# 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

Ball J
(2008)

*Orientable and Non-Orientable Line Field Models for Uniaxial Nematic Liquid Crystals*in Molecular Crystals and Liquid Crystals
Ball J
(2017)

*Mathematics and liquid crystals*in Molecular Crystals and Liquid Crystals
Kristensen J
(2008)

*Regularity in oscillatory nonlinear elliptic systems*in Mathematische Zeitschrift
Gallagher I
(2012)

*A profile decomposition approach to the $$L^\infty _t(L^{3}_x)$$ Navier-Stokes regularity criterion*in Mathematische Annalen
Condette N
(2010)

*Spectral approximation of pattern-forming nonlinear evolution equations with double-well potentials of quadratic growth*in Mathematics of Computation
Braides A
(2016)

*Asymptotic analysis of Lennard-Jones systems beyond the nearest-neighbour setting: A one-dimensional prototypical case*in Mathematics and Mechanics of Solids
Bulícek M
(2014)

*Analysis and approximation of a strain-limiting nonlinear elastic model*in Mathematics and Mechanics of Solids
LANGWALLNER B
(2011)

*EXISTENCE AND CONVERGENCE RESULTS FOR THE GALERKIN APPROXIMATION OF AN ELECTRONIC DENSITY FUNCTIONAL*in Mathematical Models and Methods in Applied Sciences
LARSEN C
(2012)

*EXISTENCE OF SOLUTIONS TO A REGULARIZED MODEL OF DYNAMIC FRACTURE*in Mathematical Models and Methods in Applied Sciences
HELMERS M
(2011)

*SNAPPING ELASTIC CURVES AS A ONE-DIMENSIONAL ANALOGUE OF TWO-COMPONENT LIPID BILAYERS*in Mathematical Models and Methods in Applied Sciences
BALL J
(2012)

*ON UNIQUENESS FOR TIME HARMONIC ANISOTROPIC MAXWELL'S EQUATIONS WITH PIECEWISE REGULAR COEFFICIENTS*in Mathematical Models and Methods in Applied Sciences
BURKE S
(2013)

*AN ADAPTIVE FINITE ELEMENT APPROXIMATION OF A GENERALIZED AMBROSIO-TORTORELLI FUNCTIONAL*in Mathematical Models and Methods in Applied Sciences
Ball J
(2014)

*An investigation of non-planar austenite-martensite interfaces*in Mathematical Models and Methods in Applied Sciences
BARRETT J
(2012)

*EXISTENCE AND EQUILIBRATION OF GLOBAL WEAK SOLUTIONS TO KINETIC MODELS FOR DILUTE POLYMERS II: HOOKEAN-TYPE MODELS*in Mathematical Models and Methods in Applied Sciences
HERRMANN M
(2012)

*OSCILLATORY WAVES IN DISCRETE SCALAR CONSERVATION LAWS*in Mathematical Models and Methods in Applied Sciences
NEGRI M
(2011)

*QUASI-STATIC CRACK PROPAGATION BY GRIFFITH'S CRITERION*in Mathematical Models and Methods in Applied Sciences
BARRETT J
(2011)

*EXISTENCE OF GLOBAL WEAK SOLUTIONS TO DUMBBELL MODELS FOR DILUTE POLYMERS WITH MICROSCOPIC CUT-OFF*in Mathematical Models and Methods in Applied Sciences
BARRETT J
(2011)

*EXISTENCE AND EQUILIBRATION OF GLOBAL WEAK SOLUTIONS TO KINETIC MODELS FOR DILUTE POLYMERS I: FINITELY EXTENSIBLE NONLINEAR BEAD-SPRING CHAINS*in Mathematical Models and Methods in Applied Sciences
Ball J
(2015)

*A probabilistic model for martensitic avalanches*in MATEC Web of Conferences
Ball J
(2015)

*Geometry of polycrystals and microstructure*in MATEC Web of Conferences
Dolzmann G
(2012)

*BMO and uniform estimates for multi-well problems*in Manuscripta Mathematica
Niethammer B
(2007)

