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Mechanisms of Cell Motion in Confined Geometries

R. J. Hawkins, R. Voituriez (2010)

Mathematical Modelling of Natural Phenomena

We present a simple mechanism of cell motility in a confined geometry, inspired by recent motility assays in microfabricated channels. This mechanism relies mainly on the coupling of actin polymerisation at the cell membrane to geometric confinement. We first show analytically using a minimal model of polymerising viscoelastic gel confined in a narrow channel that spontaneous motion occurs due to polymerisation alone. Interestingly, this mechanism...

Numerical methods for fourth order nonlinear degenerate diffusion problems

Jürgen Becker, Günther Grün, Martin Lenz, Martin Rumpf (2002)

Applications of Mathematics

Numerical schemes are presented for a class of fourth order diffusion problems. These problems arise in lubrication theory for thin films of viscous fluids on surfaces. The equations being in general fourth order degenerate parabolic, additional singular terms of second order may occur to model effects of gravity, molecular interactions or thermocapillarity. Furthermore, we incorporate nonlinear surface tension terms. Finally, in the case of a thin film flow driven by a surface active agent (surfactant),...

Numerical simulation of gluey particles

Aline Lefebvre (2009)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

We propose here a model and a numerical scheme to compute the motion of rigid particles interacting through the lubrication force. In the case of a particle approaching a plane, we propose an algorithm and prove its convergence towards the solutions to the gluey particle model described in [B. Maury, ESAIM: Proceedings 18 (2007) 133–142]. We propose a multi-particle version of this gluey model which is based on the projection of the velocities onto a set of admissible velocities. Then, we describe...

Numerical simulation of gluey particles

Aline Lefebvre (2008)

ESAIM: Mathematical Modelling and Numerical Analysis

We propose here a model and a numerical scheme to compute the motion of rigid particles interacting through the lubrication force. In the case of a particle approaching a plane, we propose an algorithm and prove its convergence towards the solutions to the gluey particle model described in [B. Maury, ESAIM: Proceedings18 (2007) 133–142]. We propose a multi-particle version of this gluey model which is based on the projection of the velocities onto a set of admissible velocities. Then, we describe...

Numerical solution of a 1-d elastohydrodynamic problem in magnetic storage devices

Iñigo Arregui, José Jesús Cendán, Carlos Parés, Carlos Vázquez (2008)

ESAIM: Mathematical Modelling and Numerical Analysis

In this work we present new numerical methods to simulate the mechanics of head-tape magnetic storage devices. The elastohydrodynamic problem is formulated in terms of a coupled system which is governed by a nonlinear compressible Reynolds equation for the air pressure over the head, and a rod model for the tape displacement. A fixed point algorithm between the solutions of the elastic and hydrodynamic problems is proposed. For the nonlinear Reynolds equation, a characteristics method and a...

On the existence of pullback attractor for a two-dimensional shear flow with Tresca's boundary condition

Mahdi Boukrouche, Grzegorz Łukaszewicz (2008)

Banach Center Publications

We consider a two-dimensional Navier-Stokes shear flow with time dependent boundary driving and subject to Tresca law. We establish the existence of a unique global in time solution and then, using a recent method based on the concept of the Kuratowski measure of noncompactness of a bounded set, we prove the existence of the pullback attractor for the associated cocycle. This research is motivated by a problem from lubrication theory.

On the optimal control of coefficients in elliptic problems. Application to the optimization of the head slider

Ionel Ciuperca, Mohamed El Alaoui Talibi, Mohammed Jai (2005)

ESAIM: Control, Optimisation and Calculus of Variations

We consider an optimal control problem for a class of non-linear elliptic equations. A result of existence and uniqueness of the state equation is proven under weaker hypotheses than in the literature. We also prove the existence of an optimal control. Applications to some lubrication problems and numerical results are given.

On the optimal control of coefficients in elliptic problems. Application to the optimization of the head slider

Ionel Ciuperca, Mohamed El Alaoui Talibi, Mohammed Jai (2010)

ESAIM: Control, Optimisation and Calculus of Variations

We consider an optimal control problem for a class of non-linear elliptic equations. A result of existence and uniqueness of the state equation is proven under weaker hypotheses than in the literature. We also prove the existence of an optimal control. Applications to some lubrication problems and numerical results are given.

Qualitative properties of the free-boundary of the Reynolds equation in lubrication.

S. J. Alvarez (1989)

Publicacions Matemàtiques

The hydrodynamic lubrication of a cylindrical bearing is governed by the Reynolds equation that must be satisfied by the pressure of lubricating oil. When cavitation occurrs we are carried to an elliptic free-boundary problem where the free-boundary separates the lubricated region from the cavited region.Some qualitative properties are obtained about the shape of the free-boundary as well as the localization of the cavited region.

Shear-induced Electrokinetic Lift at Large Péclet Numbers

O. Schnitzer, I. Frankel, E. Yariv (2012)

Mathematical Modelling of Natural Phenomena

We analyze the problem of shear-induced electrokinetic lift on a particle freely suspended near a solid wall, subject to a homogeneous (simple) shear. To this end, we apply the large-Péclet-number generic scheme recently developed by Yariv et al. (J. Fluid Mech., Vol. 685, 2011, p. 306). For a force- and torque-free particle, the driving flow comprises three components, respectively describing (i) a particle translating parallel to the wall; (ii) a particle rotating with an angular velocity vector...

The Effect of Crystal-Melt Surface Energy on the Stability of Ultra-Thin Melt Films

M. Beerman, L. N. Brush (2008)

Mathematical Modelling of Natural Phenomena

The stability and evolution of very thin, single component, metallic-melt films is studied by analysis of coupled strongly nonlinear equations for gas-melt (GM) and crystal-melt (CM) interfaces, derived using the lubrication approximation. The crystal-melt interface is deformable by freezing and melting, and there is a thermal gradient applied across the film. Linear analysis reveals that there is a maximum applied far-field temperature in the gas, beyond which there is no film instability. Instabilities...

Two-Layer Flow with One Viscous Layer in Inclined Channels

O. K. Matar, G. M. Sisoev, C. J. Lawrence (2008)

Mathematical Modelling of Natural Phenomena

We study pressure-driven, two-layer flow in inclined channels with high density and viscosity contrasts. We use a combination of asymptotic reduction, boundary-layer theory and the Karman-Polhausen approximation to derive evolution equations that describe the interfacial dynamics. Two distinguished limits are considered: where the viscosity ratio is small with density ratios of order unity, and where both density and viscosity ratios are small. The evolution equations account for the presence of...

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