I'm having problems with a transient thermal study (2013 Simulation Professional) that plots bizarre temperature drops during early time steps (shorter times than equilibrium/steady state period). To diagnose, I've duplicated the problem with a simple cube part body, defining a circular face with a prescribed temperature load, two faces with convection, and an initial temperature load.

Screen capture and model files are attached.

Some details:

- Single body part model. Cube is 100mm each side. Circular split curve for temp load face is 50 mm dia.

- Temperature load within circular face is 240C.

- Convection inputs are 303K bulk ambient temp, 25 W/m^2 K coefficient. Top face (excluding temp circle) and bottom face selected.

- Initial temp is 30C using select all faces option.

- Four cube side faces are default boundaries (no heat exchange).

- Transient period is 1000s with 100s increments.

- Standard mesh 10mm.

A heat flux plot at these time frames also seems to support that something is wrong.

I came across a forum post with a similar problem and the suggested cause was choosing only external faces for initial temperature, leaving body to default of 0K temp. But I see no way to select entire part body for input to initial temperature. The dialogue permits only selection of faces. Not sure how SW handles initial temperature.