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This paper describes a class of shape optimization problems for optical metamaterials comprised of periodic microscale inclusions composed of a dielectric, low-dimensional material suspended in a non-magnetic bulk dielectric. The shape…

Numerical Analysis · Mathematics 2024-01-08 Manaswinee Bezbaruah , Matthias Maier , Winnifried Wollner

We study nematic equilibria in an unbounded domain, with a two-dimensional regular polygonal hole with $K$ edges, in a reduced Landau-de Gennes framework. This complements our previous work on the "interior problem" for nematic equilibria…

Mathematical Physics · Physics 2022-10-05 Yucen Han , Apala Majumdar

We consider shape optimization problems subject to elliptic partial differential equations. In the context of the finite element method, the geometry to be optimized is represented by the computational mesh, and the optimization proceeds by…

Optimization and Control · Mathematics 2019-07-12 Tommy Etling , Roland Herzog , Estefanía Loayza , Gerd Wachsmuth

We propose an approach to a multiscale problem in the theory of thermotropic uniaxial nematics based on the method of statistical field theory. This approach enables us to relate the coefficients $A$, $B$, $C$, $L_1$ and $L_2$ of the…

Statistical Mechanics · Physics 2018-01-29 Bing-Sui Lu

Extensions of a previously presented Landau-de Gennes type liquid crystalline phase transition model for the direct isotropic/smectic-A (lamellar) a phase transition to the direct isotropic/smectic-C (tilted lamellar) transition are…

Soft Condensed Matter · Physics 2008-12-02 Nasser Mohieddin Abukhdeir , Alejandro D. Rey

This paper proposes a low order geometrically exact flexible beam formulation based on the utilisation of generic beam shape functions to approximate distributed kinematic properties of the deformed structure. The proposed nonlinear beam…

Classical Physics · Physics 2018-09-05 C. Howcroft , R. G. Cook , S. A. Neild , M. H. Lowenberg , J. E. Cooper , E. B. Coetzee

We consider surface finite elements and a semi-implicit time stepping scheme to simulate fluid deformable surfaces. Such surfaces are modeled by incompressible surface Navier-Stokes equations with bending forces. Here, we consider closed…

Numerical Analysis · Mathematics 2023-05-03 Veit Krause , Axel Voigt

A lattice Boltzmann scheme is presented which recovers the dynamics of nematic and chiral liquid crystals; the method essentially gives solutions to the Qian-Sheng equations for the evolution of the velocity and tensor order-parameter…

Soft Condensed Matter · Physics 2007-05-23 T. J. Spencer , C. M. Care

We investigate the solution landscape of a reduced Landau--de Gennes model for nematic liquid crystals on a two-dimensional hexagon at a fixed temperature, as a function of $\lambda$---the edge length. This is a generic example for reduced…

Mathematical Physics · Physics 2021-05-26 Yucen Han , Jianyuan Yin , Pingwen Zhang , Apala Majumdar , Lei Zhang

The problem of heterogeneous nucleation of second-phase in alloys in the vicinity of elastic defects is considered. The defect can be a dislocation line or a crack tip residing in a crystalline solid. We use the Ginzburg-Landau equation to…

Materials Science · Physics 2011-10-07 Christina Bjerkén , Ali R. Massih

Topological defects are ubiquitous on surfaces with orientational order fields. Here, we study equilibrium states generated by the feedback between geometry and nematic order on fluid membranes with an integer topological defect. When the…

Soft Condensed Matter · Physics 2024-11-14 D. J. G. Pearce , C. Thibault , Q. Chaboche , C. Blanch-Mercader

We consider the method of mappings for performing shape optimization for unsteady fluid-structure interaction (FSI) problems. In this work, we focus on the numerical implementation. We model the optimization problem such that it takes…

Optimization and Control · Mathematics 2024-06-21 Johannes Haubner , Michael Ulbrich

We study an optimization problem that aims to determine the shape of an obstacle that is submerged in a fluid governed by the Stokes equations. The mentioned flow takes place in a channel, which motivated the imposition of a Poiseuille-like…

Numerical Analysis · Mathematics 2021-08-13 John Sebastian H. Simon , Hirofumi Notsu

In shape optimisation it is desirable to obtain deformations of a given mesh without negative impact on the mesh quality. We propose a new algorithm using least square formulations of the Cauchy-Riemann equations. Our method allows to…

Optimization and Control · Mathematics 2021-06-09 José A. Iglesias , Kevin Sturm , Florian Wechsung

This review introduces the elasticity theory of two-dimensional crystals and nematic liquid crystals on curved surfaces, the energetics of topological defects (disclinations, dislocations and pleats) in these ordered phases, and the…

Soft Condensed Matter · Physics 2014-01-21 Vinzenz Koning , Vincenzo Vitelli

In this work, we investigate a particular class of shape optimization problems under uncertainties on the input parameters. More precisely, we are interested in the minimization of the expectation of a quadratic objective in a situation…

Optimization and Control · Mathematics 2015-06-01 M. Dambrine , C. Dapogny , H. Harbrecht

This work deals with shape optimization for contact mechanics. More specifically, the linear elasticity model is considered under the small deformations hypothesis, and the elastic body is assumed to be in contact (sliding or with Tresca…

Optimization and Control · Mathematics 2022-08-30 Bastien Chaudet-Dumas

This work focuses on steady and unsteady Navier-Stokes equations in a reduced order modeling framework. The methodology proposed is based on a Proper Orthogonal Decomposition within a levelset geometry description and the problems of…

Numerical Analysis · Mathematics 2023-08-08 Efthymios N. Karatzas , Monica Nonino , Francesco Ballarin , Gianluigi Rozza

In this chapter, we investigate recently proposed nonlinear conjugate gradient (NCG) methods for shape optimization problems. We briefly introduce the methods as well as the corresponding theoretical background and investigate their…

Optimization and Control · Mathematics 2025-10-14 Sebastian Blauth

We study the organization of topological defects in a system of nematogens confined to the two-dimensional sphere (S^2). We first perform Monte Carlo simulations of a fluid system of hard rods (spherocylinders) living in the tangent plane…

Soft Condensed Matter · Physics 2009-11-13 Homin Shin , Mark J. Bowick , Xiangjun Xing
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