Hydrodynamikkens

Hydrodynamikkens is the Danish term for hydrodynamics, the branch of fluid dynamics that studies the motion of liquids and the forces acting on them. It encompasses theoretical descriptions, experimental methods, and engineering applications, distinguishing itself from hydrostatics, which deals with fluids at rest.

The motion of fluids is governed by conservation laws. For a Newtonian fluid, the fundamental equations are the continuity equation for mass conservation and the momentum equation, commonly expressed as the Navier–Stokes equations in their general form. In special cases, the Euler equations describe inviscid flow, and Bernoulli’s principle applies along a streamline. Fluid flows may be incompressible or compressible, laminar or turbulent, and Newtonian or non-Newtonian. Practical analysis often employs boundary layer theory to describe thin viscous regions near solid boundaries and various turbulence models, such as Reynolds-averaged Navier–Stokes (RANS) or large-eddy simulation (LES), for complex flows.

Methods used in hydrodynamics include analytical solutions for idealized problems, controlled laboratory experiments, and numerical simulations. Computational fluid dynamics (CFD) enables detailed studies of realistic geometries and operating conditions, often requiring turbulence modeling and high-performance computing.

Applications span many sectors, including aerodynamics of aircraft, naval and marine engineering, hydraulics of pipelines and dams, weather and ocean modeling, and biomedical flows in the cardiovascular system. The field draws on advances in mathematics, physics, and computer science to predict, optimize, and understand fluid motion in natural and engineered systems.

Historically, ideas trace back to principles from Archimedes and Bernoulli, with formal formulations by Euler, d’Alembert, Navier, and Stokes. The 20th century saw the rise of computational methods that expanded the scope of hydrodynamics across disciplines.