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[en] NUMERICAL IMPLEMENTATION OF ACOPPLING SURFACE WATER: GROUNDWATER / [pt] UMA IMPLEMENTAÇÃO NUMÉRICA DO ACOPLAMENTO ÁGUA SUPERFICIAL: ÁGUA SUBTERRÂNEAJOAO PAULO CASTAGNOLI 14 December 2007 (has links)
[pt] A relação entre os processos hidrológicos de escoamento
superficial e
subterrâneo apresenta uma grande variabilidade espacial
e
temporal. Podendo
ser representado de forma qualitativa como parte
sequêncial do ciclo
hidrológico, estes processos, demostram sua grande
dependência e
importância nos estudos de balanços hídricos. Visando
uma
representação
quantitativa, este trabalho faz o acoplamento, entre os
modelos numéricos de
escoamento superficial e de fluxo em meios porosos. Para
o
meio poroso
adotou-se o modelo numérico SWMS_3D (Simunek et al,
1995),
o qual resolve
a equação de Richards, para fluxo em meios porosos
saturados e não
saturados nas três dimensões. Na simulação da dinâmica
superficial, foram
desenvolvidos dois modelos derivados das equações de
Saint-
Venant: o
modelo da Onda Cinemática e o modelo de Difusão. Para a
solução numérica
foi empregado o método dos elementos finitos através da
formulaçao de
Galerkin, adotando uma malha tridimensional de elementos
tetraédricos,
formando uma sub-malha de elementos triangulares na
superfície. O modelo
de escoamento superficial emprega a malha triangular e
interage com o
programa SWMS_3D modificado (que utiliza a malha de
tetraédros) através
das imposições das condições de contorno transientes.
Este, responderá com
uma parcela de fluxo correspondente à recarga ou
descarga
no contorno a
cada passo de tempo. Com isso, o modelo gerado é capaz
de
quantificar
espacialmente e temporalmente as cargas de pressão em
todos os pontos do
domínio de estudo. / [en] While analyzing the interaction between the hydrological
processes of
surface and groundwater flow, it is seen that there is a
big difference in its
interaction in the space and time. These processes can be
represented in a
qualitative form as part of the hydrological cycle,
demonstrating its
dependences and importance in the hydrological balance.
This work does the
numerical coupling of the surface and groundwater flow.
This work adopted the
SWMS_3D numerical model (Simunek et. al., 1995), which
resolves the
Richards equation for saturated and non saturated porous
media flow in 3D. In
order to simulate the superficial dynamic flow, two models
from Saint-Vennat
equation were developed, these models are: the cinematic
wave model and the
diffusion model. These two models consider the average
outflow in sections in a
2D scenario. For the numerical solution the finite element
method was adopted
through the Galerkin formulation. Adopting a 3D domain
mesh of tetrahedral
elements, seen from above, in 2D, we can see a triangular
element mesh. The
superficial flow model uses the triangular mesh and
iterates with the SWMS_3D
modified software, which uses the tetrahedral elements
mesh. This was done
by changes in the boundary conditions to the models. The
SWMS_3D will
answer with a flow portion corresponding to a sink or
source action in the
surface, in each time step. Finally the generated model is
able to quantify in
space and in time the pressure head in the study domain.
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Sur la compréhension des phénomènes de couplage fluide-structure dans les propulseurs de fuséeDevesvre, Julie 13 December 2011 (has links)
Dans les propulseurs de fusée, des instabilités aéroacoustiques et des interactions de type fluide-structure sont à l'origine de fortes oscillations de poussées pouvant déranger la poussée du moteur mais également causer des dommages non négligeables. On trouve dans les moteurs de fusée des protections thermiques de face (PTF) coincées entre les pains de propergol. Leurs déplacements se trouvent être la principale cause des interactions fluide structure (IFS) présentes dans les booster. Dans ce contexte, nous avons développé une approche numérique visant à simuler les problèmes d'IFS. Notre méthode se base sur le couplage de deux codes dissociés : l'écoulement est simulé avec CARBUR tandis que la dynamique des structures déformables est traitée par MARCUS. Une loi de comportement hyperélastique a été implémentée dans CARBUR afin de simuler le mouvement des PTF. Une campagne expérimentale a été menée dans notre laboratoire sur le tube à chocs T80 et en guide de validation du couplage des codes, les résultats numériques et expérimentaux ont été confrontés. / In a solid rocket motor, high pressure oscillations induced by aeroacoustic instabilities and fluid structure interaction (FSI) may lead to disturb rocket thrust and cause damages. In the rocket motors, flexible inhibitors made of insulating material are initially bonded to the propellant, and FSI is mainly induced by their displacement. In this context, a numérical approach to simulate FSI problems has been developped. Our method is based on the coupling of two dissociated codes : fluid flow is computed with CARBUR, while the dynamics of deformable structures is simulated by MARCUS. A hyperelastic behaviour law has been implemented in MARCUS in order to simulate the movement of flexible inhibitors. An experimental approach has been leaded in the shock waves tubes (T80) in our laboratory and as a validation of FSI coupling codes, numerical and experimental results have been compared.
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