The Effect of Finite Compliant Panels on the Development of Linear Disturbances in the Rotating-Disk Boundary Layer #

Sara Ahmad Almammary, Zahir Hussain, Christian Thomas.

14:10 Monday in 4Q08.

Part of the Boundary layer flows and stability session.

Abstract #

The rotating disk boundary layer is a classic model for the study of cross-flow instability due to its similarity to flow on a swept wing, and is a helpful simplification of a variety of flows in industrial applications with rotating setups. The study of the transition from laminar to turbulent flow in the boundary layer region has sparked a lot of interest due to its applicability to drag reduction, allowing for reduced energy consumption. Controlling transition can be achieved by active or passive flow control methods. Compliant panels are one type of passive method that can be employed to postpone laminar-turbulent transition. We consider a model in which an annular region of the disk surface is replaced by a compliant panel. The purpose of this research is to examine whether a compliant panel of finite length may be used as a passive drag reduction technique for controlling convective and absolute instabilities over a rotating disk. If so, what is the appropriate length and position of the compliant panel? To address this problem, a velocity–vorticity form of the linearised Navier–Stokes equations (Davies & Carpenter (2001)) is used to study the behaviour of convective and absolute instabilities that develop in the rotating disk boundary layer. The compliant wall is modelled using a plate–spring model. Time-periodic and impulsive forcing are used to excite linear disturbances located at a fixed radius.

Davies, C. & Carpenter, P. W. 2001 A novel velocity-vorticity formulation of the Navier–Stokes equations with applications to boundary-layer disturbance evolution. J. Comput. Phys. 172, 119–165 C. Thomas and C. Davies, On the impulse response and global instability development of the infinite rotating-disc boundary layer, J. Fluid Mech. 857, 239 (2018).