calculation of heat flux for constant temperature condition at different time
 

I am doing research on the combined effect of natural convection and forced convection by providing velocity through ventilation ports in a rectangular enclosure keeping bottom plate heated at constant temperature. I want to find heat flux on hot plate maintaining at constant temperature in order to find heat transfer coefficient at different time. Please let me know that how to get rid of it in ANSYS Fluent.

P.S- Wall heat flux value through CFD-Post in ANSYS Fluent is giving much higher value.