We are interested in the study of mixing with salinity flux in coastal areas due to turbulence and wave action. Previous studies (Petrolo & Woods, 2019, Petrolo & Longo, 2020) had shown the efficiency of turbulence due to a stirrer in generating a salinity flow capable of mixing, in the absence of fluid inputs and subtractions. The mixing also occurs, depending on the level of turbulence, for low flows of fresh/saline water, while high flows promote a more stable stratification, with vertical flow that can generally be limited by the intensity of the sources and the intensity of the turbulence. The problem is analysed here in the case where the source of turbulence is wave action. The wave field is affected by turbulence generated at the surface, very intense in the presence of breakers, and at the bottom if the waves are in shallow water; the turbulence can spread affecting part or all of the liquid column. In a focial scheme, with fresh water from the river and salt water in the sea basin, the action of the waves on the mixing of salinity and, with different intensity on the mixing of chemicals and gas, is of great importance. The study was carried out in the laboratory in a channel with a wave generator generating regular waves in a fluid column initially stratified with salt water at the bottom and fresh water at the top. The surface dynamics are accompanied by varied interface dynamics, with slow and progressive diffusion of the salty water into the fresh water. Measurements were made photographically to identify the interface and density gradients; with a Doppler profilometer for velocity field; and with a conductivity meter to measure local salinity at a data rate of 20 Hz. The synthetic schlieren method described in Longo et al (2016) was used, with a mask of randomized array of dots mimicking the tracers in Particle Image Velocimetry (PIV) technique and positioned between the light source and the channel. A PIV software was adopted to measure the apparent displacement of the dots, which is proportional to the square of the buoyancy frequency.

Experiments on Buoyancy Transfer in a two-layer System in Transient State / Chiapponi, Luca; Petrolo, Diana; Longo, Sandro Giovanni. - STAMPA. - (2022). (Intervento presentato al convegno 39th IAHR World Congress - From Snow to Sea tenutosi a Granada (Spain) nel 19-24 June 2022) [10.3850/IAHR-39WC2521711920221881].

Experiments on Buoyancy Transfer in a two-layer System in Transient State

Luca Chiapponi
Membro del Collaboration Group
;
Diana Petrolo
Membro del Collaboration Group
;
Sandro Longo
Membro del Collaboration Group
2022-01-01

Abstract

We are interested in the study of mixing with salinity flux in coastal areas due to turbulence and wave action. Previous studies (Petrolo & Woods, 2019, Petrolo & Longo, 2020) had shown the efficiency of turbulence due to a stirrer in generating a salinity flow capable of mixing, in the absence of fluid inputs and subtractions. The mixing also occurs, depending on the level of turbulence, for low flows of fresh/saline water, while high flows promote a more stable stratification, with vertical flow that can generally be limited by the intensity of the sources and the intensity of the turbulence. The problem is analysed here in the case where the source of turbulence is wave action. The wave field is affected by turbulence generated at the surface, very intense in the presence of breakers, and at the bottom if the waves are in shallow water; the turbulence can spread affecting part or all of the liquid column. In a focial scheme, with fresh water from the river and salt water in the sea basin, the action of the waves on the mixing of salinity and, with different intensity on the mixing of chemicals and gas, is of great importance. The study was carried out in the laboratory in a channel with a wave generator generating regular waves in a fluid column initially stratified with salt water at the bottom and fresh water at the top. The surface dynamics are accompanied by varied interface dynamics, with slow and progressive diffusion of the salty water into the fresh water. Measurements were made photographically to identify the interface and density gradients; with a Doppler profilometer for velocity field; and with a conductivity meter to measure local salinity at a data rate of 20 Hz. The synthetic schlieren method described in Longo et al (2016) was used, with a mask of randomized array of dots mimicking the tracers in Particle Image Velocimetry (PIV) technique and positioned between the light source and the channel. A PIV software was adopted to measure the apparent displacement of the dots, which is proportional to the square of the buoyancy frequency.
2022
Experiments on Buoyancy Transfer in a two-layer System in Transient State / Chiapponi, Luca; Petrolo, Diana; Longo, Sandro Giovanni. - STAMPA. - (2022). (Intervento presentato al convegno 39th IAHR World Congress - From Snow to Sea tenutosi a Granada (Spain) nel 19-24 June 2022) [10.3850/IAHR-39WC2521711920221881].
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2928213
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact