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Leipzig Neutral

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Scope

The benchmark is open to participants of the Wakebench project using atmospheric boundary layer models. This is the first element of the building-block approach in this range, so it should be mandatory if you intend to participate with this model in other test cases down the line.

Objectives

Demonstrate how ABL models reproduce the characteristic Ekman spiral in neutral conditions represented by prescribed Leipzig profile conditions.

Data Accessibility

The benchmark is offered to participants of the IEA Task 31 Wakebench. In the future it will be open for public access.

Input data

The conditions for simulating the Leipzig wind profile in neutral conditions are:

  • Geostrophic wind: Ug = 17.5 m/s, Vg=0
  • Coriolis parameter: fc = 1.13e-4 s-1
  • Roughness length: z0 = 0.3 m
  • Obukhov length: L = ∞
  • Use dry air with a density ρ = 1.225 kg/m3 and dynamic viscosity μ = 1.73e-5 kg/ms

Validation data

The validation data consists on vertical profiles of velocity components and eddy viscosity as estimated by Lettau (1950).

Model runs

A 3 km high domain should be used, sufficient to fit the boundary layer height with some margin.

Output data

Please provide vertical profiles of velocity components (U,V), turbulent kinetic energy (tke) and turbulent viscosity (nu_t) using the file naming and format convention described in the Windbench user's guide with profID = outlet. Hence, the output profile file contains the following variables (header), in this order: Z(m), U(m/s), V(m/s), tke(m2/s2), nu_t(m2/s).

Remarks

This benchmark is based on prescribed boundary conditions in order to evaluate the scatter of different ABL models. A follow-up benchmark, Leipzig_Stratified, will allow the participant to obtain the best fit to the Leipzig data with unconstrained boundary conditions and by introducing stability.