlind COMSOL Employee

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Posted: 10 months ago 2024年5月22日 GMT-4 08:36

Something is not right with the physics and modeling here. If your frequnecy is 48 kHz, then you need a time step in the order of 1 microsecond to resolve each period. It will be difficult to run an analysis for 120 seconds, since that would require > 100 million time steps.

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Henrik Sönnerlind
COMSOL
Something is not right with the physics and modeling here. If your frequnecy is 48 kHz, then you need a time step in the order of 1 microsecond to resolve each period. It will be difficult to run an analysis for 120 seconds, since that would require > 100 million time steps.
Abid Hussain
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Posted: 10 months ago 2024年5月22日 GMT-4 21:23

Something is not right with the physics and modeling here. If your frequnecy is 48 kHz, then you need a time step in the order of 1 microsecond to resolve each period. It will be difficult to run an analysis for 120 seconds, since that would require > 100 million time steps.

Thanks, I got your point. I changed the time step to 100ms and frequency to 5 Hz, now I am getting the voltage graph (I was just checking the output). You mentioned that 120s and 48KHz setting is hard to get. What does this mean, are you talking about the computational cost? If I want to mimic RF ablation, which runs on 480KHz, then, what will be optimal setting?

Thanks in advance.

>Something is not right with the physics and modeling here. If your frequnecy is 48 kHz, then you need a time step in the order of 1 microsecond to resolve each period. It will be difficult to run an analysis for 120 seconds, since that would require > 100 million time steps. Thanks, I got your point. I changed the time step to 100ms and frequency to 5 Hz, now I am getting the voltage graph (I was just checking the output). You mentioned that 120s and 48KHz setting is hard to get. What does this mean, are you talking about the computational cost? If I want to mimic RF ablation, which runs on 480KHz, then, what will be optimal setting? Thanks in advance.
Mark Harradine
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Posted: 10 months ago 2024年5月23日 GMT-4 01:58

Some blog articles that may help:

https://www.comsol.com/blogs/modeling-periodic-electric-signals-and-their-thermal-effects

https://www.comsol.com/blogs/study-radiofrequency-tissue-ablation-using-simulation

https://www.comsol.com/blogs/modeling-thermal-ablation-for-material-removal

Some blog articles that may help: https://www.comsol.com/blogs/modeling-periodic-electric-signals-and-their-thermal-effects https://www.comsol.com/blogs/study-radiofrequency-tissue-ablation-using-simulation https://www.comsol.com/blogs/modeling-thermal-ablation-for-material-removal
Dave Greve
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Posted: 10 months ago 2024年5月23日 GMT-4 16:19

The frequency-transient analysis step mentioned in the second article cited by Mark may well be appropriate. This depends on whether the time dependence of the heating within a cycle is material to the problem.

Such an approach is commonly used for RF heating where the RF frequency is MHz and the heat transport problem takes place over seconds.

The frequency-transient analysis step mentioned in the second article cited by Mark may well be appropriate. This depends on whether the time dependence of the heating within a cycle is material to the problem. Such an approach is commonly used for RF heating where the RF frequency is MHz and the heat transport problem takes place over seconds.

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