Flow = driving force ÷ resistance

$\text{flow} = \frac{\text{driving force}}{\text{resistance}}$

Formula	Flow	Driving force	Resistance	Topic
$I = \frac{V}{R}$	Current $I$	Voltage $V$	$R$	HVDC cable
$\dot Q = \frac{\Delta T}{R_{th}}$	Heat $\dot Q$	$\Delta T$	$R_{th}$	Buildings, district heating pipe
$\dot V = \frac{kA}{\mu}\frac{\Delta p}{L}$ (Darcy, not on sheet)	Water $\dot V$ (rock)	$\Delta p$	$\frac{\mu L}{kA}$	Geothermal doublet

Resistances in series → add ($R_{ins} + R_{soil}$, wall layers).

Power = flow × driving force

• Electric: $P = I\,V$
• Pumping: $P = F\cdot v = (\Delta p A)\cdot\frac{\dot V}{A} = \dot V\,\Delta p$ → geothermal COP = $\dot Q_{geo} / (P/\eta_{pump})$