Mean Turbulence Statistics from Direct Numerical Simulations of Stably Stratified Channel Flows with One- and Two-Dimensional Surface Temperature Heterogeneity

<p>The dataset contains a suite of Direct Numerical Simulation (DNS) results of pressure driven stably stratified channel flows, both with homogeneous and heterogeneous surface temperatures. The one-dimensional temperature heterogeneity is organized in streamwise infinite strips of width λ<sub>y</sub>/2 with spanwise varying surface temperature with difference Δ θ, while the same temperature difference is maintained between the lower and upper wall to enforce overall stable stratification. In the cases with two-dimensional surface heterogeneity, the strips have a finite streamwise length λ<sub>x</sub>/2.
Two different Reynolds numbers, i.e. Re<sub>τ</sub>=180 and Re<sub>τ</sub>=550, and two different Richardson numbers Ri<sub>τ</sub>=120 and Ri<sub>τ</sub>=960 are considered for the heterogeneous cases. For reference, a number of canonical stable channel flow cases with homogeneous surfaces at different Reynolds and Richardson numbers is also included. The simulations were run until a statistically steady state was reached, after which turbulence statistics were collected over a certain time window (30 h/u<sub>τ</sub> in most cases, see 'T_av' column in StableChannel_Overview.csv. ).
The dataset is generated with the SP-Wind code, an in-house DNS/LES code developed at KU Leuven. For details of the code structure and simulation set-up we refer to Bon and Meyers (2022) and Bon et al. (2023). We note that both publications also contain a schematic illustration of the surface heterogeneity configurations (Figure 1 there). </p>
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The dataset is organized as follows. A total of 46 simulations is included, and each has a separate folder. Each folder contains global simulation properties in flowproperties.csv, and horizontally-averaged profiles of relevant variables in profiles_cc.csv (variables on cell-centered grid) and profiles_st.csv (vertical derivatives on staggered grid). Besides, the folders of the streamwise homogeneous cases (k<sub>x</sub> = 0) contain streamwise-averaged yz-planes of velocity components, potential temperature, Reynolds stresses and temperature fluxes. For the cases with two-dimensional heterogeneity (k<sub>x</sub> > 0), phase-averaged 3D fields of these variables are included. Note that all variables are time-averaged. An overview of the mean flow properties of each simulation is provided in the file StableChannel_Overview.csv, which also includes relevant input parameters such as domain size and grid resolution.
Fore more information, we refer to the readme.txt file located in the dataset and to the two related publications.

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Acknowledgements
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The authors acknowledge support from the Research Foundation Flanders (FWO, Grant Number G098320N). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation – Flanders (FWO) and the Flemish Government.
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References
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Bon, T. & Meyers, J. (2022), Stable channel flow with spanwise heterogeneous surface temperature. Journal of Fluid Mechanics (2022), vol. 933, A54, doi:10.1017/jfm.2021.1113
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Bon, T., Broos, D., Cal, R. B., & Meyers, J. (2023), Secondary flows induced by two-dimensional surface temperature heterogeneity in stably stratified channel flow. Journal of Fluid Mechanics, vol. 970, A20, doi:10.1017/jfm.2023.619
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