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William June 19, 2003 01:56

Cryosurgery modelling
Hi everyone, I would like ask some questions regarding the capabilities of FLUENT. I'm currently working on a project that requires me to use FLUENT to monitor the temperature distribution across a tumor with respect to time. My problem is that I do not know whether FLUENT is able to model a freezing problem with the following requirements:

1) properties of tumor need to change with respect to temperature

2) tumor has blood vessels in it, hence there is a need to incorporate 2 types of materials in my model, whereby the blood is a liquid and the tumor a solid.

3) I may need dynamic meshing for my problem, but I don't really know what dynamic meshing is actually used for. Hence, I need to clarify with someone who is familiar with usage of dynamic meshing.

4) There is something called a freezing front in my problem, which is the freezing layer that separate the frozen region from the unfrozen region. This freezing front moves across the unfrozen regions to freeze the tissue and blood vessels, and I need to monitor the temperature of this front with respect to time and space.

5) How do I change the fourier equation that FLUENT uses for heat transfer problems into a equation that I need? Do I need to write a C program to change it? Where can I get the information on how to do it?

I know the above questions may be a bit vague to some of you, but I do appreciate any help that you all can provide me. Thanks a lot.


ap June 20, 2003 14:20

Re: Cryosurgery modelling
I think you can model your problem (I find it really interesting, even if it doesn't strictly belong to my field) in FLUENT.

1) You can define variable properties using some pre defined formulation in the Define->Material window. If you don't find the formulation you need for your property function, you can implement it by a user defined function (UDF).

2) A first approximation of your model may be done considering vessels as holes which go through the mass of the tumor. You can easily create this mesh in Gambit. What's the form of the tumor?

3) Dynamic meshes are used to model objects which move, like a piston in an engine or a blade in a mixing vessel. I don't think you need them...but maybe I need more details.

4) How do you subtract heat from the tumor? Do you apply an object at a costant temperature, subract heat to blood or what? However, I think what you call freezing front is the local temperature profile on a section of the tumor. And you can read this directly using FLUENT postprocessing tools and monitor it during the calculation. You can also create an animation of temperature to see how it changes in time in your whole domain.

5) You can change equations solved by FLUENT using UDF. With UDF, you can also add other equations if you need it. See the UDF manual for this, however, yes, they are written in C :).

For heat transfer, you can do the "Modeling Periodic Flow and Heat Transfer" tutorial you find in the Tutorial Guide.

I hope this is of some help. And write if you need more.



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