Measuring run-up and bed shear-stress using long-stroke wavemaker

1. Measuring run-up and bed shear-stress using long-stroke wavemaker Hong-Yueh (Peter) Lo Nimish Pujara Professor Philip L.-F. Liu's Group Cornell University

2. Acknowledgments Supported by: NEESR-SD:  Measuring Runup and Bed Shear Stress Using Long Stroke Wave-Makers EAGER:  Developing and Testing Algorithms for Generating Leading Tsunami Advice and Assistance from: Philip Liu Yong Sung Park Harry Yeh Melora Park & all OSU lab staff

3. Presentation Outline · Introduction · Experiments at Oregon State University · Experiments at Cornell University · Discussion on run-up results · Shear-plate project 1/23

4. Introduction · Knowledge in wave run-ups and bed shear-stress is crucial for coastal protection · Solitary waves are increasingly considered as an inaccurate tsunami model · Studying the effects of multiple waves and different tsunami models may be helpful · The new long-stroke wavemaker at Oregon State University enables the generation of various large-scale waves · Scale effects on trends can be examined by conducting experiments in different laboratory settings · A shear plate can directly measure near-bed shear-stress – the shear plate project 2/23

5. Introduction - Laboratories overview 0.8m wide, 12m long, 1:10 slope, Cornell University 3.7m wide, 104m long, 1:12 slope, Oregon State University 0.6m wide, 34m long, 1:20 slope, Cornell University 3/23

6. Experiments at Oregon State University O. H. Hinsdale Wave Research Laboratory – Large Wave Flume 4/23

7. Experiments at Oregon State University - Overview Facility: · 104m long x 3.7m wide x 4.6m deep ·4m stroke wave maker on one end of the flume ·1:12 sloped beach installed on the other end Experiments: ·Single solitary waves ·Double solitary waves ·Triple solitary waves ·Bores ·Leading-depression N-waves 5/23

8. Experiments at Oregon State University – Parameters & Setup 6/23

9. Experiments at Oregon State University – Single solitary waves Three cases: H/h = 0.2 H/h = 0.15 H/h = 0.1 7/23

10. Experiments at Oregon State University – Double solitary waves Four different H/h, with various separation time τ Sample video 8/23

11. Experiments at Oregon State University – Triple solitary waves Whole 4m stroke used H/h=0.1 Three different τ 9/23

12. Experiments at Oregon State University – Bores Solid line: Paddle trajectory for a solitary wave Dashed line: Paddle trajectory for a bore Two different H/h H/h=0.1 H/h=0.15 10/23

13. Experiments at Oregon State University – LDN waves Three different H/h Sample video 11/23

14. Experiments at Oregon State University – Repeatability · At least 30% of the experimental cases at OSU were repeated · Such run-up experiment is found to be highly repeatable from previous observation at Cornell University 12/23

15. Experiments at Cornell University 13/23

16. Experiments at Cornell University – Overview & Setup Experiments (all repeated at least once): ·Single solitary waves ·Double solitary waves · Bores 14/23

17. Discussion on run-up results – Single solitary waves · Single solitary wave run-ups compare well with existing studies*, yet the definition of run-up can cause discrepancy *Synolakis (1986), Briggs et al. (1995), Li & Raichlen (2000), and Hsiao et al. (2008) 15/23

18. Discussion on run-up results – Single solitary waves Dotted line: Synolakis' experimental maximum run-up on a 1:19.85 slope Dashed line: Synolakis' experimental average run-up on a 1:19.85 slope Circle: Cornell's experimental average run-up on a 1:20 slope 16/23

19. Discussion on run-up results – Double solitary waves 1:20 slope Solid markers: first run-up Hollow markers: second run-up Similar trend holds for 1:10 & 1:12 slopes 17/23 Sample video

20. Discussion on run-up results – Bores · Bores evolve as they propagate, and produce different run-ups Traveled distance: ~10λ~2.5λ~1.4λ 18/23

21. Discussion on run-up results – Bores · For propagation distance greater than about 10 wavelengths, bores cause same run-ups as single solitary waves with same H/h o: bores x: single solitary waves Tank with 1:10 slope & ~2.5λ travel distance Tank with 1:12 slope & ~1.4λ travel distance 19/23

22. Discussion on run-up results – Triple solitary waves & LDN · LDN waves seem to cause lower run-ups than single solitary waves 20/23

23. Reference Barnes, M. P., O’Donoghue, T. O., Alsina, J. M., and Baldock, T. E., (2009, Direct bed shear stress measurements in bore-driven swash, Coastal End., 56, 853-867 Briggs, M. J., Synolakis, C. E., Harkins, G. S., Hughes, S. A., 1995. Large-scale, three dimensional laboratory measurements of tsunami inundation. Tsunamis: Progress in Prediction, Disaster Prevention and Warning. Kluwer Academic Publishers, 129–149. Hsiao, S.-C., Hsu, T.-W., Lin, T.-C., Chang, Y.-H., 2008. On the evolution and run-up of breaking solitary waves on a mild sloping beach. Coastal Engineering 55, 975-988. Li, Y., Raichlen, F., 2000. Non-breaking and breaking solitary wave run-up. J. Fluid Mech. 456, 295–318. Madsen, P. A., Fuhrman, D. R., Schaffer, H. A., 2008. “On the solitary wave paradigm for tsunamis.” J. Geophys. Res., 113, C12012, doi:10.1029/2008JC004932. Synolakis, C. E., 1986. The run-up of solitary waves. J. Fluid Mech. 185, 523–545. Studying waves is a walk on the beach...

24. Auxiliary slides – Double solitary waves run-up, all Solid markers: first run-up Hollow markers: second run-up

25. Auxiliary slides – Double solitary waves run-up, R2/R1 Normalized - R2/R1 ∆: H/h=0.467 *: H/h=0.1 x: H/h=0.1374 □: H/h=0.15 ○: H/h=0.2 +: H/h=0.3 ◊: H/h=0.35

26. Auxiliary slides – Double solitary waves run-up, curve-fit

27. Auxiliary slides – Programmed run-up determination Sample video