|
|
|
|
|
| Guizien, Katell; Orvain, Francis; Duchene, Jean-claude; Le Hir, Pierre. |
| The average bed shear stress and bed friction factor of samples with any roughness was derived from the head loss between upstream and downstream of a test section in an erosion tunnel. The method was validated in both hydraulically smooth (plexiglass; Reynolds number less than 25,000) and rough regimes (calibrated particles with known roughness). As a first step toward using this method on natural sediment, this method was tested with experimental mesocosms assembled from field collected materials (sieved sediments; diatoms). Bed shear stress measurement precision was high enough in the experiments to detect a positive significant relationship between bed friction factor and core roughness. The observed bed friction factor increase could be related to... |
| Tipo: Text |
Palavras-chave: Bed roughness; Friction factor; Mud beds; Biological activity; Erosion experiments. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00117/22807/20617.pdf |
| |
|
|
| Guizien, Katell. |
| Un modèle numérique de couche limite oscillante a été développé sur la base de la fermeture turbulente k-w transitionnelle de Wilcox (1992) permettant de décrire des couches limites transitionnelles et turbulentes (programme européen SEDMOC). En modifiant les constantes de diffusion et de transition du modèle de Wilcox et en introduisant une condition de décollement de couche limite sous l'effet d'un gradient de pression adverse, on a pu reproduire avec un bien meilleur accord que le modèle originel de Wilcox des simulations directes (Vittori et Verzicco, 1998) ainsi que les mesures de Jensen et al. (1989) d'écoulement oscillant sur fond plat lisse dans le régime turbulent intermittent (version 1DV, Guizien et al., 2003). Ce modèle décrit également mieux... |
| Tipo: Text |
|
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/00106/21686/19265.pdf |
| |
|
|
| Savelli, Raphael; Dupuy, Christine; Barille, Laurent; Lerouxel, Astrid; Guizien, Katell; Philippe, Anne; Bocher, Pierrick; Polsenaere, Pierre; Le Fouest, Vincent. |
| Microphytobenthos (MPB) from intertidal mudflats are key primary producers at the land–ocean interface. MPB can be more productive than phytoplankton and sustain both benthic and pelagic higher trophic levels. The objective of this study is to assess the contribution of light, mud temperature, and gastropod Peringia ulvae grazing pressure in shaping the seasonal MPB dynamics on the Brouage mudflat (NW France). We use a physical–biological coupled model applied to the sediment first centimetre for the year 2008. The simulated data compare to observations, including time-coincident remotely sensed and in situ data. The model suggests an MPB annual cycle characterised by a main spring bloom, a biomass depression in summer, and a moderate fall bloom. In early... |
| Tipo: Text |
|
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00471/58226/60732.pdf |
| |
|
|
| Dupuy, Christine; Mallet, Clarisse; Guizien, Katell; Montanie, Helene; Breret, Martine; Mornet, Francoise; Fontaine, Camille; Nerot, Caroline; Orvain, Francis. |
| Resuspension thresholds in terms of friction velocity were experimentally quantified for the prokaryotes, protists and for the first time, viruses of intertidal mudflat biofilms. Differences in resuspension thresholds could be related to the type, behaviour and size of microorganisms and their association with particles. Free microorganisms (viruses, bacteria and some nanoflagellates) were resuspended by weak flow at friction velocities lower than 2 cm s- 1. Chlorophyll a, some nanoflagellates and attached bacteria were resuspended together with the bed’s muddy sediment, which required friction velocities larger than 3 cm s- 1. Diatoms smaller than 60 μm were resuspended at velocities between 3 and 5 cm s- 1, while those larger than 60 μm were resuspended... |
| Tipo: Text |
Palavras-chave: Viruses; Microorganisms; Resuspension; Benthic-pelagic coupling; Spatial distribution; Mudflat. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00168/27922/26196.pdf |
| |
|
|
|
