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Using interpolation functions to define material properties
Posted Sep 17, 2014, 1:20 p.m. EDT RF & Microwave Engineering, Heat Transfer & Phase Change, Geometry, Materials, Mesh 2 Replies
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The following example from the model library models absorbed radiation in the human head:
www.comsol.com/model/absorbed-radiation-sar-in-the-human-brain-2190
Rather than directly representing each subdomain of the human head (probably because that'd be very difficult to mesh, or because such a geometry model was not readily available) this model utilizes one geometric domain for the entire head and then applies an interpolation function with data from a text file to specify the variation of material properties throughout the head.
I have not tried this approach before, but interpolating material properties like this seems iffy to me. You'd need to make your mesh small enough throughout the entire domain to make sure that all of the material variations will be captured. This sacrifices one of the main advantages of FEA, which is the ability to mesh different domains with different resolutions. If you're resorting to a uniform mesh throughout a variable domain, then wouldn't you be better off just using FDTD or FDFD?
Does anyone have any thoughts/references for the use of interpolation functions to define material properties in FEA, and the resultant accuracy of the FEA?
Thank you.
Kevin
P.S. I cannot actually view the referenced SAR comsol model directly because it utilizes the bioheat transfer interface which I don't have, but I re-created enough of the model to get an idea of what it is doing. I may be looking to model something similar.
www.comsol.com/model/absorbed-radiation-sar-in-the-human-brain-2190
Rather than directly representing each subdomain of the human head (probably because that'd be very difficult to mesh, or because such a geometry model was not readily available) this model utilizes one geometric domain for the entire head and then applies an interpolation function with data from a text file to specify the variation of material properties throughout the head.
I have not tried this approach before, but interpolating material properties like this seems iffy to me. You'd need to make your mesh small enough throughout the entire domain to make sure that all of the material variations will be captured. This sacrifices one of the main advantages of FEA, which is the ability to mesh different domains with different resolutions. If you're resorting to a uniform mesh throughout a variable domain, then wouldn't you be better off just using FDTD or FDFD?
Does anyone have any thoughts/references for the use of interpolation functions to define material properties in FEA, and the resultant accuracy of the FEA?
Thank you.
Kevin
P.S. I cannot actually view the referenced SAR comsol model directly because it utilizes the bioheat transfer interface which I don't have, but I re-created enough of the model to get an idea of what it is doing. I may be looking to model something similar.
2 Replies Last Post Mar 12, 2015, 5:29 a.m. EDT
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Posted:
1 decade ago
Without having looked into the specific model one reason may be to specify a continuous profile of the material property which is not possible by using domains.
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Posted:
10 years ago
Hi,
Do you know how to get the text file that you are talking about? In the comsol reference it is given that we can get it from MRI data. Do you have any idea on that?
Thanks
Do you know how to get the text file that you are talking about? In the comsol reference it is given that we can get it from MRI data. Do you have any idea on that?
Thanks