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Modeling endovascular ablation

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Hi,
I am trying to model endovascular ablation. I checked the video tutorial on tumor ablation, and used some tips from it, but in my case, I also have a laminar (blood) flow within the vessel.
My domains are very simple, a tube to model the vessel, with a spherical electrode in it, all surrounded by tissue.

I tried with Electric Current + Bioheat transfer (which has heat transfer in solids and in fluids) and I get a meaningful result, however this way I won't get the velocity and pressure pattern within the vessel. Adding Laminar Flow as a third physics for some reason does not work, it won't converge to a solution.

So I tried replacing the Bioheat transfer with Conjugated Heat Transfer (default model: Heat Transfer in Biological Tissue).
I added a Fluid, with viscous heating, an inlet (value of velocity) and outlet (no viscous pressure) on the artery, and an initial value of (laminar) velocity for the vessel (and 0 velocity in the tissue). I have also tried 0 velocity for all domains. Either way I get the same error (reported below).
For the Heat Source, I chose Total Power Dissipation Density on the whole domain except the electrode, which I set as "Heat Transfer in Solids".

The Electric Current is Stationary, while the Conjugated Heat is of course time dependent.

This is all identical to what I did for the Bioheat.
But for some reason the Conjugated Heat does not converge to a solution, and I get the error
"Repeated error test failures. May have reached a singularity.
Time : 0
Last time step is not converged."

If I disable the Fluid, then I get a solution, but since I need the velocity profile, I have to keep it enabled.

I can't really understand what I do wrong with the Fluid.
If anyone has any idea, I would greatly appreciate.
Thanks so much in advance!

Rossana

1 Reply Last Post Oct 7, 2016, 3:21 a.m. EDT
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Posted: 8 years ago Oct 7, 2016, 3:21 a.m. EDT

Hi,
I am trying to model endovascular ablation. I checked the video tutorial on tumor ablation, and used some tips from it, but in my case, I also have a laminar (blood) flow within the vessel.
My domains are very simple, a tube to model the vessel, with a spherical electrode in it, all surrounded by tissue.

I tried with Electric Current + Bioheat transfer (which has heat transfer in solids and in fluids) and I get a meaningful result, however this way I won't get the velocity and pressure pattern within the vessel. Adding Laminar Flow as a third physics for some reason does not work, it won't converge to a solution.

So I tried replacing the Bioheat transfer with Conjugated Heat Transfer (default model: Heat Transfer in Biological Tissue).
I added a Fluid, with viscous heating, an inlet (value of velocity) and outlet (no viscous pressure) on the artery, and an initial value of (laminar) velocity for the vessel (and 0 velocity in the tissue). I have also tried 0 velocity for all domains. Either way I get the same error (reported below).
For the Heat Source, I chose Total Power Dissipation Density on the whole domain except the electrode, which I set as "Heat Transfer in Solids".

The Electric Current is Stationary, while the Conjugated Heat is of course time dependent.

This is all identical to what I did for the Bioheat.
But for some reason the Conjugated Heat does not converge to a solution, and I get the error
"Repeated error test failures. May have reached a singularity.
Time : 0
Last time step is not converged."

If I disable the Fluid, then I get a solution, but since I need the velocity profile, I have to keep it enabled.

I can't really understand what I do wrong with the Fluid.
If anyone has any idea, I would greatly appreciate.
Thanks so much in advance!

Rossana


Hi, Rossana
Now, I also have a project about model endovascular ablation. And, also have problem same you. If you have finished this project, can you send to me the model? My email is "truongia.ntc@gmail.com"
It's really helpful to me. Thank you so much !!!
[QUOTE] Hi, I am trying to model endovascular ablation. I checked the video tutorial on tumor ablation, and used some tips from it, but in my case, I also have a laminar (blood) flow within the vessel. My domains are very simple, a tube to model the vessel, with a spherical electrode in it, all surrounded by tissue. I tried with Electric Current + Bioheat transfer (which has heat transfer in solids and in fluids) and I get a meaningful result, however this way I won't get the velocity and pressure pattern within the vessel. Adding Laminar Flow as a third physics for some reason does not work, it won't converge to a solution. So I tried replacing the Bioheat transfer with Conjugated Heat Transfer (default model: Heat Transfer in Biological Tissue). I added a Fluid, with viscous heating, an inlet (value of velocity) and outlet (no viscous pressure) on the artery, and an initial value of (laminar) velocity for the vessel (and 0 velocity in the tissue). I have also tried 0 velocity for all domains. Either way I get the same error (reported below). For the Heat Source, I chose Total Power Dissipation Density on the whole domain except the electrode, which I set as "Heat Transfer in Solids". The Electric Current is Stationary, while the Conjugated Heat is of course time dependent. This is all identical to what I did for the Bioheat. But for some reason the Conjugated Heat does not converge to a solution, and I get the error "Repeated error test failures. May have reached a singularity. Time : 0 Last time step is not converged." If I disable the Fluid, then I get a solution, but since I need the velocity profile, I have to keep it enabled. I can't really understand what I do wrong with the Fluid. If anyone has any idea, I would greatly appreciate. Thanks so much in advance! Rossana [/QUOTE] Hi, Rossana Now, I also have a project about model endovascular ablation. And, also have problem same you. If you have finished this project, can you send to me the model? My email is "truongia.ntc@gmail.com" It's really helpful to me. Thank you so much !!!

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