reológiáját

Rheology is the branch of physics that studies the flow and deformation of matter, encompassing both fluids and soft solids. It examines how materials respond to external stresses or strains, characterising their viscosity, elasticity, and plasticity. Traditional fluid mechanics often assumes Newtonian behaviour, where shear stress is proportional to shear rate. Rheology expands this by exploring non‑Newtonian fluids—substances whose viscosity changes with shear rate, such as shear‑thinning syrups or shear‑thickening suspensions—and viscoelastic solids that exhibit both viscous flow and elastic recoil.

The fundamental equation in rheology relates shear stress (τ) to shear rate (γ̇) through the constitutive law, typically τ = η(γ̇)γ̇ for shear‑dependent fluids or more complex models like the Maxwell or Kelvin‑Voigt models for viscoelastic materials. Experimental techniques such as rotational rheometry, oscillatory shear tests, and creep–recovery measurements provide data to fit these models, capturing material behaviour under controlled conditions.

Rheology has broad applications across many fields. In materials science, it guides polymer processing and composite design. In geology, the flow of magma and glaciers is described rheologically. The food industry relies on rheology to optimise texture and stability. Biomedical science uses rheological measurements to characterize tissues, gels, and blood, aiding diagnostics and drug delivery design.

Because many natural and industrial systems display complex flow behaviour, rheology bridges fundamental physics and engineering, supplying the quantitative tools needed to predict and control material response in real‑world applications.