*On Screening Induced Fluctuations in Ostwald Ripening*in Journal of Statistical Physics
Braides A
(2014)

*An Example of Non-Existence of Plane-Like Minimizers for an Almost-Periodic Ising System*in Journal of Statistical Physics
Herrmann M
(2010)

*Action Minimising Fronts in General FPU-type Chains*in Journal of Nonlinear Science
Fuchs M
(2008)

*Existence of global solutions for a parabolic system related to the nonlinear Stokes problem*in Journal of Mathematical Sciences
Ding M
(2013)

*Global existence and non-relativistic global limits of entropy solutions to the 1D piston problem for the isentropic relativistic Euler equations*in Journal of Mathematical Physics
Chrusciel P
(2009)

*On higher dimensional black holes with Abelian isometry group*in Journal of Mathematical Physics
Giannoulis J
(2008)

*Lagrangian and Hamiltonian two-scale reduction*in Journal of Mathematical Physics
Chen G
(2013)

*Stability of transonic characteristic discontinuities in two-dimensional steady compressible Euler flows*in Journal of Mathematical Physics
Iyer G
(2012)

*Coercivity and stability results for an extended Navier-Stokes system*in Journal of Mathematical Physics
Fang B
(2016)

*The uniqueness of transonic shocks in supersonic flow past a 2-D wedge*in Journal of Mathematical Analysis and Applications
Chrusciel P
(2010)

*On smoothness of black saturns*in Journal of High Energy Physics
Chen GG
(2018)

*Global Weak Rigidity of the Gauss-Codazzi-Ricci Equations and Isometric Immersions of Riemannian Manifolds with Lower Regularity.*in Journal of geometric analysis
Rindler F
(2014)

*A local proof for the characterization of Young measures generated by sequences in BV*in Journal of Functional Analysis
Peschka D
(2009)

*Thin-film rupture for large slip*in Journal of Engineering Mathematics
Ball J
(2014)

*Quasistatic Nonlinear Viscoelasticity and Gradient Flows*in Journal of Dynamics and Differential Equations
Chen G
(2009)

*Uniqueness of transonic shock solutions in a duct for steady potential flow*in Journal of Differential Equations
Barrett J
(2012)

*Existence of global weak solutions to finitely extensible nonlinear bead-spring chain models for dilute polymers with variable density and viscosity*in Journal of Differential Equations
Alberti G
(2016)

*Eulerian, Lagrangian and Broad continuous solutions to a balance law with non-convex flux I*in Journal of Differential Equations
Kirr E
(2009)

*Asymptotic stability of ground states in 2D nonlinear Schrödinger equation including subcritical cases*in Journal of Differential Equations
Breit D
(2012)

*Solenoidal Lipschitz truncation and applications in fluid mechanics*in Journal of Differential Equations
Herrmann M
(2009)

*Self-similar solutions for the LSW model with encounters*in Journal of Differential Equations
Duzaar F
(2007)

*The existence of regular boundary points for non-linear elliptic systems*in Journal für die reine und angewandte Mathematik (Crelles Journal)
Bourgain J
(2015)

*On the Morse-Sard property and level sets of W n ,1 Sobolev functions on R n*in Journal für die reine und angewandte Mathematik (Crelles Journal)
Ammari H
(2010)

*Progress on the strong Eshelby's conjecture and extremal structures for the elastic moment tensor*in Journal de Mathématiques Pures et Appliquées
Capdeboscq Y
(2013)

*On one-dimensional inverse problems arising from polarimetric measurements of nematic liquid crystals*in Inverse Problems
Beretta E
(2009)

*Thin cylindrical conductivity inclusions in a three-dimensional domain: a polarization tensor and unique determination from boundary data*in Inverse Problems
Bae M
(2008)

*Regularity of solutions to regular shock reflection for potential flow*in Inventiones mathematicae
Ortner C
(2011)

*Stress-based atomistic/continuum coupling: a new variant of the quasicontinuum approximation*in International Journal for Multiscale Computational Engineering
Kurzke M
(2009)

*Dynamics for Ginzburg-Landau vortices under a mixed flow*in Indiana University Mathematics JournalDescription | 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 |