If a fluid flows through conduits, the pressure decreases in the direction of flow (this is the result of fluid friction which results in the production of heat).

The concrete current – pressure difference relation (IV(∆pR)) is called the resistive characteristic or flow characteristic. The associated pressure difference along a path is called the resistive pressure difference.

Left: Resistive characteristic for laminar flow; right: for turbulent flow. A value of a combination of characteristic values of the flow—called the Reynolds number—tells us if a flow is laminar or turbulent.

The relation can be expressed graphically (flow versus resistive pressure difference), formally with an equation interpolating the measured function IV(∆pR), or with the help of the resistance R_V in the case of laminar flow.

hydraulic resistance, conductance, laminar flow, turbulent flow, resistive pressure difference, laminar flow law, turbulent flow law,

hydraulische Widerstands-Charakteristik (Strömungscharakteristik)