Experimental and numerical investigation of density current over macro-roughness

Y. Jiang, Xiaofeng Liu

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The dynamics of density current over a bottom covered by macro-roughness elements were investigated by laboratory experiments and a computational model using large eddy simulations. The macro-roughness considered had significant size in comparison with the scale of density current. Five different roughness conditions were considered, namely flat bottom (for reference), half spheres, fine gravels, medium gravels, and large gravels. These bottom conditions had variations in roughness element size, shape, angularity, and spatial configuration. The density current was a lock-exchange type with a density difference of 1% between the two fluids initially separated by a gate in the middle. In the computational model, the roughness was captured using two different methods depending on the size of the roughness elements. For the large roughness elements, i.e., the half spheres and the medium and large gravels, an immersed boundary method was used to resolve the surface of each gravel, which was obtained through 3D laser scanning. The realistic and physically correct placement of these scanned objects in the simulation domain was achieved using a computer tool which can detect the collision of rigid bodies and simulate their dynamics. For the fine gravels, a rough wall function was used. The computational model was validated with the data measured in the experiments, including front position and velocity, and point velocity measurement within the current. The results show that density currents over macro-roughness have distinct behavior from those over a smooth boundary. The characteristics (size, angularity, and pavement pattern) of the macro-roughness play a key role in the current development. Macro-roughness significantly retards the front propagation and enhances entrainment.

Original languageEnglish (US)
Pages (from-to)97-116
Number of pages20
JournalEnvironmental Fluid Mechanics
Volume18
Issue number1
DOIs
StatePublished - Feb 1 2018

Fingerprint

density current
roughness
Macros
Current density
Surface roughness
Gravel
gravel
Wall function
large eddy simulation
Large eddy simulation
pavement
Pavements
Velocity measurement
entrainment
collision
laser
Experiments
Scanning
Fluids
fluid

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Water Science and Technology

Cite this

@article{1aded8b532384b128b7e3cc47214d6e1,
title = "Experimental and numerical investigation of density current over macro-roughness",
abstract = "The dynamics of density current over a bottom covered by macro-roughness elements were investigated by laboratory experiments and a computational model using large eddy simulations. The macro-roughness considered had significant size in comparison with the scale of density current. Five different roughness conditions were considered, namely flat bottom (for reference), half spheres, fine gravels, medium gravels, and large gravels. These bottom conditions had variations in roughness element size, shape, angularity, and spatial configuration. The density current was a lock-exchange type with a density difference of 1{\%} between the two fluids initially separated by a gate in the middle. In the computational model, the roughness was captured using two different methods depending on the size of the roughness elements. For the large roughness elements, i.e., the half spheres and the medium and large gravels, an immersed boundary method was used to resolve the surface of each gravel, which was obtained through 3D laser scanning. The realistic and physically correct placement of these scanned objects in the simulation domain was achieved using a computer tool which can detect the collision of rigid bodies and simulate their dynamics. For the fine gravels, a rough wall function was used. The computational model was validated with the data measured in the experiments, including front position and velocity, and point velocity measurement within the current. The results show that density currents over macro-roughness have distinct behavior from those over a smooth boundary. The characteristics (size, angularity, and pavement pattern) of the macro-roughness play a key role in the current development. Macro-roughness significantly retards the front propagation and enhances entrainment.",
author = "Y. Jiang and Xiaofeng Liu",
year = "2018",
month = "2",
day = "1",
doi = "10.1007/s10652-016-9500-1",
language = "English (US)",
volume = "18",
pages = "97--116",
journal = "Environmental Fluid Mechanics",
issn = "1567-7419",
publisher = "Springer Netherlands",
number = "1",

}

Experimental and numerical investigation of density current over macro-roughness. / Jiang, Y.; Liu, Xiaofeng.

In: Environmental Fluid Mechanics, Vol. 18, No. 1, 01.02.2018, p. 97-116.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Experimental and numerical investigation of density current over macro-roughness

AU - Jiang, Y.

AU - Liu, Xiaofeng

PY - 2018/2/1

Y1 - 2018/2/1

N2 - The dynamics of density current over a bottom covered by macro-roughness elements were investigated by laboratory experiments and a computational model using large eddy simulations. The macro-roughness considered had significant size in comparison with the scale of density current. Five different roughness conditions were considered, namely flat bottom (for reference), half spheres, fine gravels, medium gravels, and large gravels. These bottom conditions had variations in roughness element size, shape, angularity, and spatial configuration. The density current was a lock-exchange type with a density difference of 1% between the two fluids initially separated by a gate in the middle. In the computational model, the roughness was captured using two different methods depending on the size of the roughness elements. For the large roughness elements, i.e., the half spheres and the medium and large gravels, an immersed boundary method was used to resolve the surface of each gravel, which was obtained through 3D laser scanning. The realistic and physically correct placement of these scanned objects in the simulation domain was achieved using a computer tool which can detect the collision of rigid bodies and simulate their dynamics. For the fine gravels, a rough wall function was used. The computational model was validated with the data measured in the experiments, including front position and velocity, and point velocity measurement within the current. The results show that density currents over macro-roughness have distinct behavior from those over a smooth boundary. The characteristics (size, angularity, and pavement pattern) of the macro-roughness play a key role in the current development. Macro-roughness significantly retards the front propagation and enhances entrainment.

AB - The dynamics of density current over a bottom covered by macro-roughness elements were investigated by laboratory experiments and a computational model using large eddy simulations. The macro-roughness considered had significant size in comparison with the scale of density current. Five different roughness conditions were considered, namely flat bottom (for reference), half spheres, fine gravels, medium gravels, and large gravels. These bottom conditions had variations in roughness element size, shape, angularity, and spatial configuration. The density current was a lock-exchange type with a density difference of 1% between the two fluids initially separated by a gate in the middle. In the computational model, the roughness was captured using two different methods depending on the size of the roughness elements. For the large roughness elements, i.e., the half spheres and the medium and large gravels, an immersed boundary method was used to resolve the surface of each gravel, which was obtained through 3D laser scanning. The realistic and physically correct placement of these scanned objects in the simulation domain was achieved using a computer tool which can detect the collision of rigid bodies and simulate their dynamics. For the fine gravels, a rough wall function was used. The computational model was validated with the data measured in the experiments, including front position and velocity, and point velocity measurement within the current. The results show that density currents over macro-roughness have distinct behavior from those over a smooth boundary. The characteristics (size, angularity, and pavement pattern) of the macro-roughness play a key role in the current development. Macro-roughness significantly retards the front propagation and enhances entrainment.

UR - http://www.scopus.com/inward/record.url?scp=85006961607&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85006961607&partnerID=8YFLogxK

U2 - 10.1007/s10652-016-9500-1

DO - 10.1007/s10652-016-9500-1

M3 - Article

AN - SCOPUS:85006961607

VL - 18

SP - 97

EP - 116

JO - Environmental Fluid Mechanics

JF - Environmental Fluid Mechanics

SN - 1567-7419

IS - 1

ER -