Large eddy simulations of a turbulent channel flow with a deforming wall undergoing high steepness traveling waves Academic Article uri icon

abstract

  • Backward traveling waves over a wall of a fully developed turbulent channel are known to reduce the drag coefficient, flow separation, and turbulence intensity. Based on previous studies of traveling waves with a small steepness (s = a/ > 0.0625, a: nondimensional amplitude, : nondimensional wavelength), it is thought that the nondimensional wave-speed (C = C*/U*, C*: dimensional wave-speed, U*: mean channel velocity) is required to be more than one to have a zero net drag and a high reduction in the turbulent kinetic energy (TKE). This idea is tested here for waves with higher wave steepness (0.05 > s > 0.15) at various wave-speeds using large eddy simulations of a fully developed turbulent channel in which one wall is undergoing a traveling wave. It is found that the increase in wave steepness decreases the wave-speed at which a net zero drag is obtained, e.g., for waves with steepness of s = 0.05, 0.075, and 0.15, the wave-speed is, approximately, C = 1.6 0.1, 0.9 0.1, and 0.7 0.1, respectively. Similarly, the increase in wave steepness decreases the wave-speed at which TKE of the flow in the vicinity of the wave is highly reduced, e.g., qualitatively minimized. In fact, the wave-speeds at which the high reduction in TKE is observed in this study are C = 1.2, 1.2, and 0.6 for waves with wave steepness of 0.05, 0.075, and 0.15, respectively.

published proceedings

  • PHYSICS OF FLUIDS

author list (cited authors)

  • Akbarzadeh, A. M., & Borazjani, I.

citation count

  • 18

complete list of authors

  • Akbarzadeh, Amir M||Borazjani, Iman

publication date

  • December 2019