Large Eddy Simulation of Turbulent Flow in Channels with Wavy Walls Including Both Compliant Walls and Walls with Prescribed Motion.
NIELSEN ENGINEERING AND RESEARCH INC MOUNTAIN VIEW CA
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The effects of prescribed wall motion on turbulent channel flow were examined with the objective of understanding the drag mechanisms and obtaining a possible means for drag reduction. A computer program for large-eddy simulation LES of turbulent flow in a channel was modified to treat the case of time-varying wall motion using linearized boundary conditions. The code was applied to flow in a channel with prescribed wall motion on one wall. It was found that the results can be qualitatively explained by a model based on a Stokes-like layer near the moving wall. This provides a theory which can be used to guide the selection of parameters. Considering both viscous and pressure drag components, it was found that drag reduction is possible under certain conditions of wall motion. However, work is required to drive the wall motion to produce this effect and the effort expanded can be a considerable fraction of the reduced through-flow energy requirements. The major effects of the wall motion are restricted to the viscous sublayer of the turbulent flow.
- Fluid Mechanics