hydrodynamiku

Hydrodynamics is the branch of physics that studies the motion of fluids and the forces acting on them. It treats liquids as continuous media and applies conservation laws for mass, momentum, and energy to describe how fluids respond to pressures, gravity, and boundaries.

The core equations are the continuity equation and the momentum equations. The Navier-Stokes equations describe viscous flows, while the Euler equations apply to inviscid (non-viscous) fluids. Constitutive relations link stress to deformation, enabling the description of different fluid types. For incompressible flows, density is treated as constant, which simplifies the equations; compressible flows allow density changes and are central to gas dynamics and high-speed phenomena.

Key concepts include the distinction between laminar and turbulent flows, often characterized by the Reynolds number, which compares inertial and viscous forces. Potential flow treats fluids as irrotational and inviscid, yielding simplified solutions, while boundary layer theory accounts for viscous effects near solid surfaces. Other specialized models include the shallow water equations for long-wavelength waves and various turbulence models used in practical simulations.

Applications span ship and submarine design, aerodynamics of fluid machinery, hydraulic engineering, oceanography, meteorology, and biological flows in physiology. Hydrodynamics informs the planning of propulsion systems, wave and coastal modeling, and the analysis of blood flow and other biological fluids.

Researchers use experimental methods such as flow visualization and wind or water tunnels, alongside computational approaches. Computational fluid dynamics employs finite-volume or finite-element methods, as well as lattice Boltzmann simulations, to solve the governing equations across a wide range of scales and conditions.