Combined load in open channel: Modelling of transport layer at high bed shear

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F20%3A00347729" target="_blank" >RIV/68407700:21110/20:00347729 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1201/b22619" target="_blank" >http://dx.doi.org/10.1201/b22619</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1201/b22619" target="_blank" >10.1201/b22619</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Combined load in open channel: Modelling of transport layer at high bed shear

Popis výsledku v původním jazyce

Solid-liquid flows in geomorphological processes transport grains which are often supported by a combination of mutual collisions and turbulent suspension. The dominating support mecha-nism depends primarily on the size of transported sediment grains and on their local position within the internal structure of the sediment carrying flow. We focus on steady-state uniform turbulent open-channel flow in which some grains are suspended by turbulent eddies of carry-ing liquid and the rest is transported as (collisional) bed load. A modelling approach is dis-cussed which employs the flow internal structure (distributions of velocity and solids concen-tration) and quantifies a distribution of turbulent characteristics across the flow depth. This en-ables to evaluate at the local level the ability of the carrying liquid to support transported sedi-ment grains by the diffusive action of carrier turbulent eddies. The modelling results, obtained for flow conditions observed experimentally for lightweight sediment in our laboratory tilting flume, indicate that the widely used criterion for incipient turbulent suspension (the ratio of bed shear velocity and grain terminal settling velocity greater than 1.25) is appropriate. The chance for the local turbulent support (as additional mechanism to contact support) of grains appears to be more likely in the upper part of the transport layer developed in the flow above the mobile bed then in the lower part where intergranular contacts dominate. The part with turbulent sup-port of grains increases with the bed Shields parameter.

Název v anglickém jazyce

Combined load in open channel: Modelling of transport layer at high bed shear

Popis výsledku anglicky

Solid-liquid flows in geomorphological processes transport grains which are often supported by a combination of mutual collisions and turbulent suspension. The dominating support mecha-nism depends primarily on the size of transported sediment grains and on their local position within the internal structure of the sediment carrying flow. We focus on steady-state uniform turbulent open-channel flow in which some grains are suspended by turbulent eddies of carry-ing liquid and the rest is transported as (collisional) bed load. A modelling approach is dis-cussed which employs the flow internal structure (distributions of velocity and solids concen-tration) and quantifies a distribution of turbulent characteristics across the flow depth. This en-ables to evaluate at the local level the ability of the carrying liquid to support transported sedi-ment grains by the diffusive action of carrier turbulent eddies. The modelling results, obtained for flow conditions observed experimentally for lightweight sediment in our laboratory tilting flume, indicate that the widely used criterion for incipient turbulent suspension (the ratio of bed shear velocity and grain terminal settling velocity greater than 1.25) is appropriate. The chance for the local turbulent support (as additional mechanism to contact support) of grains appears to be more likely in the upper part of the transport layer developed in the flow above the mobile bed then in the lower part where intergranular contacts dominate. The part with turbulent sup-port of grains increases with the bed Shields parameter.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

20101 - Civil engineering

Projekt

<a href="/cs/project/GA19-18411S" target="_blank" >GA19-18411S: Modelování intenzivního chodu směsi dnových a nesených splavenin</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings of the 10th International Conference on Fluvial Hydraulics

ISBN

978-1-003-11095-8

ISSN

—

e-ISSN

—

Počet stran výsledku

8

Strana od-do

308-315

Název nakladatele

Taylor and Francis

Místo vydání

Abingdon

Místo konání akce

Delft

Datum konání akce

7. 7. 2020

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

—