TY - JOUR
T1 - A new approach to understanding fluid mixing in process-study models of stratified fluids
AU - Hartharn-Evans, Samuel George
AU - Stastna, Marek
AU - Carr, Magda
N1 - Funding information: This work was supported by the Natural Environment Research Council (NERC)-funded ONE Planet Doctoral Training Partnership (Samuel George Hartharn-Evans, grant no. NE/S007512/1) and a Turing Global Fellowship (Samuel George Hartharn-Evans). Partial funding for travel was provided by the Natural Science and Engineering Research Council of Canada RGPIN-311844-37157.
PY - 2024/1/30
Y1 - 2024/1/30
N2 - While well-established energy-based methods of quantifying diapycnal mixing in process-study numerical models are often used to provide information about when mixing occurs, and how much mixing has occurred, describing how and where this mixing has taken place remains a challenge. Moreover, methods based on sorting the density field struggle when the model is under-resolved and when there is uncertainty as to the definition of the reference density when bathymetry is present. Here, an alternative method of understanding mixing is proposed. Paired histograms of user-selected variables (which we abbreviate USPs (user-controlled scatter plots)) are employed to identify mixing fluid and are then used to display regions of fluid in physical space that are undergoing mixing. This paper presents two case studies showcasing this method: shoaling internal solitary waves and a shear instability in cold water influenced by the nonlinearity of the equation of state. For the first case, the USP method identifies differences in the mixing processes associated with different internal solitary wave breaking types, including differences in the horizontal extent and advection of mixed fluid. For the second case, the method is used to identify how density and passive tracers are mixed within the core of the asymmetric cold-water Kelvin–Helmholtz instability.
AB - While well-established energy-based methods of quantifying diapycnal mixing in process-study numerical models are often used to provide information about when mixing occurs, and how much mixing has occurred, describing how and where this mixing has taken place remains a challenge. Moreover, methods based on sorting the density field struggle when the model is under-resolved and when there is uncertainty as to the definition of the reference density when bathymetry is present. Here, an alternative method of understanding mixing is proposed. Paired histograms of user-selected variables (which we abbreviate USPs (user-controlled scatter plots)) are employed to identify mixing fluid and are then used to display regions of fluid in physical space that are undergoing mixing. This paper presents two case studies showcasing this method: shoaling internal solitary waves and a shear instability in cold water influenced by the nonlinearity of the equation of state. For the first case, the USP method identifies differences in the mixing processes associated with different internal solitary wave breaking types, including differences in the horizontal extent and advection of mixed fluid. For the second case, the method is used to identify how density and passive tracers are mixed within the core of the asymmetric cold-water Kelvin–Helmholtz instability.
UR - http://www.scopus.com/inward/record.url?scp=85184064869&partnerID=8YFLogxK
U2 - 10.5194/npg-31-61-2024
DO - 10.5194/npg-31-61-2024
M3 - Article
SN - 1023-5809
VL - 31
SP - 61
EP - 74
JO - Nonlinear Processes in Geophysics
JF - Nonlinear Processes in Geophysics
IS - 1
ER -