1. an introduction to terra-incognita
DESCRIPTION
A LARGE EDDY SIMULATION PERSPECTIVE OF TERRA-INCOGNITA. 1. An introduction to Terra-Incognita . 2. Rough wall SGS dynamics and Terra-Incognita. 3. Large-eddy simulation (LES). 4. A potpourri of LES with complex boundaries . is the characteristic length scale of - PowerPoint PPT PresentationTRANSCRIPT
1. An introduction to Terra-Incognita
4. A potpourri of LES with complex boundaries
3. Large-eddy simulation (LES)
A LARGE EDDY SIMULATION PERSPECTIVE OF TERRA-INCOGNITA
2. Rough wall SGS dynamics and Terra-Incognita
Kaimal & Finnigan (1994)
Increasing stratification z/L
is the characteristic length scale of the vertical velocity spectrum
convective stable
convective stable
Mes
o lim
itLE
S li
mit
A LOOK AT FILTERING
SIMPLE (CHEAP) FILTERING EXAMPLE …
Data in the atmospheric surface layer
MOVING BETWEEN MESO LIMIT AND LES LIMIT
MOVING BETWEEN MESO LIMIT AND LES LIMIT
MOVING BETWEEN MESO LIMIT AND LES LIMIT
MOVING BETWEEN MESO LIMIT AND LES LIMIT
MESO limit
MOVING BETWEEN MESO LIMIT AND LES LIMIT
Can we use targeted observations to provide insight as to the nature of SGS motions in high Re PBLs, and the Terra-Incognita regime?
HATS CONFIGURATIONS
Wide
Narrow
U
``2D plane of turbulence”
AN EXAMPLE OF LATERAL (Y) FILTERING
U
AN EXAMPLE OF LATERAL (Y) FILTERING
U
AN EXAMPLE OF LATERAL (Y) FILTERING
WHAT DO SGS STATISTICS FROM OBSERVATIONS LOOK LIKE?
Isotropic
HATS ARRAYS
OHATS FIELD CAMPAIGN
ASIT
Laser altimeters
18 CSATS
275 hours ``12 days of data” analyzed
OHATS
HATS
Meso Limit! What produces and ?
WHAT ARE THE FLUX EQUATIONS?
SGS scalar flux
0
Isotropic production
Anisotropic productionPressure destruction
0 0
00
Eddy viscosity model
Rotta model
Time scale
Eddy viscosity model
C=0.3 (Hatlee & Wyngaard, 2006)
Anisotropic model
SGS MOMENTUM FLUXES
Considerable Algebra !
Isotropic production
Anisotropic deviatoric productionPressure destruction
Rotta model
Time scale
0
0
00
OHATS
HATS
MESO Limit LES Limit
Measure of scale separation
OHATS
HATS
MESO Limit LES Limit
Measure of scale separation