VALIDATION DATA FOR LES-BASED FLOW AND DISPERSION MODELS

Transcription

1 VALIDATION DATA FOR LES-BASED FLOW AND DISPERSION MODELS Rasmus Fischer, Ilona Bastigkeit, Bernd Leitl, Michael Schatzmann University of Hamburg, Meteorological Institute, Environmental Wind Tunnel Laboratory (EWTL) MetStröm Hamburg,

2 MOTIVATION RANS-based as well as LES-based codes have to be validated carefully quality and accuracy of used test data significantly affect the results of model validation procedures LES-codes have different requirements on validation data quality and quantity

3 MOTIVATION RANS-based models LES-based models: variety of test data already available (e.g. CEDVAL, Leitl, 2) instantaneous, time-dependent variables required for inflow and boundary conditions test data usually not available can be obtained from adequate wind tunnel measurements

4 EXPERIMENTAL SETUP Facilities two boundary layer wind tunnels different scales flow and dispersion measurements wind tunnel WOTAN test section length 8 m test section width 4 m ceiling height m turn tables 2 BLASIUS.5 m.5 m m

5 EXPERIMENTAL SETUP Instrumentation Dispersion-Measurements: 2 D / 3 D Laser-DopplerAnemometry (LDA) Flame Ionisation Detectors (FID) 2 D / 3 D Particle Image Velocimetry (PIV) EWTL@ ZMAW.DE University of Hamburg trigger signal [V] 5 c [ppm] Flow-Measurements: wt time [s] ewtl@zmaw.de

6 PRELIMINARY WORK REQUIREMENTS PROFILE FOR LES VALIDATION DATA systematic tests of numerical codes test cases with different complexities Requirements profile for LESvalidation data requirements with regard to the quality of the validation data detailed documentation complete validation data base

7 TEST CASES WITH DIFFERENT COMPLEXITIES complexity complexity complexity 2 complexity 3 ewtl@zmaw.de

8 TEST CASES WITH DIFFERENT COMPLEXITIES Michel-Stadt Y [mm] X [mm] ewtl@zmaw.de

9 COMPLETE VALIDATION DATA BASE approach flow conditions play an important role and have to be carefully documented accelerated BL decelerated BL constant cross section very rough BL no BL simulation reference BL U mean /U ref [-] U'W' mean /U ref 2 [-]

10 COMPLETE VALIDATION DATA BASE 3 approach flow conditions play an important role and have to be carefully documented accelerated BL decelerated BL constant cross section higher turbulence BL no BL simulation reference BL U mean /U ref [-] U'W' mean /U 2 ref [-]

11 COMPLETE VALIDATION DATA BASE flow measurements within the model area at sufficiently dense grid of observation points y/h [-] x/h [-] u mean [m/s] Häufigkeit [-].42 class [m/s] 3. m.5 m.5 m 3. m Häufigkeit [-].5 class [m/s] Häufigkeit [-] Häufigkeit [-] Häufigkeit [-] Häufigkeit [-] Häufigkeit [-].34 class [m/s].4 class [m/s].44 class [m/s].4 class [m/s].22 class [m/s] Häufigkeit [-].46 class [m/s] Häufigkeit [-].56 class [m/s] 3. m.5 m.5 m 3. m

12 COMPLETE VALIDATION DATA BASE flow measurements within the model area at sufficiently long time series 4 5 s 9 s.8.8 frequency [-] frequency [-] v [m/s] s frequency [-] frequency [-] v [m /s] s v [m/s] v [m /s]

13 COMPLETE VALIDATION DATA BASE flow measurements within the model area at sufficiently long time series 4 5 s 9 s.8.8 frequency [-] frequency [-] v [m/s] s frequency [-] frequency [-] v [m /s] s -2-2 v [m/s] -2-2 v [m /s]

14 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA verified automated data processing due to the huge amount of data (archiving of time series) calibration of instrumentation at regular intervals

15 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA minimizing the longitudinal pressure gradient along the wind tunnel (verification of the constant shear layer) test of Reynolds Number independence of flow and dispersion lateral homogenity of the approach flow: standard deviation < 2% University of Hamburg U mean /U ref [-] Y fs

16 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA 5 repeatability of the results: average standard deviation < 2% U mean / U ref [-] standard deviation Umean/Uref [%] Iu [%] average

