Current
A current is a directed flow of fluid through a region. It transports fluid and can carry heat, momentum, and dissolved or suspended material.
Pressure gradient: A spatial change in pressure that exerts force on a fluid. Pressure differences can initiate and accelerate fluid flow.
Fluid: A substance that deforms continuously under applied shear stress, including liquids and gases. Currents are flows of fluids rather than rigid bodies.
Ocean current: A persistent, directed movement of seawater driven by wind, density differences, tides, or other forces. Ocean currents transport heat, nutrients, and water across basins.
Diffusion: The net movement of particles from regions of higher concentration toward lower concentration through random motion. Diffusion transports matter without requiring a directed bulk current.
Continuity equation: An equation expressing conservation of mass in a flowing medium. It relates current speed and cross-sectional area when fluid mass is conserved.
Velocity field: A function assigning a velocity vector to each position in space and time. It represents the direction and speed of a current throughout a region.
Atmospheric circulation: Large-scale movement of air that redistributes heat and moisture around Earth. Air currents form part of the circulation patterns that shape climate and weather.
Convection: Heat transfer through the bulk movement of a fluid, often alongside conduction. A current can carry heat as part of convection, though the terms are not identical.
Navier–Stokes equations: A set of equations describing how forces, pressure, and viscosity govern fluid motion. These equations provide a general mathematical framework for predicting currents.
Volumetric flow rate: The volume of fluid passing through a surface per unit time. It quantifies how much fluid a current carries through a cross-section.