PressureFlow

Pressureflow is the relationship between the pressure difference across a section of a fluid system and the resulting flow rate of the fluid. It is a central concept in fluid dynamics, describing how pressure gradients drive motion through pipes, channels, or porous media. In many contexts, the relationship is modeled by a hydraulic resistance, so that ΔP = R_h Q, where ΔP is the pressure drop, Q is volumetric flow rate, and R_h summarizes geometry and fluid viscosity.

For laminar flow in a circular tube, Poiseuille's law provides a concrete form of this relationship: ΔP = (8 μ L Q)/(π r^4). Equivalently, Q = (π r^4 ΔP)/(8 μ L). In other regimes—turbulent flow, non-Newtonian fluids, or compressible effects—the exact dependence deviates, but the general principle remains: higher pressure differences drive higher flow, subject to energy losses and flow resistance.

In biological systems, the pressureflow concept helps explain cardiovascular perfusion: flow equals pressure difference divided by vascular resistance (F = ΔP / R). The body can regulate perfusion by altering pump pressure and vascular tone, thereby changing the effective resistance to maintain tissue blood flow.

In engineering, pressureflow underpins the design and analysis of pumps, valves, piping networks, and HVAC systems. System curves show how flow varies with pressure and are used to select components and predict performance. In microfluidics and related fields, pressureflow relationships enable precise control of fluid movement at small scales.

Measurement of pressureflow utilizes pressure sensors and flow meters to construct Q versus ΔP curves. Limitations include non-Newtonian fluids, transient or pulsatile conditions, turbulence, and compressibility. See also Ohm's law for fluids, Poiseuille's law, Bernoulli's equation, and head loss concepts.