READ ME File For 'Effects of fetch length on turbulent boundary layer recovery past a step-change in surface roughness' Dataset DOI: 10.5258/SOTON/D3426 Date that the file was created: 04/2025 ------------------- GENERAL INFORMATION ------------------- ReadMe Author: Martina Formichetti, University of Southampton, 0000-0003-4450-334X Date of data collection: 07/2023 Information about geographic location of data collection: BLWT, Southampton University Related projects: The authors acknowledge funding from the Leverhulme Early Career Fellowship (Grant ref: ECF-2022-295), the European Office for Airforce Research and Development (Grant ref: FA 8655-23-1-7005) and EPSRC (Grant ref no: EP/W026090/1) -------------------------- SHARING/ACCESS INFORMATION -------------------------- Licenses/restrictions placed on the data, or limitations of reuse: Open access, License CC BY Recommended citation for the data: This dataset supports the publication: AUTHORS: M. Formichetti, D. D. Wangsawijaya, S. Symon, B. Ganapathisubramani TITLE: Effects of fetch length on turbulent boundary layer recovery past a step-change in surface roughness JOURNAL: Journal of Fluid Mechanics PAPER DOI: 10.1017/jfm.2025.311 -------------------- DATA & FILE OVERVIEW -------------------- This dataset contains: supplementaryMaterials.xlsl this file contains 11 spreadsheets named: - Constants, where all the constants used for the data analysis are defined - fig4a, this contains the friction coefficient vs Reynolds number data for all fetch lengths tested - plotted in figure 4a - fig4b, this contains the friction coefficient at fixed Reynolds number vs fetch length normalised by the boundary layer thicnkess of the case with the longest fetch length - plotted in figure 4b - fig5a, this contains the velocity deficit in inner units vs wall-normal distance normalised by boundary layer thickness for all fetch lengths tested plus smooth wall - plotted in figure 5a - fig5b, this contains the equivalent sandgrain roughness height calculated via the method in Monty2016 and an internal layer fitting method vs fetch length normalised by the boundary layer thicnkess of the case with the longest fetch length - plotted in figure 5b - fig6a, this contains the mean velocity profile stream-averaged across the drag balance in inner units vs wall-normal distance normalised by the equivalent sandgrain roughness height computed for the longest fetch case - plotted in figure 6a - fig6b, this contains the mean velocity profile stream-averaged across the drag balance in inner units vs wall-normal distance normalised by the equivalent sandgrain roughness height computed using the method from Monty2016 for each fetch length - plotted in figure 6b - fig6c, this contains the mean velocity profile stream-averaged across the drag balance in inner units vs wall-normal distance normalised by the equivalent sandgrain roughness height computed using the internal layer fitting method for each fetch length - plotted in figure 6c - fig7a, this contains the Reynolds stress component in inner units vs wall-normal distance normalised by boundary layer thickness for all fetch lengths tested - plotted in figure 7a - fig7b, this contains the Reynolds stress component in inner units vs wall-normal distance normalised by boundary layer thickness for all fetch lengths tested - plotted in figure 7b - fig7c, this contains the Reynolds stress component <-u'v'> in inner units vs wall-normal distance normalised by boundary layer thickness for all fetch lengths tested - plotted in figure 7c -------------------------- METHODOLOGICAL INFORMATION -------------------------- Description of methods used for collection/generation of data: floating element drag balance (M. Ferreira, P. Costa, B. Ganapathisubramani, "Wall shear stress measurement using a zero-displacement floating-element balance", 2024, Experiments in Fluids, vol. 65:4), planar particle image velocimetry with LaVision DaVis 10. Methods for processing the data: in-house processing code. Describe any quality-assurance procedures performed on the data: the floating element drag balance measurements were repeated three times to ensure the repeatability of the results. The measurement uncertainty of skin friction from the balance is estimated to be less than 1 %, the PIV data was sampled at 1Hz with a boundary layer turnover time of 267E3 to ensure statistical convergence of the mean fields. People involved with sample collection, processing, analysis and/or submission: M. Formichetti, D. D. Wangsawijaya -------------------------- DATA-SPECIFIC INFORMATION -------------------------- Number of variables: 14 Number of cases/rows: 12 (drag balance), 7 (PIV) Variable list, defining any abbreviations, units of measure, codes or symbols used: - nu, kinematic viscosity [m2/s] - utau, friction velocity [m/s] - Cf, local friction coefficient [-] - Rex, Reynolds number (Uinf*x/nu), where Uinf is the freestream velocity and x is the distance between the drag balance and the test section inlet [-] - L, fetch length [m] - delta2, boundary layer thickness measured above the drag balance for the longest fetch case [m] - delta99, boundary layer thickness measured above the drag balance for each fetch case [m] - Ud+, velocity deficit (Uinf-U)+ in inner units, where U is the streamwise mean stream-averaged velocity [-] - U+, streamwise mean stream-averaged velocity in inner units [-] - ks_2, equivalent sand-grain roughness height computed for the longest fetch case [m] - ks_IL, equivalent sand-grain roughness height computed with an internal layer fitting method [m] - ks_OLS, equivalent sand-grain roughness height computed with a method from Monty2016 based on outer layer similarity [m] - uu+, Reynolds stress component in inner units [-] - vv+, Reynolds stress component in inner units [-] - -uv+, Reynolds stress component <-u'v'> in inner units [-]