Experimental Investigation on Mode-2 Internal Solitary Wave and its Induced Flow Field in Continuous Density Pycnocline
The experimental investigation on the Mode-2 internal solitary waves(ISW)and its induced flow field in the continuous density pycnocline are carried out in a large stratified flume.The experimental simulation of the Mode-2 ISW in the continuous pycnocline is realized by using the principle of stratified fluid gravity collapse.The conductivity probe array and particle image velocimetry(PIV)are used to measure the Mode-2 ISW and its wave induced flow field.The geometrical characteristics of Mode-2 ISW waveform in the continuous pycnocline is obtained,and the non-uniform structures of the wave-flow are obtained,and the influence of wave amplitude variation on the characteristics of wave propagation factor and wave-flow field of Mode-2 ISW are obtained.The research shows that the geometric waveform of the Mode-2 ISW in the continuous pycnocline is presented as the convex and concave oval wave packets,and the non-uniform vertical structure of waveform is characterized by the non-uniform changes of the amplitude and wavelength with water depth.The convex and concave regions of the Mode-2 ISW packet form counterclockwise and clockwise circulations respectively,and the combination of the two forms a pair of upper and lower antisymmetric circulations to propagate forward together.The wave velocity of the Mode-2 ISW increases with the increase of wave amplitude,and the wavelength decreases with the increase of wave amplitude.The magnitudes of the horizontal and vertical flow velocity are positively correlated with the characteristic wave amplitude,and the former magnitude is greater than the latter one.The research results can improve the understanding of the Mode-2 ISW and its wave-induced flow field under the actual ocean stratification conditions.
Continuous density pycnoclineMode-2 internal solitary waveNon-uniform vertical structureWave induced flow field
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