Atmospheric Boundary Layer#
1. Project Description#
The objective of this project is to reproduce the properties of atmospheric boundary layer (ABL) [1] from CFD-LES simulations. The resolution levels “lvl3” and “lvl4” of the digital wind tunnel are designed for high-rise and low-rise buildings, respectively. The building reference heights for each level are arbitrated at H lvl3 = 150 m and H lvl4 = 15 m. One convective time scale is defined as \(CTS = H / U_H\).
Source of target results:
List of analysed cases |
|||||
|---|---|---|---|---|---|
Roughness Category (according to EN 1991-1-4) |
CAT 0 |
CAT I |
CAT II |
CAT III |
CAT IV |
\(z_0\) [m] (roughness height) |
0.003 |
0.01 |
0.05 |
0.3 |
1.0 |
\(d / z_0\) (fin height to \(z_0\) ratio) |
0 |
100 |
40 |
17 |
7 |
Ilustration of computational domain, synthetic eddy inlet and uniformly distributed fins with height \(d\) at the floor.#
2. Simulation Setup#
Ilustration of the computational grid, levels 3 and 4 are probed for high and low-rise building, respectively.#
Simulation parameters (same for all cases) |
||
|---|---|---|
lvl3 |
lvl4 |
|
\(H\) [m] (arbitrated height) |
150 |
15 |
\(\Delta x / H\) (spatial res.) |
1.33E-2 |
6.67E-2 |
\(\Delta t / CTS\) (temporal res.) |
8.00E-4 |
2.67E-3 |
\(T / CTS\) (statistical sample size) |
2.56E+2 |
1.71E+3 |
\(Re_H = U_H H / \nu\) |
4.89E+5 |
3.26E+4 |
Computational performance (NVIDIA RTX A5500) |
|||||
|---|---|---|---|---|---|
Case |
CAT 0 |
CAT I |
CAT II |
CAT III |
CAT IV |
Node count (million) |
69 |
69 |
69 |
69 |
69 |
Allocated memory (Gb) |
10 |
10 |
10 |
10 |
11 |
Elapsed time (h) |
6 |
6 |
6 |
7 |
7 |
3. Results: Velocity and Turbulence Profiles#
Average Velocity#
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Turbulence Intensity#
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4. Results: Two-Point Statistics#
Integral Lenght Scale#
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5. Results: Energy Spectra#
Longitunal Velocity Spectrum#
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Normal Velocity Spectrum#
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Changelog#
Execution Notes
18 April 2024
Uploaded point comparisons, simulations executed with Nassu release v1.5.4.