# Analysis of Nonlinear Partial Differential Equations

Lead Research Organisation:
University of Oxford

Department Name: Mathematical Institute

### Abstract

Partial differential equations (PDEs) are equations that relate the partial derivatives, usually with respect to space and time coordinates, of unknown quantities. They are ubiquitous in almost all applications of mathematics, where they provide a natural mathematical description of phenomena in the physical, natural and social sciences, often arising from fundamental conservation laws such as for mass, momentum and energy. Significant application areas include geophysics, the bio-sciences, engineering, materials science, physics and chemistry, economics and finance. Length-scales of natural phenomena modelled by PDEs range from sub-atomic to astronomical, and time-scales may range from nanoseconds to millennia. The behaviour of every material object can be modelled either by PDEs, usually at various different length- or time-scales, or by other equations for which similar techniques of analysis and computation apply. A striking example of such an object is Planet Earth itself.Linear PDEs are ones for which linear combinations of solutions are also solutions. For example, the linear wave equation models electromagnetic waves, which can be decomposed into sums of elementary waves of different frequencies, each of these elementary waves also being solutions. However, most of the PDEs that accurately model nature are nonlinear and, in general, there is no way of writing their solutions explicitly. Indeed, whether the equations have solutions, what their properties are, and how they may be computed numerically are difficult questions that can be approached only by methods of mathematical analysis. These involve, among other things, precisely specifying what is meant by a solution and the classes of functions in which solutions are sought, and establishing ways in which approximate solutions can be constructed which can be rigorously shown to converge to actual solutions. The analysis of nonlinear PDEs is thus a crucial ingredient in the understanding of the world about us.As recognized by the recent International Review of Mathematics, the analysis of nonlinear PDEs is an area of mathematics in which the UK, despite some notable experts, lags significantly behind our scientific competitors, both in quantity and overall quality. This has a serious detrimental effect on mathematics as a whole, on the scientific and other disciplines which depend on an understanding of PDEs, and on the knowledge-based economy, which in particular makes increasing use of simulations of PDEs instead of more costly or impractical alternatives such as laboratory testing.The proposal responds to the national need in this crucial research area through the formation of a forward-looking world-class research centre in Oxford, in order to provide a sharper focus for fundamental research in the field in the UK and raise the potential of its successful and durable impact within and outside mathematics. The centre will involve the whole UK research community having interests in nonlinear PDEs, for example through the formation of a national steering committee that will organize nationwide activities such as conferences and workshops.Oxford is an ideal location for such a research centre on account of an existing nucleus of high quality researchers in the field, and very strong research groups both in related areas of mathematics and across the range of disciplines that depend on the understanding of nonlinear PDEs. In addition, two-way knowledge transfer with industry will be achieved using the expertise and facilities of the internationally renowned mathematical modelling group based in OCIAM which, through successful Study Groups with Industry, has a track-record of forging strong links to numerous branches of science, industry, engineering and commerce. The university is committed to the formation of the centre and will provide a significant financial contribution, in particular upgrading one of the EPSRC-funded lectureships to a Chair

### Publications

Kay D
(2009)

*Discontinuous Galerkin Finite Element Approximation of the Cahn-Hilliard Equation with Convection*in SIAM Journal on Numerical Analysis
Capdeboscq Y
(2009)

*Imaging by Modification: Numerical Reconstruction of Local Conductivities from Corresponding Power Density Measurements*in SIAM Journal on Imaging Sciences
Majumdar A
(2009)

*Landau-De Gennes Theory of Nematic Liquid Crystals: the Oseen-Frank Limit and Beyond*in Archive for Rational Mechanics and Analysis
Chen G
(2009)

*Uniqueness of transonic shock solutions in a duct for steady potential flow*in Journal of Differential Equations
Chen G
(2009)

*Large-time behavior of periodic entropy solutions to anisotropic degenerate parabolic-hyperbolic equations*in Proceedings of the American Mathematical Society
Kurzke M
(2009)

*Dynamics for Ginzburg-Landau vortices under a mixed flow*in Indiana University Mathematics Journal
Allaire G
(2009)

*Two asymptotic models for arrays of underground waste containers*in Applicable Analysis
Mielke A
(2009)

*Reverse Approximation of Energetic Solutions to Rate-Independent Processes*in Nonlinear Differential Equations and Applications NoDEA
Chen G
(2009)

*Evolution of Discontinuity and Formation of Triple-Shock Pattern in Solutions to a Two-Dimensional Hyperbolic System of Conservation Laws*in SIAM Journal on Mathematical Analysis
AMMARI H
(2009)

*Mathematical models and reconstruction methods in magneto-acoustic imaging*in European Journal of Applied Mathematics
Chen G
(2009)

*Isometric Immersions and Compensated Compactness*in Communications in Mathematical Physics
Peschka D
(2009)

*Thin-film rupture for large slip*in Journal of Engineering Mathematics
Rindler F
(2009)

*Optimal Control for Nonconvex Rate-Independent Evolution Processes*in SIAM Journal on Control and Optimization
Knezevic D
(2009)

*BAIL 2008 - Boundary and Interior Layers*
Luskin M
(2009)

*An Analysis of Node-Based Cluster Summation Rules in the Quasicontinuum Method*in SIAM Journal on Numerical Analysis
Kirr E
(2009)

*Asymptotic stability of ground states in 2D nonlinear Schrödinger equation including subcritical cases*in Journal of Differential Equations
Kristensen J
(2009)

*Relaxation of signed integral functionals in BV*in Calculus of Variations and Partial Differential Equations
Chen G
(2009)

*The Navier-Stokes equations with the kinematic and vorticity boundary conditions on non-flat boundaries*in Acta Mathematica Scientia
Koch G
(2009)

*Liouville theorems for the Navier-Stokes equations and applications*in Acta Mathematica
Chen G
(2009)

*Weak continuity of the Gauss-Codazzi-Ricci system for isometric embedding*in Proceedings of the American Mathematical Society
Knezevic D
(2009)

*A heterogeneous alternating-direction method for a micro-macro dilute polymeric fluid model*in ESAIM: Mathematical Modelling and Numerical Analysis
Chrusciel P
(2009)

*On higher dimensional black holes with Abelian isometry group*in Journal of Mathematical Physics
Chrusciel P
(2009)

*Topological Censorship for Kaluza-Klein Space-Times*in Annales Henri Poincaré
Herrmann M
(2009)

*Self-similar solutions for the LSW model with encounters*in Journal of Differential Equations
Beretta E
(2009)

*Thin cylindrical conductivity inclusions in a three-dimensional domain: a polarization tensor and unique determination from boundary data*in Inverse ProblemsDescription | This was a broad grant designed to help consolidate research on nonlinear partial differential equations in the UK. In particular the Oxford Centre for Nonlinear PDE was founded as a result of the grant and is now a leading international centre. As regards specific research advances, these were in various areas of applications of PDE, for example to fluid and solid mechnaics, liquid crystals, electromagnetism, and relativity. |

Exploitation Route | Through publications and consultation with current and former members of OxPDE. |

Sectors | Aerospace, Defence and Marine,Chemicals,Construction,Electronics,Energy,Environment |

URL | https://www0.maths.ox.ac.uk/groups/oxpde |

Description | Advanced Investigator Grant |

Amount | € 2,006,998 (EUR) |

Funding ID | 291053 |

Organisation | European Research Council (ERC) |

Sector | Public |

Country | Belgium |

Start | 03/2012 |

End | 03/2017 |