Learning Forum

[Sung ki Son]

I am writing to you today to ask for your help with a Joule heating simulation I am working on. I have successfully simulated the heating, but I need to verify the simulation by calculating the electrical conductivity over time. The conductivity value is not given in the monitor report, so I will need to use the Fields Calculator.

Under the Vector Commands, there is a command called " conductivity (cond) σ" which represents the electrical conductivity. However, I am not sure how to use this command to create a formula for calculating the electrical conductivity over time.

Would you please be able to help me with this? 

I would be grateful if you could provide me with some guidance on how to proceed with the formulation.

 

Thank you for your time and consideration.

[Ivonne Marti]

Hello Sung ki,

In Icepak, the Electrical Conductivity is an input, not a result. Could you please explain us in a different way what do you want to do?

Thank you.

[Sung ki Son]

Hi Ivonne ,

Thank you for you prompt reply, recently there was verification code problem with Ansys so i couldn’t reply early.  Regarding my question of electrical conductivity in field calculator I need to check this value inorder to verify the calculation method in Ansys icepak. therefore I am writing to bring to your attention some issues I have encountered during joule heating simulations using Ansys Icepak. As a licensed user of AEDT in Korea, I have been in communication with CAE specialized company of Ansys in Korea, regarding this complex issue. However, it seems that obtaining a timely response would be challenging as the issue is complex, and our deadlines are fast approaching. Therefore, I am reaching out to you directly in the hopes of expediting the resolution process.

 

 

 

After several months of analysis, it has become apparent that conducting a transient joule heating analysis with the Ansys Icepak software in a two-way coupling with either Q3D or Maxwell is not feasible due to limitations in the methodology. Consequently, the most viable option is to utilize the joule heating built-in module within Icepak.

 

 

 

While examining the joule heating transient results, I have identified discrepancies, particularly in the behavior of the EM Loss values in relation to the expected outcomes based on the thermal modifier. To ensure the accuracy of our simulation process, it is crucial that we review the entire simulation procedure in detail. By carefully examining the process, we can identify potential problem areas and determine whether the issue lies in the simulation setup or if it is related to the governing equation.

 

During the simulations, we have identified several discrepancies that require further investigation and clarification. I kindly request your expertise and assistance in resolving these issues. The points of concern are outlined below:

 

In order to verify the simulation, I have considered a simple copper wire with a rectangular shape. Since our hand calculation focuses solely on the heat generated by the copper wire, I have included an insulator in the Icepak simulation to limit heat loss and allow for a comparison between the temperature obtained from Icepak and the hand calculation.

 

 

Thermal modifier

 

I performed resistance and EM Loss analysis using Q3D at various temperatures, and the results demonstrate a strong agreement between our approach and Q3D. As it is shown once the temperature goes over than 467°C the thermal modifier coeff is constant therefore a horizontal line is appeared.

 

 

Q3D + Icepak (one way coupling, No Thermal Modifier)

In this simulation, without any thermal modification, the temperature reached at 1 second is 467°C in the hand calculation and 437°C in Q3D + Icepak (one-way coupling). Additionally, it indicates that there is agreement between the power dissipation calculated by Elentec and Q3D.

 

 

 

Icepak (Joule Heating, No Thermal Modifier)

In this simulation, without any thermal modification, the temperature recorded at 1 second is 467°C in the hand calculation and 454°C in Icepak (Joule heating). Additionally, there appears to be a discrepancy in the power dissipation when comparing the results to those obtained from Q3D. The power is lower than Q3D however the final temperature is higher than previous simulation, Why?

 

 

 

 

Icepak (Joule Heating, With Thermal Modifier)

In this simulation, involving thermal modification, the temperature achieved at 1 second is 964°C through hand calculation and 1291°C using Icepak (Joule heating, with thermal modifier). According to the thermal modifier, when the temperature reaches 426.7°C, the thermal modifier is set to 0.391. As a result, the power should remain constant for temperatures above 426.7°C. However, it appears that the power continues to rise regardless of the thermal modifier. Ansys should provide a precise explanation of the governing equation employed in Joule heating and how the thermal modifier aligns with this equation.

 

 

 

 

Comparison of Results – Without Thermal Modifier:

 

The power dissipation values in Icepak do not align with those obtained by Elentec and Q3D. Furthermore, we have observed that the last temperature in Icepak Joule heating is higher than that in Q3D+Icepak (one-way coupling), despite the power dissipation in Icepak Joule heating being lower than in Q3D+Icepak (one-way coupling). We seek an explanation for these inconsistencies and clarification regarding the accuracy of the power dissipation values.

 

 

 

Comparison of Results – With Thermal Modifier:

 

The power dissipation in Icepak does not adhere to the thermal modifier dataset. We kindly request a detailed explanation and investigation into this matter to ensure the accurate implementation of the thermal modifier.

 

 

 

Besides, I would like to ask about the unit of the following formulation used in joule heating simulation with Icepak in transient mode:

 

Integrate(Volume(Rectangle1), Joule_Heating_Density)

 

 

As you know, Icepak does not provide the unit for this formulation. However, I understand that the unit of Joule heating density in Ansys is “irrad_W_per_m2″. This means that the unit of Joule heating density is watts per square meter (W/m^2).

 

 

If we integrate a quantity with units of W/m^2 over a volume, is the resulting unit watts (W)? It sounds the unit would be W/m^3 isnt it?

 

 

 

We understand the complexities involved in simulation and analysis, and we greatly appreciate your expertise in addressing these discrepancies. Clear explanations and insights into the governing equations employed in the Joule heating simulation will be invaluable in resolving these issues and ensuring the accuracy of our results.

Thank you.