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Interpolation of material property inside domain

Posted 3 juin 2019, 07:25 UTC−4 Electromagnetics, Low-Frequency Electromagnetics, LiveLink for MATLAB Version 5.0 4 Replies

Nitish Katoch
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Hello everyone

I am looking forward to do tDCS human brain modelling where I will interpolate measured conductivity information of brain using MRI into human head model in COMSOL 5.0. I have prepared the mesh using simpleware and can solve the laplacian equation using literature values of conductivity. Now I want to interpolate personalized conducitivity values inside brain. The measured conductivity is with voxel size of 2mm and total of 30slices acquired within brain region only, whereas model data is of istropic 1 mm voxel which is used to make segemented model. What is the way of interpolate this conductivity information into the model. As data is of specific domain. Looking forward for healthy guidance.

4 Replies Last Post 10 juin 2019, 00:16 UTC−4
Edgar J. Kaiser Certified Consultant
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Posted: 6 years ago 3 juin 2019, 07:43 UTC−4
Updated: 6 years ago 3 juin 2019, 07:43 UTC−4

Hi,

you may want to check the documentation about the 3D interpolation function. This allows to use spatially distributed material properties.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi, you may want to check the documentation about the 3D interpolation function. This allows to use spatially distributed material properties. Cheers Edgar
Nitish Katoch
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Posted: 6 years ago 7 juin 2019, 06:00 UTC−4

Hi Kaiser

I have checked the documentation and prepared my import file accordingly. So is there any way I can check the cordinates of import file with the geometry. The problem is model data and measured domain data is with different resolution. Even if I upsample the data according to the model but still I am getting this error.

Undefined variable. - Variable: sigma11 - Geometry: geom1 - Domain: 32 Failed to evaluate variable. - Variable: comp1.ec.sigmaxx - Defined as: sigma11 Failed to evaluate variable. - Variable: comp1.ec.Jix - Defined as: (((comp1.ec.sigmaxxcomp1.ec.Ex)+(comp1.ec.Eycomp1.ec.sigmaxy))+(comp1.ec.Ezcomp1.ec.sigmaxz)) Failed to evaluate variable. - Variable: comp1.ec.Jx - Defined as: comp1.ec.Jix Failed to evaluate expression. - Expression: d(((comp1.ec.Jxtest(comp1.Vx)+comp1.ec.Jytest(comp1.Vy)+comp1.ec.Jztest(comp1.Vz))comp1.ec.d)(dvol),{test@4})

The domain 32 is white matter and sigma11 is the first row first column of tensor matrix. Please let me know if you have any further suggestion or need any information. I feel its not difficult but can't able to connect dots.

TIA

Nitish

Hi Kaiser I have checked the documentation and prepared my import file accordingly. So is there any way I can check the cordinates of import file with the geometry. The problem is model data and measured domain data is with different resolution. Even if I upsample the data according to the model but still I am getting this error. Undefined variable. - Variable: sigma11 - Geometry: geom1 - Domain: 32 Failed to evaluate variable. - Variable: comp1.ec.sigmaxx - Defined as: sigma11 Failed to evaluate variable. - Variable: comp1.ec.Jix - Defined as: (((comp1.ec.sigmaxx*comp1.ec.Ex)+(comp1.ec.Ey*comp1.ec.sigmaxy))+(comp1.ec.Ez*comp1.ec.sigmaxz)) Failed to evaluate variable. - Variable: comp1.ec.Jx - Defined as: comp1.ec.Jix Failed to evaluate expression. - Expression: d(((comp1.ec.Jx*test(comp1.Vx)+comp1.ec.Jy*test(comp1.Vy)+comp1.ec.Jz*test(comp1.Vz))*comp1.ec.d)*(dvol),{test@4}) The domain 32 is white matter and sigma11 is the first row first column of tensor matrix. Please let me know if you have any further suggestion or need any information. I feel its not difficult but can't able to connect dots. TIA Nitish
Edgar J. Kaiser Certified Consultant
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Posted: 6 years ago 7 juin 2019, 12:01 UTC−4

Did you assign the interpolation function to the conductivity in the respective material node or in the physics node?

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Did you assign the interpolation function to the conductivity in the respective material node or in the physics node?
Nitish Katoch
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Posted: 6 years ago 10 juin 2019, 00:16 UTC−4

I assigned it in Physics node using the current conservation option.

So process I am using is firstly make a text file with 9 columns. The first 3 are coordinates and next six are the data. Define a global interpolation variable with 6 different function names inside it. Use the physics node of current conversation and assign the user defined anisotropic conductivity with the similar function names written in global interpolation variable.

I assigned it in Physics node using the current conservation option. So process I am using is firstly make a text file with 9 columns. The first 3 are coordinates and next six are the data. Define a global interpolation variable with 6 different function names inside it. Use the physics node of current conversation and assign the user defined anisotropic conductivity with the similar function names written in global interpolation variable.

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