Below are the questions asked during the event, along with their respective answers.
Q: Can you solve a BCI-ROM for steady-state conditions?
A: Yes, the BCI-ROM is applicable to both steady-state and transient analysis.
Q: How does the CFD mesh affect the accuracy of the BCI-ROM?
A: It depends on what you mean by accuracy. A perfect BCI-ROM will exactly match the CFD results, however, we know that the CFD results accuracy is very much influenced by the CFD mesh. The concepts of ensuring grid-independent results, and calibrating your Simcenter Flotherm model with Simcenter T3Ster measurements are certainly considered as best practice prior to creating the BCI-ROM.
Q: With real-life heat sinks, I often see HTC levels of 10,000 to 50,000 W/m²K at the surface of devices. And even more with liquid cooling. Do you have results that show how good your methodology is over this broader range?
A: The second application example shown during the webinar produced a BCI-ROM accurate over a range of 1-100,000 W/m²K. The validation document accessible with Simcenter Flotherm has several validation examples included. They explore accuracy for various HTC ranges: 1-100, 1-1000, 1-10,000, 1-100,000 and 1-1,000,000 W/m²K.
Q: In one of your examples, you applied HTC to 6 faces. Can you break out the faces into multiple surfaces (for example, like the 64 ‘surfaces’ of a Rubik’s cube, instead of just 6)?
A: Yes. The extraction time is affected by the number of HTC faces but there is no hard limitation to the number of faces specified prior to extraction.
Q: How many CFD cases do you have to run to get the ROM?
A: Zero. The BCI-ROM extraction process uses the Simcenter Flotherm mesh, geometry, and attributes but is a separate solver to the CFD solver.
Q: To prove BCI the range for HTC 1-1000 W/m²K seems far too small to me, as we proved in the DELPHI project 25 years ago, we miss spray cooling, heat pipes, normal jet impingement etc., all important for IGBTs.
A: The exported BCI-ROM includes the range of HTC and accuracy required during the extraction process. It is important for the user to develop the BCI-ROM for all conceivable use cases.
Q: Looking ahead, will your tools (Simcenter Flotherm) be developed to include embedded BCI-ROM models?
A: This is a key part of ongoing Research and Development. We will announce a timeline to support this when the implementation is sufficiently evolved.