Heat flux is the rate of heat transfer per unit area. It represents the amount of heat energy transferred through a surface per unit time. Mathematically, it is expressed as the amount of heat transferred per unit time and per unit area,
Where:
- = heat flux (in watts per square meter, W/m²)
- = amount of heat transferred (in joules, J)
- = time interval (in seconds, s) over which the heat transfer occurs.