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Title: Spatial evolution of wakes generated by side by side cylinders
Author: Graca Avelar Camarinha, Marilia
ISNI:       0000 0004 8499 6553
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2019
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In this thesis, exploration of one and two-point statistics on side by side square cylinders with variable spacing between them together with assessment of the nature of dissipation in this type of flow and inspection of the validity of the classical scaling of the dissipation rate was performed. The research focuses on the spatial evolution of dual wakes behind a pair of square cylinders at a Reynolds number -- $Re_H = 6.4\times 10^3$, based on the dimensions of a single square cylinder at a free-stream velocity $U_{\infty} = 0.2$ ms$^{-1}$. Two-dimensional particle image velocimetry (PIV) measurements in a water tunnel were performed at different measurement stations for the three different spacing between the centre of the side by side square cylinders - denoted by $g$ - in order to assess the baseline characteristics for this type of flow, integral length scales based on spatial correlations of the fluctuating velocity components and estimation of the dissipation and subsequent relationship between the constant of the dissipation rate $C_{\epsilon}$ and the Reynolds number based on the Taylor microscale $Re_{\lambda}$. It was found that long range correlations based on the streamwise fluctuating component exist for the configurations with smaller spacing between the cylinders tested. For the current work, it was found that the most suitable integral length scale to assess the behaviour of $C_{\epsilon}-Re_{\lambda}$ is the longitudinal integral length scale based on the transverse fluctuating velocity component $v^{\prime}$. In literature, it has been seen that the relationship between $Ce_{\epsilon}$ and $Re_{\lambda}$ follows a power law: $C_{\epsilon} \sim Re_{\lambda}^{-n}$; a $n \simeq 2$ power law relationship was found between $C_{\epsilon}-Re_{\lambda}$ across all $g$ configurations tests after $X/g \geq 1$.
Supervisor: Vassillicos, John Christos ; Buxton, Oliver Sponsor: FP7 Marie Curie Multisolve project
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral