PerspectiveApplied Physics

Closing In on Models of Wall Turbulence

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Science  09 Jul 2010:
Vol. 329, Issue 5988, pp. 155-156
DOI: 10.1126/science.1192013

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Turbulence created when fluids flow past surfaces, called wall turbulence, affects the flux of water vapor and CO2 from the ocean's surface, causes drag on airplanes and ships, and influences how atmospheric pollutants are transported near Earth's surface. Wall turbulence presents a particularly difficult computational problem, because very small motions that occur in a thin inner layer near the wall must be modeled accurately (see the figure). This inner layer is critical because it contains the region where the effects of molecular transport mechanisms, such as viscosity, resist the transport of momentum, heat, and/or mass between the wall and the fluid. These motions cannot be described in sufficient detail with direct computation; the number of grid points within the layer where numerical calculations would need to be performed would lead to an impractically large task.