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B02 - 2D Fields (Half-Blind)

Scope

The benchmark is a blind test starting in December 2017. A wind speed profile on the hill top is provided, in addition, a vertical (RHI) scan along the axis of 217° in the inflow to the hill top is given. Profiler data and additional met mast data as well as the vertical scan in the wake of the hill is withheld for validation

Data Accessibility

The benchmark is offered to participants of the NEWA (New European Wind Atlas) project and anyone else interested in participating.

Objectives

Evaluate flow across a forested hill. Evaluate turbulence models in a test site with well-defined boundary conditions. Evaluate the impact of model tuning.

Input data

The conditions for simulating the Kassel Forested Hill site are:

  • Digitized map of the Rödeser Berg hill with a 10m resolution.
  • Digitized map of the Forest height on top of the hill with 10m resolution.
  • Digitized Plant Area Density with a horizontal resolution of 10m and a vertical resolution of 1m.
  • Digitized Roughness map derived from CORINE data [100m resolution]
  • Wind Speeds/Directions: Measured at M200 (on the hill top) [30 min mean]
  • Obukhov Length: Measured at 60 m at the 200m mast (on the hill top) [30 min mean]
  • Coordinates of wind profilers/met masts along the transect line (217°)
  • Gravity g = 9.81 m/s2, Coriolis parameter f=1e-4 s-1
  • Use dry air with a density ρ = 1.225 kg/m3.
  • Image from an RHI lidar scan (vertical plane) along the transect line (217°) from the inflow up to the hill-top

Validation data

The validation dataset is composed of mean flow and turbulence data from cup and sonic anemometers, lidar profilers and lidar scanners. All data are averaged over 30 min.
The following data will be used for evaluation:

  • Wind Speed Profiles at the two met masts
  • Wind Speed Profiles from 3 Profilers along the Transect
  • 2D field from RHI lidar scans along transect line (217°) through the M200 mast.

The validation dataset includes mean and standard deviation statistics from the ensemble profiles

Model runs

The atmospheric conditions:

  • Run 1 (Neutral Stratification – 18.11.2016 22:20-22:50UTC):  WD (MM200 at 188m)=223.7°, WS (MM200 at 188m) = 16.9 m/s, WS (MM200 at 60m) = 10.9 m/s, Obukhov length: ~5000m (MM200 at 60m)

or by best fit to the measured inlet profiles (at MM200) if the participant considers that this can improve the results The computational domain must extend at least to X = ±4000 m in order to include the profilers upstream and downstream of the hill top and make sure that the hill wake is completely covered. The origin of the coordinate system should be placed at MM200 position [UTMX=513590, UTMY=5690182, Zone: 32U] with X pointing East, Y pointing North and Z pointing up.

Output data

The simulated validation profiles consist on vertical profiles at mast and profiler positions of velocity components (U,V,W) and turbulence kinetic energy (tke). In addition, a two-dimensional field along the 217° transect crossing the location of the 200m met mast (MM200) should be provided.

The profiles should have the following order: X(m), Y(m), Z(m), U(m/s), V(m/s), W(m/s), tke(m2/s2).Use the file naming and format convention described in the Windbench user's guide with profID = prof#, where # = [MM140, MM200, WP1, WP3, WP6], i.e. 5 output files per user and model run. Please provide profile data from bottom to top of the modelled domain.

Additionally, please provide the 2D fields (streamwise-vertical) field that is centred around the 200m mast, along the 217° transect, i.e. negative values indicate values towards the southwest, positive values towards the northeast and thus the wake of the hill. This field must be exactly along 217°, independent of the exact inflow wind direction.

Please provide the field as ASCII-file with the following order: Dist(m),Z(m),U(m/s), V(m/s), W(m/s), tke(m2/s2), where Dist is the distance from MM200 and Z(m) and Z is the height above terrain, or as a in a netCDF file. Please provide the field up to a height of at least 800m above terrain.

Please uplad your data compressed in the following shared folder:  https://b2drop.eudat.eu/s/oRPwdwwiQ9Naw5d

(only upload is alowed, your data is only shared with the benchmark manager)

Remarks

In order to evaluate the added value of model fine-tuning it is important that you describe how this is performed. Please report on the deviations with respect to default settings (e.g. those of the Kassel Benchmark I – Half-Blind or how you usually would set-up your simulations without knowing the field).
There are no guidelines on the definition of the computational mesh and also on how to model the forests. Please describe in detail if and how you have modelled the forest. Please also comment on how you integrate grid dependency in the evaluation process.
You can find the input and validation files as well as other background documentation here

All input data is stored in the following shared (B2Drop) folder: https://b2drop.eudat.eu/s/UB498d5gMcU7sSO

Timeline

  • Submit your simulation results until February, 16th, 2018 
  • The results will be discussed at NEWA's 3rd annual meeting in Oldenburg, 12-16 March 2018

Terms and Conditions

The benchmark is offered to participants of the NEWA (New European Wind Atlas) project and anyone else interested in participating.