Search results for "hydrodynamic"
showing 10 items of 530 documents
Matter Mixing in Aspherical Core-collapse Supernovae: Three-dimensional Simulations with Single Star and Binary Merger Progenitor Models for SN 1987A
2019
We perform three-dimensional hydrodynamic simulations of aspherical core-collapse supernovae focusing on the matter mixing in SN 1987A. The impacts of four progenitor (pre-supernova) models and parameterized aspherical explosions are investigated. The four pre-supernova models include a blue supergiant (BSG) model based on a slow merger scenario developed recently for the progenitor of SN 1987A (Urushibata et al. 2018). The others are a BSG model based on a single star evolution and two red supergiant (RSG) models. Among the investigated explosion (simulation) models, a model with the binary merger progenitor model and with an asymmetric bipolar-like explosion, which invokes a jetlike explo…
Gravitational wave signature of proto-neutron star convection: I. MHD numerical simulations
2021
Gravitational waves provide a unique and powerful opportunity to constrain the dynamics in the interior of proto-neutron stars during core collapse supernovae. Convective motions play an important role in generating neutron stars magnetic fields, which could explain magnetar formation in the presence of fast rotation. We compute the gravitational wave emission from proto-neutron star convection and its associated dynamo, by post-processing three-dimensional MHD simulations of a model restricted to the convective zone in the anelastic approximation. We consider two different proto-neutron star structures representative of early times (with a convective layer) and late times (when the star is…
Modelling circulation in an ice-covered lake
2010
In deep ice-covered lakes with temperatures below 4 °C the heat flux from the bottom sediment results in a horizontal density gradient and a consequent flow along the bottom slope. Measurements in Lake Paajarvi, Finland, show a stable temperature field where a heat gain through the bottom and a heat loss through the ice nearly balance each other. The circulation is thermal with low velocities (less than 1.5 cm s -1 ). We used the 3D hydrodynamic Princeton Ocean Model as a tool to simulate the water circulation and the temperature distribution under the ice. The model forcing was based on field temperature measurements. The model simulations suggest that in midwinter the velocity field of th…
A multidisciplinary analytical framework to delineate spawning areas and quantify larval dispersal in coastal fish
2019
International audience; Assessing larval dispersal is essential to understand the structure and dynamics of marine populations. However, knowledge about early-life dispersal is sparse, and so is our understanding of the spawning process, perhaps the most obscure component of biphasic life cycles. Indeed, the poorly known species-specific spawning modality and early-life traits, along with the high spatio-temporal variability of the oceanic circulation experienced during larval drift, hamper our ability to properly appraise the realized connectivity of coastal fishes. Here, we propose an analytical framework which combines Lagrangian modeling, network theory, otolith analyses and biogeograph…
Fish functional traits are affected by hydrodynamics at small spatial scale
2016
The Mediterranean damselfish Chromis chromis is a species with a broad distribution found both in the Mediterranean Sea and Eastern Atlantic as far south as the coast of Angola. We hypothesized that the species may have significant functional morphological plasticity to adapt along a gradient of environmental conditions. It is a non-migratory zooplanktivorous species and spends the daytime searching for food in the middle of the water column. Therefore, local hydrodynamics could be one of the environmental factors affecting traits of C. chromis with repercussions at the population level. We compared the body condition, individual growth and body shapes of damselfish collected under two diff…
The role of noise on the steady state distributions of phytoplankton populations
2016
The spatio-temporal behaviour of total chlorophyll concentration is investigated in the middle of the Tyrrhenian Sea by using a stochastic approach. The study is based on a reaction-diffusion-taxis model, which is used to analyse the dynamics of five phytoplankton groups, responsible for about 80% of the total chlorophyll a inside the euphotic zone of the water column. The analysis is performed by considering: (i) the intraspecific competition of the phytoplanktonic groups for limiting factors, i.e. light intensity and nutrient concentration, (ii) the seasonal changes of environmental variables, and (iii) the random fluctuations of the components of the velocity field and temperature. Speci…
High-resolution numerical modelling of the barotropic tides in the Gulf of Gabes, eastern Mediterranean Sea (Tunisia)
2017
International audience; A high-resolution 2D barotropic tidal model was developed for the Gulf of Gabes and used to characterise hydrodynamic processes and tidal dynamics. The model is based on the Regional Ocean Modelling System. It is forced at the open boundaries by the semidiurnal M2 and S2 astronomical components while meteorological forcing has been neglected. The model results show good agreement with observations confirming that it reproduces the gulf's main tidal characteristics reasonably well. In fact, the simulated semidiurnal tidal components M2 and S2 generate important sea level variations and coastal currents. Tidal propagation is directed to the gulf's western sector while …
Spatiotemporal Dispersal and Deposition of Fish Farm Wastes: A Model Study from Central Norway
2017
Abstract A spatially explicit coupled hydrodynamic-mass transport model system was used to simulate dispersal of particulate organic matter from Atlantic salmon (Salmo salar) farming in central Norway. Model setups of 32 m horizontal resolution were run for periods of up to 650 days for 3 sites of different oceanographic characteristics: one fjord location, one medium-exposed location influenced by fjord water and one coastal location. Records on feed used for each cage at each location were converted to feces released based on a published mass balance model. The results from the simulations were compared with scores from corresponding mandatory benthic surveys (MOM-B) of the sediment layer…
Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy
2019
Depending on their reproductive strategy, different fish species aim to aggregate or disperse eggs and larvae in their reproductive habitat. Many pelagic species disperse their eggs widely around the potential nursery areas. Larval dispersion or aggregation affects population sub‐structuring, which has important implications in fisheries management and conservation of the natural spatial diversity in populations. The dispersion of larval vendace (Coregonus albula) was quantified in two oligotrophic Finnish lakes, and effects of density and environmental variables on the inter‐annual variation in the larval distribution were examined by analysing spatial abundance data from the lakes from 19…
Hydrodynamic IL10 Gene Transfer in Human Colon: Results from an "EX VIVO" Study with Potential Clinical Application in Crohn's Disease.
2017
Background: The aim of this work is to evaluate the efficacy of hydrodynamic venous IL10 gene delivery to "ex vivo" human colon segments and to determine its potential interest in Crohn's disease treatment. Methods: Twenty human colon segments were obtained from surgical resections. Hydrodynamic transfection through the main vein of the pedicle with 50 mL of hIL10 plasmid (20 mu g/mL) solution was performed on 13 of them. Tissue sections were cultured and DNA, RNA, and protein copies were determined after 1, 2, and 4 days. Data obtained were compared with 6 nontransfected specimens. Finally, 1 specimen was injected with gold nanoparticles, and their distribution was examined under electron …