Problem with HGEN load on transient thermal analysis
 

Hello,

I have been working on transient thermal analysis with ANSYS but I had a weird problem with the temperature not rising enough. I went back and made a very basic model to test if the BFA function works properly and found it doesn't. (See the attached code.)

I'm using a body force load on area to heat the volume with HGEN function. I'm using unconstrained model just to see how much transient heat pulse increases the temperature.

When calculating the temperature increase in the volume on paper and comparing it to the simulation results, I found that the ANSYS result is exactly 20 % of what it should be. The ratio changes between 20 and 50 % depending on the dimensions I use for the volume.

All the scalar parameters on the ANSYS seem to be correct (dimensions, weight, volume and area of the volume as well as power density and time of the heat pulse). I believe I have somehow misunderstood the use of BFA,HGEN...-function which leads to too small energy input on the model.

The parameter value given for BFA,HGEN is in form of W/m2, is it not?

The model in attachment gives a temperature increase of 9.52 K even though the correct answer would be 47.6 K given the starting parameters.

Can someone help me out? Help would be much appreciated.

Best regards,
Juha