A pressure difference is the difference of pressures at two points in a fluid.

Pressure differences are driving forces for different processes: by itself, a fluid flows from points where the pressure is high to points where it is lower.

delta_p

Pressure differences along a closed hydraulic circuit (loop rule):

     delta_p1 + delta_p2 + … = 0

Steady resistive flow through a horizontal pipe:

     I_V = G_V*delta_p,     G_V = 1/R_V

G_V: hydraulic conductance, R_V: hydraulic resistance

Hydraulic power:

     P_hydr = delta_p*I_V

delta_p: pressure difference through which I_V flows

[delta_p] = Pa (Pascal), Pa = N/m^2, 1 bar = 10^5 Pa, 1 mmHg = 133 Pa

hydraulic driving force

pressure, hydraulic potential, resistive pressure difference, capacitive pressure difference, inductive pressure difference, pressure difference due to gravity

Since the pressure of a fluid is related to chemical, thermal, mechanical and other properties of materials, and to diverse processes, the pressure difference appears in many different relations.

Druckdifferenz, Druckunterschied