Analysis of one-dimensional models for exchange flows under strong stratification

Steven Kaptein, K.J. van de Wal, Leon Kamp, Vincenzo Armenio, Herman Clercx, Matias Duran Matute (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here, we propose two new parametrizations of the horizontal density gradient leading to one-dimensional models able to tackle strongly stratified exchange flows at high and low Schmidt number values. The models are extensively tested against results from laminar two-dimensional simulations and are shown to outperform the models using the classical constant parametrization for the horizontal density gradients. Four different flow regimes are found by exploring the parameter space defined by the gravitational Reynolds number Re g, the Schmidt number Sc, and the aspect ratio of the channel Γ. For small values of Re gΓ, when diffusion dominates, all models perform well. However, as Re gΓ increases, two clearly distinct regimes emerge depending on the Sc value, with an equally clear distinction of the performance of the one-dimensional models.

Original languageEnglish
Pages (from-to)41-56
Number of pages16
JournalOcean Dynamics
Volume70
Issue number1
DOIs
Publication statusPublished - 1 Jan 2020

Fingerprint

stratification
turbulent mixing
analysis
Reynolds number
simulation

Keywords

  • Density stratification
  • Estuarine circulation
  • Exchange flow
  • One-dimensional water column models

Cite this

@article{21c9e719972848ac8c2ca9c0a76133e8,
title = "Analysis of one-dimensional models for exchange flows under strong stratification",
abstract = "One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here, we propose two new parametrizations of the horizontal density gradient leading to one-dimensional models able to tackle strongly stratified exchange flows at high and low Schmidt number values. The models are extensively tested against results from laminar two-dimensional simulations and are shown to outperform the models using the classical constant parametrization for the horizontal density gradients. Four different flow regimes are found by exploring the parameter space defined by the gravitational Reynolds number Re g, the Schmidt number Sc, and the aspect ratio of the channel Γ. For small values of Re gΓ, when diffusion dominates, all models perform well. However, as Re gΓ increases, two clearly distinct regimes emerge depending on the Sc value, with an equally clear distinction of the performance of the one-dimensional models.",
keywords = "Density stratification, Estuarine circulation, Exchange flow, One-dimensional water column models",
author = "Steven Kaptein and {van de Wal}, K.J. and Leon Kamp and Vincenzo Armenio and Herman Clercx and {Duran Matute}, Matias",
year = "2020",
month = "1",
day = "1",
doi = "10.1007/s10236-019-01320-z",
language = "English",
volume = "70",
pages = "41--56",
journal = "Ocean Dynamics",
issn = "1616-7341",
publisher = "Springer",
number = "1",

}

Analysis of one-dimensional models for exchange flows under strong stratification. / Kaptein, Steven; van de Wal, K.J.; Kamp, Leon; Armenio, Vincenzo; Clercx, Herman; Duran Matute, Matias (Corresponding author).

In: Ocean Dynamics, Vol. 70, No. 1, 01.01.2020, p. 41-56.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Analysis of one-dimensional models for exchange flows under strong stratification

AU - Kaptein, Steven

AU - van de Wal, K.J.

AU - Kamp, Leon

AU - Armenio, Vincenzo

AU - Clercx, Herman

AU - Duran Matute, Matias

PY - 2020/1/1

Y1 - 2020/1/1

N2 - One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here, we propose two new parametrizations of the horizontal density gradient leading to one-dimensional models able to tackle strongly stratified exchange flows at high and low Schmidt number values. The models are extensively tested against results from laminar two-dimensional simulations and are shown to outperform the models using the classical constant parametrization for the horizontal density gradients. Four different flow regimes are found by exploring the parameter space defined by the gravitational Reynolds number Re g, the Schmidt number Sc, and the aspect ratio of the channel Γ. For small values of Re gΓ, when diffusion dominates, all models perform well. However, as Re gΓ increases, two clearly distinct regimes emerge depending on the Sc value, with an equally clear distinction of the performance of the one-dimensional models.

AB - One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here, we propose two new parametrizations of the horizontal density gradient leading to one-dimensional models able to tackle strongly stratified exchange flows at high and low Schmidt number values. The models are extensively tested against results from laminar two-dimensional simulations and are shown to outperform the models using the classical constant parametrization for the horizontal density gradients. Four different flow regimes are found by exploring the parameter space defined by the gravitational Reynolds number Re g, the Schmidt number Sc, and the aspect ratio of the channel Γ. For small values of Re gΓ, when diffusion dominates, all models perform well. However, as Re gΓ increases, two clearly distinct regimes emerge depending on the Sc value, with an equally clear distinction of the performance of the one-dimensional models.

KW - Density stratification

KW - Estuarine circulation

KW - Exchange flow

KW - One-dimensional water column models

UR - http://www.scopus.com/inward/record.url?scp=85075935633&partnerID=8YFLogxK

U2 - 10.1007/s10236-019-01320-z

DO - 10.1007/s10236-019-01320-z

M3 - Article

VL - 70

SP - 41

EP - 56

JO - Ocean Dynamics

JF - Ocean Dynamics

SN - 1616-7341

IS - 1

ER -