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)

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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.

Originele taal-2Engels
Pagina's (van-tot)41-56
Aantal pagina's16
TijdschriftOcean Dynamics
Volume70
Nummer van het tijdschrift1
DOI's
StatusGepubliceerd - 1 jan 2020

Vingerafdruk

stratification
turbulent mixing
analysis
Reynolds number
simulation

Citeer dit

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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.",
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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, Nr. 1, 01.01.2020, blz. 41-56.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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AU - Duran Matute, Matias

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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.

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