Tsunami Induced Turbulent Coherent Structures Tsunami Induced TCS Nearbed TCS Shallow horizontal TCS...
-
Upload
esperanza-finnell -
Category
Documents
-
view
235 -
download
3
Transcript of Tsunami Induced Turbulent Coherent Structures Tsunami Induced TCS Nearbed TCS Shallow horizontal TCS...
Tsunami Induced Turbulent Coherent Structures
Tsunami Induced TCS
Nearbed TCS Shallow horizontal TCS Near-surface breaking TCS
Harbors and Ports
Pick up and Liquefaction
Scour
z
y
x
Diane Foster (UNH), Pat Lynett (USC), and Tom Hsu (Udel)Sponsor: NSF CMMI - 1135026
Tsunami Induced Turbulent Coherent Structures
Nearbed TCS
Pick up and Liquefaction
Scour
With significant intellectual contributions from Donya Frank and Meagan Wengrove
z
y
x
Observations
• NEESR– Large Wave Flume– O. H. Hinsdale Wave
Research Lab• Wave Conditions– Long Waves– Short Waves & Long
Waves– Short Waves
Observations
• BL measurements– u, v, w – 1 mm range bins over 3 cm– 100 Hz
• Bed Roughnesses– Flat– Rippled– Rough
Observations
• BL meaurements– u, v, w – 1 mm range bins– 100 Hz
• Bed Roughnesses– Flat– Rippled– Rough
Single solitary over a flat smooth bed
u (m
/s)
w (m
/s)
Single solitary over a flat smooth bed
u (m
/s)
w (m
/s)
Reynolds Stress Estimate
u
Reynolds Stress Estimate
u
t
Rough Bed
• Flat• Rippled• Rough
Smart Sediment Grains
• Dimensions: – 2.5 x 1.5 x 1.4 cm
• Components: – 2 triaxial accelerometers, memory
card, battery and wireless transmitter.
• Enclosure:– 4.4 cm Delrin plastic sphere– Combined specific gravity of 1.3
Overview of Test Results• Preliminary tests– Low noise floor: 0.3 m/s2
– Accurate reproduction of oscillations with reference accelerometer
• Large-scale wave tank tests– Height=0.20m, Period=3s– Incipient motion at Shields
of 0.025 and Sleath of 0.12– Results indicated plug flow
sediment transport regime
• X-Force Balance yields: where:
Incipient Motion
b
T
p
> ~ 0.37
Sleath (1999)
€
S =ρUoω(ρ s − ρ )g
€
θ = ρu*2
(ρ s − ρ )gd50
p +∂p∂xdx
S +θd50
h> kCb(1+α)
> 0.04~0.08 incipient motion > 0.8 sheet flow
S > 0.29 plug flow
• X-Force Balance yields: where:
Incipient Motion
b
T
p
> ~ ?
Sleath (1999)
€
θ = ρu*2
(ρ s − ρ )gd50
p +∂p∂xdx
S +θd50
h> kCb(1+α)
> 0.04~0.08 incipient motion > 0.8 sheet flow
S > 0.1 plug flow
€
S =ρ Du∞ Dt(ρ s − ρ )g
S +θd50
h
S +θd50
h
Thank you• Boundary Layer
observations over fixed beds
• Particle accelerations of incipient motion and rolling grains