Heat generation rate and Heat transfer rate in a MQS/Thermal simulation

[Lys]

Hello,

I need to know the type of heat generation rate and heat transfer rate in a MQS/thermal simulation, is it: 'None', 'Constant', Linear(t), Linear(T)??
I used the IT'S database to define the parameters but I need to set the type as well.
As I read in bibliography most mention it is not linear, in this case should it be Constant or None?

Regards

[brown]

Do you have any more details about what you are simulating? The model you use depends on your scenario and on what tissue or material you are simulating. If you assigned a material from the database using 'Assign Materials', then each of those values will have a default value that for many cases is sufficient.

[Lys]

Dear Brown,
The model I use is a mouse model with 52 tissues, in the database all tissues mostly have the parameters of thermal conductivity, heat capacity, heat transfer rate and heat generation rate.
Later in the thermal simulation it is written the type for heat rate transfer and heat generation rate ('None', 'Constant', Linear(t), Linear(T)).
this is not done automatically it is up to the user to choose, so I need to know when we irradiate a mouse model to radiofrequency wave which type is needed to choose?

[halder]

In terms of the material settings in the thermal simulation:
The heat transfer rate defines whether heat removal by perfusion should be considered. In the absence of this term, heat is only removed by thermal conduction (diffusion) and boundary conditions. The options provided for heat transfer rate affect whether perfusion is constant or affected by local thermoregulation (temperature (T) dependent perfusion, e.g., to account for vasodilation). As for the heat transfer rate, the heat generation rate term can be constant or affected by local thermoregulation (T dependent, reflecting increased metabolic activity with increasing temperature). It is also possible to introduce time-dependent heat generation, e.g., to model a heating battery.
Baseline perfusion values (incl. variability information) are available in the IT'IS database and can be automatically assigned from sim4life: (http://www.itis.ethz.ch/virtual-population/tissue-properties/database/database-summary/).
If non-constant perfusion should be applied or not depends on the tissue and temperature increase magnitude (e.g., muscle above 39 starts to have a strong perfusion increase). The conservativeness of a perfusion model choice is application-dependent.

To simulate the heating effect of tissues over time, blood perfusion and heat generation rate (metabolic heat generation) of the tissue would also need to be considered. The perfusion is covered in the option "Heat Transfer Rate". All options that you can enter here are related to heat-transfer based removal of energy from the system. Perfusion can be adjusted by changing the type of hear transfer (None, Constant, Linear (T), Piecewise Linear (T).

The constant term assumes constant perfusion, independent of tissue temperature. It is the default assigned when using the IT'IS tissue database in Sim4Life. Linear (T) or Piecewise Linear (T) assume temperature dependent perfusion. You can add your your transition temperatures using the little "+" icon. Please note that the linear coefficients represent the slope of the linear perfusion. Each transition temperature indicates the change of the perfusion rate.
For example, if you wish to enter constant perfusion up to 37 degrees, linear perfusion of 10 times the "standard" perfusion rate between 37 and 43 degrees, and constant perfusion above 43 degrees, then you would enter:
transition temperatures: [37,44], linear coefficients: [10,0].