I cannot get velocity field profile of fluid when adding heats (Non-isothermal flow)

Hi!

I'm simulating non-isothermal simulation and my problem is I cannot get the velocity profile.
I can see the temperature is changing due to heat source from underneath but I do not know why the velocity decreases and does not follow what I expected. ( I attached file)

I looked up water cooling model and I followed most of them but it does not work.

Anybody help me?
I attached my file.

Best
Youngjoon