JM MIER 3D LDV Measurements in Oscillatory Boundary Layers · UNIVERSITY OF ILLINOIS AT...

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

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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


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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


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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


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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.


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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


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CHALLENGE: LDV SYSTEM IN 3D CONFIGURATION

• Closed section

• Limited optical access

• Under pressure

• Window thickness

• Refraction

• Traversing 2 probes

• Alignment

• Bubbles

• Reflections

• Seeding particles


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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


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FOCAL DISTANCE CORRECTION: WATER CONTAINER


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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


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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


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QUESTIONS

JM MIER 3D LDV Measurements in Oscillatory Boundary Layers · UNIVERSITY OF ILLINOIS AT...

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