I am using Creo8.0 trying to run a thermal simulation on a simple block with a convection condition applied to the bottom. For the full simulation, I am planning on starting at 20C (also initial temp as defined in transient analysis), ramping up to 90C, then down to -35C. I keep noticing an initial dip in the temperature at the measure point at the bottom of the block for the first few minutes, which should not be there as I am trying to increase the temp from 20C to 90C, so it should not be getting colder at all during that ramp. I was originally using 90C as the bulk temperature in the convection condition, with the table ramping up from .22 (20C) to 1 (90C). I decided to run some tests where I hold at 20C using various bulk temperatures and table value combinations to better understand the table function tool, but I am still lost. Using a bulk temp of 90C and 6 table rows with values of 0.22, I am still seeing the temperature dip significantly (Test1). Using a bulk temp of 1C and table rows with values of 20, I am seeing an increase in temperature (Test2). Using a bulk temp of 20C and table rows with values of 1, I am seeing a steady 20C, which I am looking for (Test3). However, when I use this 20C bulk temp and adjust the table values for the full simulation to hit my max (90C, using 4.5 as table value) and min (-35C, using -1.75 as table value) temperatures, I am seeing the temperature go well above and below the temperatures I input (seeing 130C on graph, tried to input 90C (20C x 4.5)). I tried another simple check, where I tried to hold at 20C for a few minutes, before increasing to 40C (Test4). This pushed the measured temperature on the bottom of the block to settle at around 57.77 C. In summary, the bulk temperature is not working how I anticipated, and does not seem to be as simple as multiplying the table value times the bulk temperature for a given time. The temperatures seem to be compounding on top of each other somehow, as I keep getting measure results hotter than the input temperatures, which does not make sense to me. Any more details on how this convection condition time variant bulk temperature works would be appreciated, or if anyone has suggestions for how I can accurately simulate my hot and cold temperatures while avoiding the initial drop in temp I am seeing, I could use some advice. Thanks in advance!
