On the current status of flow modelling for applications to advection

(1)

CarboEurope-IP meeting, Poznan, 8-12/10/2007

Yves Brunet and Sylvain Dupont

A L I M E N T A T I O N A G R I C U L T U R E

E N V I R O N N E M E N T

EPHYSE unit: Functional Ecology and Environmental Physics

On the current status of flow modelling for

applications to advection

(2)

+ Température Humidité…

Equations

(3)

Aquilon

Méso-NH

ARPS

Small scale : fluid mechanics

- Aquilon (Trefle, Bordeaux 1) Landscape scale : atmospheric models

- ARPS (USA)

Regional scale : atmospheric models - Méso-NH (Météo-France, LA)

(4)

canopy

landscape

region

Aquilon - ARPS

Méso-NH

Drag force approach

Roughness approach

A_f C_d

z₀ Models : spatial scales

Abaqus tree

(5)

canopy

landscape

region

Aquilon - ARPS

Méso-NH

Drag force approach

Roughness approach

A_f C_d

z₀ Models : spatial scales

Abaqus tree

(6)

Typical cases

•Flow over forest leading edges

•Flow over a forested hill

•Scalar dispersal

•Non-neutral flows

(7)

Large Eddy Simulation over

forest leading edges

(8)

Periodic conditions

20h 16h

1h

h=18m

Wind

Rayleigh damping layer

140m 70m

➔ Spatial resolution: 2 m

➔ Neutral atmosphere

Edge flow : computational domain

(9)

Edge flow : mean flow fields (1)

(10)

(11)

U / U_ref

σ_U/ U_ref

σ_w / U_ref

-u’w’ / U²_ref

Sk_u

Validation against Raupach et al.’s (1987) wind-tunnel measurements

Dupont and Brunet 2007a, BLM

(12)

ÎMean flow structure in the adjustment region

ÎInfluence of the vertical structure of the canopy

(ii)

(i) (iii) (iv)

EGZ

Equilibrium state TKE develops

x=0 h ~2 h ~6 h ~9 h

(13)

Application on Bray site : pine forest edge flow (1)

ARPS

North-west wind (edge)

South-east wind (canopy) Measurements

0h 4h 9h

north-west south-east

(14)

Large Eddy Simulation over a

forested hill

(15)

Periodic conditions Wind

Rayleigh damping layer

140m 70m

Forested hill: computational domain

L H h

ARPS ‘Furry hill’ wind-tunnel

H 30 m 0.15 m

L 84 m 0.42 m

h 10 m 0.047 m

a_f 0.16 m^-1 10 m^-1

c_d 0.2 0.68

24L

Equivalent H/L, H/h and c_da_fh

(16)

Outer region

Inner region

Recirculation

Wake region

Forested hill: LES (2m x 2m horizontal resolution)

(17)

(18)

(19)

(20)

u/u_*

u’w’/u_*²

tke/ u_*²

(21)

u’²/u_*

w’²/u_*²

Sk_u

Sk_w

(22)

u/u_*

u’w’/u_*²

tke/ u_*²

Forested hill: k-ε

(23)

Scalar dispersal

(24)

Dupont et al. (2006) Agri. For. Meteor.

Maize pollen dispersal at short distance

Maize target field a) Montargis

0 3 10 50 x(m) h_m

Δh_t

Maize source plot

l_m

Bare soil

Î Validation

Î Impact of heterogeneities on maize pollen dispersal functions (integration into statistical models)

Î ARPS + pollen