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Displaying 1521 –
1540 of
3483
In this article, we propose an integrated model for oxygen transfer into the blood, coupled with a lumped mechanical model for the ventilation process. Objectives. We aim at investigating oxygen transfer into the blood at rest or exercise. The first task consists in describing nonlinear effects of the oxygen transfer under normal conditions. We also include the possible diffusion limitation in oxygen transfer observed in extreme regimes involving parameters such as alveolar and venous blood oxygen...
A pneumatic tyre in rotating motion with a constant angular velocity is assimilated to a torus whose generating circle has a radius . The contact of the tyre with the ground is schematized as an ellipse with semi-major axis . When and (where is the velocity of the sound), we show that at the rapid time scale , the air motion within a torus periodically excited on its surface generates an acoustic wave . A study of this acoustic wave is conducted and shows that the mode associated to...
In this paper we give a survey on modeling efforts concerning the CVRS. The material we
discuss is organized in accordance with modeling goals and stresses control and transport
issues. We also address basic modeling approaches and discuss some of the challenges for
mathematical modeling methodologies in the context of parameter estimation and model
validation.
A numerical model to compute the dynamics of glaciers is presented. Ice damage due to
cracks or crevasses can be taken into account whenever needed. This model allows
simulations of the past and future retreat of glaciers, the calving process or the
break-off of hanging glaciers. All these phenomena are strongly affected by climate
change.Ice is assumed to behave as an incompressible fluid with nonlinear viscosity, so that the
velocity and pressure...
In the present work we investigate the numerical simulation of liquid-vapor phase change
in compressible flows. Each phase is modeled as a compressible fluid equipped with its own
equation of state (EOS). We suppose that inter-phase equilibrium processes in the medium
operate at a short time-scale compared to the other physical phenomena such as convection
or thermal diffusion. This assumption provides an implicit definition of an equilibrium
EOS...
In the present work we investigate the numerical simulation of liquid-vapor phase change
in compressible flows. Each phase is modeled as a compressible fluid equipped with its own
equation of state (EOS). We suppose that inter-phase equilibrium processes in the medium
operate at a short time-scale compared to the other physical phenomena such as convection
or thermal diffusion. This assumption provides an implicit definition of an equilibrium
EOS...
We study the unsaturated flow of an incompressible liquid carrying a bacterial population through a porous medium contaminated with some pollutant. The biomass grows feeding on the pollutant and affecting at the same time all the physics of the flow. We formulate a mathematical model in a one-dimensional setting and we prove an existence theorem for it. The so-called fluid media scaling approach, often used in the literature, is discussed and its limitations are pointed out on the basis of a specific...
We present here a series of works which aims at describing geophysical flows in the equatorial zone, taking into account the dominating influence of the earth rotation. We actually proceed by successive approximations computing for each model the response of the fluid to the strong Coriolis penalisation. The main difficulty is due to the spatial variations of the Coriolis acceleration : in particular, as it vanishes at the equator, fast oscillations are trapped in a thin strip of latitudes.
Since cancer is a complex phenomenon that incorporates events occurring on different
length and time scales, therefore multiscale models are needed if we hope to adequately address
cancer specific questions. In this paper we present three different multiscale individual-cell-based
models, each motivated by cancer-related problems emerging from each of the spatial scales: extracellular,
cellular or subcellular, but also incorporating relevant information from other levels.
We apply these hybrid...
We present a model coupling the fire propagation equations in a bidimensional domain representing the surface, and the air movement equations in a three dimensional domain representing an air layer. As the air layer thickness is small compared with its length, an asymptotic analysis gives a three dimensional convective model governed by a bidimensional equation verified by a stream function. We also present the numerical simulations of these equations.
When two miscible fluids, such as glycerol (glycerin) and water, are brought in contact, they immediately diffuse in each other. However if the diffusion is sufficiently slow, large concentration gradients exist during some time. They can lead to the appearance of an “effective interfacial tension”. To study these phenomena we use the mathematical model consisting of the diffusion equation with convective terms and of the Navier-Stokes equations with the Korteweg stress. We prove the global existence...
When two miscible fluids, such as glycerol (glycerin) and water,
are brought in contact, they immediately diffuse in each other.
However if the diffusion is sufficiently slow, large concentration gradients exist
during some time. They can lead to the appearance of an
“effective interfacial tension”. To study these phenomena we
use the mathematical model
consisting of the diffusion equation with convective terms and of
the Navier-Stokes equations with the Korteweg stress.
We prove the global...
There are very few reference solutions in the literature on non-Boussinesq natural convection flows. We propose here a test case problem which extends the well-known De Vahl Davis differentially heated square cavity problem to the case of large temperature differences for which the Boussinesq approximation is no longer valid. The paper is split in two parts: in this first part, we propose as yet unpublished reference solutions for cases characterized by a non-dimensional temperature difference of...
Currently displaying 1521 –
1540 of
3483