Flow Visualization of Internal Waves and Wakes of a Streamlined Body in a Stratified Fluid

Bidokhti, Amin Ali Akbari; Bidokhti, A. A.

doi:10.18869/acadpub.jafm.68.225.24419

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…Some frequencies were recorded at different Froude numbers. In the frequency domain, at different Froude numbers, the number of peak points increased as Froude number was close to critical value, indicating an increase in the activity of internal waves, which is consistent with previous studies (Sutherland and Linden 2002;Glushko et al 1994;Bidokhti et al 2016;Abdilghanie and Diamessis 2013;Hopfinger et al 1991;Bidokhti and Britter 2002). Figure 12 compares the frequency spectral densities for different scenarios.…”

Section: Frequency Analysis Of Recorded Signalssupporting

confidence: 88%

“…8. The obtained results are in good agreement with theory and the study of Bidokhti et al (2016), as shown in the Fig. 8.…”

Section: Validation Of Experimentssupporting

confidence: 88%

“…In order to validate the experiments performed, the results from this study were compared with those found by Bidokhti et al (2016) suggesting the same quantized properties. The comparison results together with the linear theory (Eq.…”

Section: Validation Of Experimentsmentioning

confidence: 90%

“…For the first time, Ekman (1904) identified IWs generated by the motion of a ship. Sutherland and Linden (2002), Aguilar et al (2006), and Bidokhti et al (2016), have used various methods for formation of IWs by creating glass water channels with different dimensions and they have measured and studied the physical features of generated IWs. Some of these studies have been conducted on the feasibility of specific channels in experimental research.…”

Section: Introductionmentioning

confidence: 99%

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Internal Gravity Waves Spectrum Generated by a Cylindrical Body Moving in a Stratified Fluid

2020

JAFM

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Internal waves are abundant in stratified environments such as the atmosphere and the ocean. In this paper, the internal waves and turbulent wake effect of a cylindrical body in a linear stratified environment is investigated. In a glass tank with dimensions 3×1×0.5 (m), a linear stratification with buoyancy frequency (N) equal to 0.51 per second, was set up. Then a cylindrical body with 6 cm in diameter and 45 cm at length was towed in the fluid, using a computer controlled system. While changing the Froude (from 0.16 to 1.5) and Reynolds numbers of the flow, the effects of these changes were examined on the formation of the internal waves and wake of the cylinder. The internal waves generated were studied using shadowgraph technique and signal fluctuations were recorded. The results show that the presence of internal waves depend on changes of buoyancy frequency (N), Froude numbers, and Reynolds numbers of the flow. It was also found that with an increase up to the critical Froude number, the activity of internal waves and their wavelengths enhanced. Also, irregular long and short waves as well as turbulence of the environment were observed in the range of supercritical Froude numbers. In this study, the signals are recorded in domains of frequency and statistics. Using an ultra-fast salinity meter (densitometer) for recording signal frequencies it was found that increasing Froude number results in more combination of frequencies occurred in the environment. Based on the results of current experiments and previous studies, an equation was extracted to calculate the wavelength by parameters like velocity of body, maximum frequency value and propagation angle. The energy of wave spectrum increased up to a critical Froude number, and then decreased due to turbulence. The statistical distribution of signals recorded in most of the scenarios was normal.

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