This command is used to apply a thermal body load (power per unit volume).

$f_2$ is an optional CURVE or FUNCTION describing the exact total power of the heat source. It is needed in situations where the heat source described by $f_1$ (power/unit volume) is partially outside the body where the energy is to be deposited. The magnitude of $f_1$ is then scaled with a factor $\alpha$ in order to match the specified total power in $f_2$.

$\displaystyle{ \alpha \int_V f_1(\mathbf{x}, t) \mathrm{d}V = f_2(t)}$

$V$ is the body volume, $\mathbf{x}$ is a spatial coordinate and $t$ is the time. Hence, the heat power per unit volume $p$ deposited at a location $\mathbf{x}$ becomes:

$p = \alpha \cdot f_1(\mathbf{x}, t)$