Turning up the heat in turbulent thermal convection
| Autor: | Charles R. Doering |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Convection
Physics Multidisciplinary Buoyancy Convective heat transfer Turbulence Mechanics engineering.material 01 natural sciences Physics::Geophysics 010305 fluids & plasmas Physics::Fluid Dynamics Commentaries 0103 physical sciences Thermal Heat transfer Fluid dynamics engineering Astrophysics::Solar and Stellar Astrophysics 010306 general physics Physics::Atmospheric and Oceanic Physics Dynamo |
| Zdroj: | Proc Natl Acad Sci U S A |
| Popis: | Convection is buoyancy-driven flow resulting from unstable density stratification in the presence of a gravitational field. Beyond convection’s central role in myriad engineering heat transfer applications, it underlies many of nature’s dynamical designs on larger-than-human scales. For example, solar heating of Earth’s surface generates buoyancy forces that cause the winds to blow, which in turn drive the oceans’ flow. Convection in Earth’s mantle on geological timescales makes the continents drift, and thermal and compositional density differences induce buoyancy forces that drive a dynamo in Earth’s liquid metal core—the dynamo that generates the magnetic field protecting us from solar wind that would otherwise extinguish life as we know it on the surface. The structure of the Sun itself relies on convection in the outer layers to transfer heat from the interior to radiate away from the surface. The key feature of convection is transport: Thermal convection actively transports the heat that generates the density variations that produce the buoyancy forces, and determining the rate at which “heat rises” in turbulent convection is one of the most important open problems in fluid dynamics. In PNAS, Iyer et al. (1) report the results of large-scale computational simulations revealing heat transfer rates in accord with one of two competing theories for turbulent convection in the strongly nonlinear regime. The problem that Iyer et al. address is one of longstanding interest and tremendous influence. Inspired by Henri Benard’s (2) turn of the 2 0 t h century experiments, Lord Rayleigh (3) introduced a minimal mathematical model for buoyancy-driven thermal convection in 1916. His model for what has come to be known as “Rayleigh–Benard convection” consists of a layer of fluid between impermeable horizontal boundaries separated vertically by distance H and held at fixed temperatures differing by Δ T , the higher temperature being on the … [↵][1]1Email: doering{at}umich.edu. [1]: #xref-corresp-1-1 |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|