TY - JOUR

T1 - Periodically driven Taylor-Couette turbulence

AU - Verschoof, Ruben A.

AU - te Nijenhuis, Arne K.

AU - Huisman, Sander G.

AU - Sun, Chao

AU - Lohse, Detlef

N1 - Cambridge UP deal

PY - 2018/5/10

Y1 - 2018/5/10

N2 - We study periodically driven Taylor-Couette turbulence, i.e. the flow confined between two concentric, independently rotating cylinders. Here, the inner cylinder is driven sinusoidally while the outer cylinder is kept at rest (time-averaged Reynolds number is Rei = 5 × 105). Using particle image velocimetry, we measure the velocity over a wide range of modulation periods, corresponding to a change in Womersley number in the range 15 ≤ Wo ≤ 114. To understand how the flow responds to a given modulation, we calculate the phase delay and amplitude response of the azimuthal velocity. In agreement with earlier theoretical and numerical work, we find that for large modulation periods the system follows the given modulation of the driving, i.e. the behaviour of the system is quasi-stationary. For smaller modulation periods, the flow cannot follow the modulation, and the flow velocity responds with a phase delay and a smaller amplitude response to the given modulation. If we compare our results with numerical and theoretical results for the laminar case, we find that the scalings of the phase delay and the amplitude response are similar. However, the local response in the bulk of the flow is independent of the distance to the modulated boundary. Apparently, the turbulent mixing is strong enough to prevent the flow from having radius-dependent responses to the given modulation.

AB - We study periodically driven Taylor-Couette turbulence, i.e. the flow confined between two concentric, independently rotating cylinders. Here, the inner cylinder is driven sinusoidally while the outer cylinder is kept at rest (time-averaged Reynolds number is Rei = 5 × 105). Using particle image velocimetry, we measure the velocity over a wide range of modulation periods, corresponding to a change in Womersley number in the range 15 ≤ Wo ≤ 114. To understand how the flow responds to a given modulation, we calculate the phase delay and amplitude response of the azimuthal velocity. In agreement with earlier theoretical and numerical work, we find that for large modulation periods the system follows the given modulation of the driving, i.e. the behaviour of the system is quasi-stationary. For smaller modulation periods, the flow cannot follow the modulation, and the flow velocity responds with a phase delay and a smaller amplitude response to the given modulation. If we compare our results with numerical and theoretical results for the laminar case, we find that the scalings of the phase delay and the amplitude response are similar. However, the local response in the bulk of the flow is independent of the distance to the modulated boundary. Apparently, the turbulent mixing is strong enough to prevent the flow from having radius-dependent responses to the given modulation.

KW - UT-Hybrid-D

KW - Taylor-Couette flow

KW - Turbulent flows

KW - Rotating turbulence

UR - http://www.scopus.com/inward/record.url?scp=85047125052&partnerID=8YFLogxK

U2 - 10.1017/jfm.2018.276

DO - 10.1017/jfm.2018.276

M3 - Article

AN - SCOPUS:85047125052

VL - 846

SP - 834

EP - 845

JO - Journal of fluid mechanics

JF - Journal of fluid mechanics

SN - 0022-1120

ER -