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UNIVERSITY OF ILLINOISAT URBANA‐CHAMPAIGN
3D LDV MEASUREMENTSIN OSCILLATORY BOUNDARY LAYERS
Jose M. Mier [email protected]
Marcelo H. Garcia [email protected]
December 7th, 2012
Ven Te Chow Hydrosystems LaboratoryCivil & Env. Engineering Dept.
AGU Fall meeting 2012Session EP52A: Advances in Field and Laboratory Measurement
Methodologies for Quantifying Geophysical Flows I
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
2
Sediment Transport
Bed Morphology
MOTIVATION
OSCILLATORY FLOWS AT THE BOTTOM OF THE SEA:Getting to understand the processes of interaction between fluid and sediment.
Fluid in motion
Velocity measurements
VIDEO LOWST
• Mean flow
• Turbulence
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
3
THE OSCILLATORY BOUNDARY LAYER
From Jensen (1988)
Outer, inviscid region
Inner, viscous region
(boundary layer)
u = U = f (ωt)
u = f (z , ωt)
Bottom Shear Turbulence upward propagation boundary layer
τ = f (z , ωt)
τ = f (ωt)
u
Exp. Y6: Smooth bed. Rew = 1.7 x 105
z
VIDEO
From Carstensen et al. (2010)
VIDEO
Smooth bed, Rew = 3.0×105
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
4
PREVIOUS EXPERIMENTAL WORK
OSCILLATORY FLOW EXPERIMENTSPrevious studies
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07
Rew
a/k s
Jonsson (1980)
Hino et al. (1983)
Sleath (1987)
Jensen (1988)
Jensen (1988) - tau_b only
Kamphuis (1975)
Pedocchi (2009)
SMOOTH
MORE TURBULENT
MO
RE
RO
UG
H
SMOOTH TURBULENT
ROUGH TURBULENT
SMOOTH LAMINAR
TRA
NSI
TIO
N
TRANSITION
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
5
RESEARCH GOAL
OSCILLATORY FLOW EXPERIMENTSPrevious studies and present work
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07
Rew
a/k s
Jonsson (1980)
Hino et al. (1983)
Sleath (1987)
Jensen (1988)
Jensen (1988) - tau_b only
Kamphuis (1975)
Pedocchi (2009)
SOT + LDV
SOT + PIV (Anna)
LOWST + LDV
SMOOTH
MORE TURBULENT
MO
RE
RO
UG
H
SMOOTH TURBULENT
ROUGH TURBULENT
SMOOTH LAMINAR
TRA
NSI
TIO
N
TRANSITION
• Characteristics of the mean flow and turbulence in the laminar-turbulent transition of the oscillatory boundary layer with smooth bed.
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
6
12 m
pistons
LARGE OSCILLATORY TUNNEL
Experimental setup:fixed, flat, smooth, PVC floor
80 cm
60 cm
Setup team: Andy Waratuke, Andrew Rehn, Nicholas Möller, CEE shop
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
7
CHALLENGE: LDV SYSTEM IN 3D CONFIGURATION
• Closed section
• Limited optical access
• Under pressure
• Window thickness
• Refraction
• Traversing 2 probes
• Alignment
• Bubbles
• Reflections
• Seeding particles
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
8
3D LDV TRAVERSING WITH 2 PROBES
Focal distance changes for top probe when traversing up
CROSS-SECTION VIEW
Focal distance is preserved for top probe when traversing up
Watercontainer
Submersibleprobe
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
9
FOCAL DISTANCE CORRECTION: WATER CONTAINER
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
10
U velocity contours:
RESULTS: MEAN VELOCITY
Exp. X6: Smooth bed, Rew = 6.4 x 105
log
• Symmetry both half-cycles
• Phase lead inside boundary layer
• Non-sinusoidal velocity inside boundary layer
Phase lead
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
11
TKE contours:
RESULTS: TKE
log
Exp. X6: Smooth bed, Rew = 6.4 x 105
• Dominated by U contribution
• Good symmetry
• Peak turbulence near the bed
• Phase lead with Uom
• Upward propagation in time
• Upper limit of boundary layer thickness
Jose M. Mier and Marcelo H. GarciaDecember 7th, 2012
12
QUESTIONS