I ran a case with low inlet velocity (200FPM) and no heat sink. TASPCB ran successfully and produced good results. However, when I added a heat sink on an IC, the air and junction temperature become unrealistically large. What could be the problem?
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Most of the time this is a convergence problem. Always check results for consistency and accuracy. (1) If the solution variables, velocity and pressure, are not reasonable, change the solution time step by clicking Settings>Properties to get Property Sheet window, click Solution tab, in Air Flow Time Integration section, decrease CFL and Max step size by a reasonable amount to get reasonable velocity and pressure distribution first. (2) If the velocity and pressure are OK. Skip step 1. In the Air Thermal Time Integration section, try to decrease Step Size and increase the Max number of steps. (3) In the Air/Board Thermal Balance section, increase Max iterations and adjust the Board iter cutoff. |
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