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Cultivating oleaginous microalgae in specific culturing devices such as raceways is seen as a future way to produce biofuel. The complexity of this process coupling non linear biological activity to hydrodynamics makes the optimization problem very delicate. The large amount of parameters to be taken into account paves the way for a useful mathematical modeling. Due to the heterogeneity of raceways along the depth dimension regarding temperature, light intensity or nutrients availability, we adopt...
We propose a quasi-Newton algorithm for solving fluid-structure interaction problems. The basic idea of the method is to build an approximate tangent operator which is cost effective and which takes into account the so-called added mass effect. Various test cases show that the method allows a significant reduction of the computational effort compared to relaxed fixed point algorithms. We present 2D and 3D fluid-structure simulations performed either with a simple 1D structure model or with shells...
We propose a quasi-Newton algorithm for solving
fluid-structure interaction problems. The basic idea of the method is
to build an approximate tangent operator which is cost effective and
which takes into account the so-called added mass effect.
Various test cases show that the method allows a significant reduction
of the computational effort compared to relaxed fixed point
algorithms. We present 2D and 3D fluid-structure simulations performed
either with a simple 1D structure model or with...
This paper provides new results of consistence and convergence of the lumped parameters (ODE models) toward one-dimensional (hyperbolic or parabolic) models for blood flow. Indeed, lumped parameter models (exploiting the electric circuit analogy for the circulatory system) are shown to discretize continuous 1D models at first order in space. We derive the complete set of equations useful for the blood flow networks, new schemes for electric circuit analogy, the stability criteria that guarantee...
This paper provides new results of consistence and convergence of the
lumped parameters (ODE models) toward one-dimensional (hyperbolic or parabolic) models for blood flow. Indeed,
lumped parameter models (exploiting the electric circuit analogy for the circulatory system)
are shown to discretize continuous 1D models
at first order in space.
We derive the complete set of equations useful for the blood flow networks,
new schemes for electric circuit analogy,
the stability criteria that...
This work aims to extend in two distinct directions results recently obtained in [10]. In a first step we focus on the possible extension of our results to the time
dependent case. Whereas in the second part some preliminary numerical simulations aim to
give orders of magnitudes in terms of numerical costs of direct 3D simulations. We consider, in the first part, the time dependent rough problem for a simplified heat
equation in a straight channel that mimics the axial...
We present the fiber-spring elastic model of the arterial wall with atherosclerotic
plaque composed of a lipid pool and a fibrous cap. This model allows us to reproduce
pressure to cross-sectional area relationship along the diseased vessel which is used in
the network model of global blood circulation. Atherosclerosis attacks a region of
systemic arterial network. Our approach allows us to examine the impact of the diseased
region onto global haemodynamics....
In this work, we are interested in two different diffusion models for multicomponent
mixtures. We numerically recover experimental results underlining the inadequacy of the
usual Fick diffusion model, and the importance of using the Maxwell-Stefan model in
various situations. This model nonlinearly couples the mole fractions and the fluxes of
each component of the mixture. We then consider a subregion of the lower part of the lung,
in which we compare...
Our purpose is to estimate numerically the influence of particles on the global viscosity of fluid–particle mixtures. Particles are supposed to rigid, and the surrounding fluid is newtonian. The motion of the mixture is computed directly, i.e. all the particle motions are computed explicitly. Apparent viscosity, based on the force exerted by the fluid on the sliding walls, is computed at each time step of the simulation. In order to perform long–time simulations and still control the solid fraction,...
Our purpose is to estimate numerically the influence of particles on the global viscosity of fluid–particle mixtures. Particles are supposed to rigid, and the surrounding fluid is newtonian. The motion of the mixture is computed directly, i.e. all the particle motions are computed explicitly.
Apparent viscosity, based on the force exerted by the fluid on the sliding walls, is computed at each time step of the simulation.
In order to perform long–time simulations and still control the solid fraction,...
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