17 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA UV-flow measurements 2 Modellgebiet Intensivmessfeld vertikale Profile Y fs X fs V mean / U ref [-]

18 DETAILED DOCUMENTATION OF THE VALIDATION DATA methods of data preparation and form of data archiving documentation of boundary layer setup CEDVAL-LES complexity complexity complexity 2 complexity scale :5 scale :3 scale : MS model setup ST statistics wind UV TS time series FL flow data SPEC spectra wind UẈ.. FLUC fluctuations of winddirection U-component V-component

19 DETAILED DOCUMENTATION OF THE VALIDATION DATA MS model setup size of modeled area location and orientation of reference coordinate system measuring grid / location of measuring points measurement instruments detailed information about emission sources Information on geometry of test cases

20 COMPARISON: WIND TUNNEL - LES.4 2 WT BL3 LES bl3b_m_ts2.3 alpha field theory WT BL3 LES bl3b_m_ts2 - d U mean /U m [-] α [-] z alpha Zo WT BL LES bl3b_m_ts2.3.3

21 COMPARISON: WIND TUNNEL - LES turbulence intensity 2 WT BL3 LES bl3b_m_ts2 - d I U [%]

22 CONCLUSION generating valdation data for LES-based flow and dispersion models is a non-trivial task requirement of higher experimental efforts with respect to data collection, data handling and quality assurance However: carefully designed tests under controlled boundary conditions in wind tunnels can deliver data qualified for validations of LESmodels

23 Thanks for your attention!

24 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA (U/U ref ) mean [-] temporal representativeness of locally measured time series: confidence interval of mean values > 98% acquisition time [s] scale :225 test case: z = ½ H 27 s in model scale 7 h in full scale F ra m e 8 M a y 2 7 at_mean sufficient number of repetitive realizations for puff dispersion E n s e m b le s iz e

25 REQUIREMENTS CONCERNING THE QUALITY OF VALIDATION DATA UV-flow measurements 2 Modellgebiet Intensivmessfeld vertikale Profile Y fs X fs V mean / U ref [-]

26 COMPARISON: WIND TUNNEL - LES turbulent fluxes turbulence intensity 2 2 WT BL3 LES bl3b_m_ts2 WT BL3 LES bl3b_m_ts2 - d U'W' mean /U 2 m [-] - d I U [%]

27 Daten-Aufbereitung und Archivierung CEDVAL-LES complexity complexity complexity 2 complexity scale :5 scale :3 scale : MS model setup ST statistics wind UV TS time series FL flow data SPEC spectra U-component V-component wind UẈ.. FLUC fluctuations of winddirection

28 Beispiel complexity scale :5 scale :3 scale :225 Rauigkeits- Klasse (VDI) mäßig rau rau sehr rau z (Natur-Maßstab) Alpha [-] Maßstab :5 :3 :225 α [-] field data theory moderately rough rough very rough z

29 Beispiel MS model setup Y [mm] X [mm]

30 Beispiel TS time series alle Zeitserien dimensionslos Header Information: Windkanal Maßstab Referenz Windgeschw., Länge und Höhe mittl. Windrichtung Mess-Ort

31 Beispiel FLUC fluctuations of winddirection [-] f S UU (f,z) / σ U 2 TS time series SPEC spectra very rough boundary layer z=25m z=38m z=85m Kaimal z=85m Simiu z=85m Karman z=85m normalized frequency of occurrence lateral fluctuations in wind direction [deg] Windfluktuationen Spektren der TKE Daten-Header = 25m = 5m = m = 2m f z / U [-]

32 Beispiel ST statistics statistische Informationen aller Einzel-Zeitserien einer Messreihe Daten-Header

33 Beispiel ST statistics 9 6 moderately rough rough very rough moderately rough rough very rough U mean /U ref [-] 3 mittlere Windprofile Profile der I U [%] Turbulenzintensitäten

34 Beispiel 3 ST statistics constant shear layer moderately rough rough very rough U'W' mean /U 2 ref [-] 2 z m (theory) z. m (theory) z. m (theory) z. m (theory) field data (low z ) field data (high z ) moderately rough rough very rough 2 3 L UX integralen Längenmaße turbulente Impulsflüsse