1. STRONGLY NONLINEAR INTERNAL WAVES IN LAKES: GENERATION, TRANSFORMATION, MEROMIXIS Grant INTAS 03-51-3728 EXPERIMENTS ON TRANSFORMATION AND BREAKING OF INTERNAL SOLITARY WAVES BY LOCAL CONSTRICTION Institute of Hydromechanics of NAS of the Ukraine Kiev, Ukraine Ph. (38044) 455-64-34; Fax: 38044 – 455-6432); e-mail: vin @ visti.com

2. EQUIPMENT BASIN (length 7 m; width 0.40 m; height 1.5 m) ADC2, ADC3, ADC4 – sensors of capacity WAVE GENERATORADC 5, ADC6 – sensors of conductivity

3. MODELS OF CONSTRICTIONS SHAPE OF CONSTRICTIONS L=120 cm L=97 cm B=19.5 cm B=32 cm L=177.5 cm, B=19.5 cm (with rectangular inserting)

4. PARAMETERS - phase speed of an infinitely long, infinite- simally small waves - solitary wave speed (KdV) - speed of strongly nonlinear solitary wave Wave length: 1. - half-amplitude point:Total energy 2. In the reference frame moving with ISW Conservation law

5. PROFILES ( ) sensor of conductivity CALIBRATION 04.11, run104.11, run 2

6. DATA SCHEME 0F EXPERIMENT CALIBRATION adc4adc2 adc1 adc0

7. VISUALIZATION 04.11 (a=8.2 cm)

8. VISUALIZATION 26.10 (a=6.2 cm)

9. VISUALIZATION 02.11 (a=5.3 cm)

10. SHAPE a=8.2 cm ( super-critical regime) a=5.3 cm (sub-critical regime)

11. RESULTS (B=19.5 cm) Scheme of experiment 02.11, B=19.5 cm, run1, =30 cm, =2.16 cm, =0.6 cm Scheme of experiment 26.10, B=19.5 cm, run1, =30 cm, =2.8 cm, =1.1 cm ac c0c* E*g adc4_ i 5.320.811.15.511.743.2827..9 adc3_ i 7.9 adc2_ i 5.3 adc1_ p 3.919.3c*=105.51037.4415.7 adc0_ p 3.512.811.3 (c*=9.5) 5.59.531.0244 ac c0c* E*g adc4_ i 6.2321.711.36.212.344.31215 adc3_ i 7.36 adc2_ p 6.4827.154.31676 adc1_ p 5.123c*=11.26.211.2 adc0_ p 3.3813.3(c*=9.5)6.29.526.3202

12. PROFILES ( ) SCHEME 0F EXPERIMENT 07.12, run107.12, run2

13. DATA run1, a=8.1 cm adc3 adc2 adc1 adc0 SHAPE adc3 adc0

14. VISUALIZATION 07.12 (a=8.1 cm)

15. VISUALIZATION 09.12 (a=4.4 cm)

16. VISUALIZATION 13.12 (a=3.9 cm)

17. CONCLUSIONS 1.It is found that effect of constriction results in the substantial transformation of flow, instability of solitary waves and strong dissipation. 2.Passed and reflected solitary waves are generated due to interaction of solitary waves with constriction. The energy of these waves are considerably less than energy of initial wave. The interaction is an effective mechanism of decreasing of scales. 3.It is shown that sharp steepening is accompanied be the growth of the amplitude and subsequent breaking of wave. At strong interaction the dividing of wave depending of amplitude are observed: the leading part go through narrowing but last part is trapped and forms the reflected wave and “tail” of the leading part. 4.After passing the narrowing the system of vortices arise in convergent part of flow that is the effective mechanism of dissipation. 5.The irregularity of amplitude distribution in cross section in front of constriction is occurred. This is the main reason of transformation of flow near narrowing, dividing of strongly non-linear wave and trapping of rear part.