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 -