Turbulence modification in flow around a periodically deforming film

Abstract

A direct numerical simulation has been carried out for turbulent flow around a periodically deforming film. The film deformation is sinusoidal in the streamwise direction, whose nodes are fixed in space. The maximum amplitude of the deformation is limited within the linear sublayer. An unsteady generalized curvilinear coordinate and the collocated grid system are applied to the finite differencing of the NS equation. The computational results show that the turbulence intensities, the Reynolds shear stress and the wall-shear stress increase, in the case where the period of wall deformation is longer than the ratio of the wavelength of deformation to the fluid velocity in the buffer region. In contrast to this, these statistical quantities do not increase, in the case where the period of wall deformation is slightly shorter than the ratio. This difference is caused by the enhancement of mixing in the wall-normal direction and the modifications of the Q4 event due to the deformation.

Keywords:

• DNS
• Deforming wall
• Collocated grid system
• Turbulence modification
• Filmy structure of life