hydrodymische

Hydrodynamics is the branch of fluid dynamics that describes the motion of fluids, especially liquids, and the forces acting on them. It covers steady and unsteady flows, compressible and incompressible fluids, and phenomena ranging from pipe flows to complex free-surface and jet flows. The field combines experimental observations with mathematical models to predict how fluids respond to pressure, gravity, and boundary conditions.

The motion of a viscous, Newtonian fluid is governed by the conservation of mass and momentum. For a viscous fluid, the Navier–Stokes equations express momentum balance; for ideal (inviscid) fluids, the Euler equations apply. Incompressible flows satisfy the continuity equation ∇·u = 0; compressible flows involve density variations and the energy equation.

In many practical cases, simplified concepts help intuition. Bernoulli’s principle relates pressure and velocity along a streamline in steady, inviscid, incompressible flow. Potential flow theory pursues solutions with zero vorticity. The Reynolds number Re = ρUL/μ characterizes the transition between laminar and turbulent flow and helps select modeling approaches.

Analytical solutions exist for simple geometries; most realistic problems require numerical methods, notably computational fluid dynamics (CFD), and experimental techniques such as flow visualization and particle image velocimetry (PIV).

Applications include ship and aircraft design, hydraulics and piping systems, blood flow in physiology, environmental and geophysical flows, and industrial mixing processes. Ongoing research addresses turbulence, multiphase flows, and fluid-structure interaction.