FLOWORKS Accuracy

[baazar]

To All,

I'm going to post this on Solidworks forum as well but I figured I should try here too.
We recently purchased Floworks and are using it to thermally model an electronics project. Before we start using it for any projections on this design, we're testing its accuracy on small experiments.

Right now I've got a 3 Ω resistor burning 3 Watts attached to a heatsink. I've entered heat generation, thermal resistance (measured and calculated), ambient air conditions etc.
I'm quite sure I have all of the initial conditions as close to reality as possible.
Unfortunately I cannot get the results to get any closer than 10°C below what I am physically measuring (Calc = 40°C, Meas = 30°C).

Have any of you guys gotten floworks to produce highly accurate results (i.e. ±2.5°C) or is it always off or is there some major variable that is easy to miss that would influence the results?

Thanks in advance - Bram

 

[academix]

Hello:

The problem sounds interesting. We have had good experience in correlation of the kind stated, with SolidWorks Flow Simulation. Maybe you can send me a model that I can investigate and provide feedback,

Natarajan Ramamoorthy
Design Engineering Consultant

http://www.egsindia.com

 

[baazar]

So I've been doing some experimentation and I've gotten much closer to real results.

Playing around with contact resistance (as measured), air-flow (as assumed), and turning on things like gravity and radiation calculations have all contributed to more accurate results.

Unfortunately the two most influential attributes are the contact resistance and air flow. Contact resistance must be measured first since nearly all real-life junctions are not found in tables, and air flow which is assumed because it is difficult to accurately measure CFM at the inlet.

I can play with these numbers and get drastically different results which isn't boasting well for the software providing a "max-temp."

It does however, tell me where the hot spots are and which configurations are relatively better which is a strong plus.

If anyone's figured out how to utilize the software further I would be glad to hear about it.

- Bram

 

[Tmoose]

RE: variations in contact resistance (thermal and electrical)

I guess I'm not surprised since computer processors are (and must be) mounted with fancy thermal grease, and Cadillacs' and other GM cars' accessories were plagued with connector issues a decade or so back.