Volumentransport

Volumentransport, or volumetric transport, refers to the movement of fluid volume through a medium or across a boundary. It is quantified by the volumetric flow rate Q, defined as the volume of fluid passing a given surface per unit time. The standard units are cubic meters per second (m^3/s) or liters per second (L/s). In many contexts, volumentransport is analyzed independently of fluid density; the corresponding mass flow rate is ṁ = ρ Q, where ρ is the fluid density.

The fundamental relation Q = v A expresses that volume transport depends on flow speed v and cross-sectional area A. The continuity equation requires that, in the absence of sources or sinks, Q remains constant along a streamline. Advection is the primary mechanism for volumentransport, though diffusion and dispersion influence composition and distribution within the moving fluid. For porous media, Darcy's law provides a relation between pressure drop and volumetric flow rate: Q = −κ A ΔP / μ L, with κ the permeability and μ the dynamic viscosity.

Applications span engineering and biology: design and operation of pipelines, water supply and wastewater networks, HVAC systems, chemical processing, and lab-on-a-chip microfluidics. In physiology, volume transport describes interstitial and capillary fluid movement essential to tissue hydration and nutrient delivery. Measurement methods include flow meters, rotameters, and ultrasonic or electromagnetic sensors.

See also: volumetric flow rate, mass flow rate, continuity equation, Darcy's law, Navier–Stokes equations.