為了探討亞重力波生成的特性，本文乃在國立成功大學水工試驗所之大型斷面水槽(300m*5m*5.2m)進行實驗量測分析。本文將坡度1/10及1/20的規則波及三波試驗以無因次之參數去作分析比較。文中以相同相對水深之規則波試驗去做比較，在頻率方面，波浪尖銳度改變，其截斷頻率及亞重力波頻率無太大的改變，而坡度改變，亞重力波頻率會出現移至低頻的現象。而以相對初始波浪尖銳度去比較，發現週期越長，截斷頻率與亞重力波頻率也有移至低頻的現象。且分別找出坡度1/10及1/20規則波、三波之截斷頻率、亞重力波最大能量頻率與主頻之比希望能瞭解各頻率之間之關係。在能量方面，亞重力波能量會出現週期性的起伏現象，而初始波浪尖銳度增大，亞重力波能量起伏會跟著變小。而水深變淺導致碎波時，波浪主頻能量則會大幅衰減，亞重力波能量會大幅增加。且三波作用下的截斷頻率及亞重力波最大能量頻率試驗分析結果顯示較規則波分布散亂，表示副頻會影響截斷頻率及亞重力波最大能量頻率分布。而至於其他坡度的比較分析將於日後實驗完成後再進行探討，以瞭解亞重力波的生成機制。

　　In order to investigate the characteristics of infra-gravity waves, a series of systematic and well- controlled regular wave and imposed side-bands are conducted on 1/10 and 1/20 slope bottoms in a super wave flume(300m *5m*5.2m) at Tainan Hydrulics Laboratory (THL).
　　In the regular wave tests at the same of slope bottom, the cut off frequency and the frequency of the maximum energy of infra-gravity wave are not changed for different initial wave steepness. But the frequency of infra-gravity wave will move to lower frequency if the slope becomes mild. From the comparison of the regular wave tests at the same of initial wave steepness, the cut off frequency and the frequency of infra-gravity wave moved to lower frequency if the wave period became longer. It is noticed that as waves break on the slope bottom, the energy of fundamental frequency will decrease substantially and the energy of infra-gravity wave will relatively increase. It is also found that the cut off frequency and the frequency of infra-gravity wave in the tests of side-bands are more disordered and complicated than in the tests of regular waves due to the effects of sidebands.
　　Further, the relationships between the cut off frequency, the frequency of the maximum energy of infra-gravity wave, and the fundamental frequency are also obtained in this paper.

1. Baldock T.E., Huntley, D. A., Bird, P. A. D., O’Hare T.,and Bullock G. N., “Breakpoint generated surf beat induced by bichromatic wave group”,Coastal Eng.39,213-242,2000.
2. Bower, E.C. “Low frequency waves in intermediate water depths”,Proc.of 23rd ICCE,832-845,1992.
3. Elgar, S., T. H. C. Herbers, M. Okihiro, J. Oltman-shay,and R. T. Guza,. “Observation of infragravity waves. ” , J. Gerphys. Res., 97(C10), 15573 - 15577,1992.
4. Elgar, S. and R. T. Guza, “Infragravity-frequency(0.005-0.05Hz)motions on the shelf. Part I：Forced waves”,J. Phys. Oceanogr., 24917-24927,1994.
5. Goda, Y., “A unified nonlinearity parameter of water waves”,Rept. Port and Harbour Res.Inst.,22(3),3-30,1983.
6. Guza, R. T., and E. B. Thorton, “Observation of surf beat”, J. Geophys. Res., 90(C2),3161-3172,1985.
7. Holman, R. A., “Infragravity energy in the surf zone”, J. Geophys. Res.,86(C7),6442-6450,1981.
8. Huntley, D. A., R.T. Guza, and E. B. Thomton, “Field observations of surf beat,1,Progrressive edge waves” J.Geophys.Res.,86(C7),6451-6466,1981.
9. Nakamura, S. and Katoh. K., “Berm erosion due to long period waves” ,Proc. of 22nd ICCE,2073-2086,1990.
10. Katoh, K. and S.N., “Generation of infagravity waves in breaking process of wave groups” ,Proc, of 23rd ICCE,990-1003,1992.
11. Longuet-Higgins, M., and R.Stewart, “Radiation stress and mass transport in gravity waves, with application to ‘surf beat’ ”,J. Fluid Mech., 13, 481 –504, 1962.
12. Okihiro, M., R. T. Guza, and R. J. Seymour, “Bound infragravity waves”,J. Geophys. Res.,97(C7),11453-11469,1992.
13. Oltman-shay, J.,and R.T.Guza, “Infragravity edge wave observations on two California beaches”,J. Phys. Oceanogr.,17,644-663,1987.
14. Okihiro,M., R.T.Guza, “Infragravity energy modulation by tides” , J. Geophys. Res.,100(C8)16143-16148,1995.
15. Symond, G., D. A. Huntley, and A.J.Bowen, “Two-dimensional surf beat：Long wave generation by a time-varying breakpoint”, J. Geophys. Res., 87, 492-498,1982.
16. Sorensen,O.R.Schaffer,H.A., “Surf zone dynamics simulated by a Boussinesq type model. Part Ⅱ: surf beat and swash oscillations for wave groups and irregular waves”,Coastal Eng.32,289-319,1997.
17. 林均樺, “長波生成之實驗量測”,碩士論文,成功大學,2004
18. 湯麟武, “波浪學綱要”,1986
19. 郭金棟, “海岸工程”中國土木水利工程學會,1988
20. 郭一羽, “海岸工程學”,2001
21. 許泰文, “近岸水動力學”,中國土木水利工程學會,2003
22. 蘇仕峰, “亞重力波之觀測”,碩士論文,成功大學,1999