Diffuseflow

Diffuseflow is a term used to describe a mode of fluid transport in which flow and solute movement occur diffusely through a medium rather than through discrete, well-defined channels. The term is used across disciplines such as hydrogeology, soil science, and biomedical imaging to contrast diffuse or matrix-based transport with preferential flow through fractures, veins, or other concentrated pathways.

In porous media, diffuse flow results from the combined action of advection and molecular diffusion as fluids move under pressure gradients and interact with a tortuous pore network. It produces gradual spreading of solutes, with the rate governed by porosity, permeability, diffusion coefficients, and hydraulic conductivity. Mathematical descriptions commonly employ the advection-diffusion equation or related upscaled models that incorporate dispersion caused by heterogeneity.

In medicine and imaging, diffuse flow refers to the distribution of a tracer or contrast agent through tissue or organ parenchyma, not confined to major vessels. This affects signals in perfusion MRI, CT perfusion, or PET imaging and provides information about tissue viability, microcirculation, and edema. Measurement typically uses dynamic imaging combined with kinetic modeling and diffusion metrics such as apparent diffusion coefficient or perfusion parameters.

Terminology varies by field, and Diffuseflow can also appear as a brand or product name in commercial contexts. The concept remains an approach to understanding transport processes where diffusion and slow, widespread movement dominate over rapid, channelized flows.