# Parallel Computing Resources for the UK MHD Community

Lead Research Organisation:
University of Warwick

Department Name: Physics

### Abstract

Virtually all material in the universe consists of an ionised gas called a plasma. Plasmas conduct electricity and interact with magnetic fields, producing many physical phenomena not easily reproduced in laboratories on Earth. The large-scale behaviour of these plasmas can be predicted by using a known set of complicated mathematical equations, called the equations of Magnetohydrodynamics (MHD). The solutions of MHD equations can describe the behaviour of plasmas in which collisions dominate the physical processes, such as (i) the generation of magnetic fields through a process known as dynamo action, (ii) the release of a staggering amount of magnetic energy in a large solar flare by magnetic reconnection, (iii) the small scale chaotic motions of turbulence in a magnetised plasma, (iv) the fact that solar atmosphere is much hotter than the solar surface and (v) the way in which gigantic eruptions of solar plasma interact with the Earth's magnetic field to produce the Aurora. When collisional effects are weak, in low-density plasmas and in problems involving short length-scales, the more fundamental kinetic equations must be solved. However, the solution of both sets of equations require extremely large computers and the best way is to link several hundred computers together and get them all working on a fraction of the large problem. These computers are called parallel computers. The UK effort in this research area is at the forefront of the worldwide effort to understand how the Sun, the Solar System and astrophysical plasmas work. While this work is essentially theoretical, it is driven by the observations of the present fleet of solar and astrophysical ground and space-based observatories.

### Publications

Arber T
(2009)

*THERMAL FRONTS IN FLARING MAGNETIC LOOPS*in The Astrophysical Journal
Barker A
(2012)

*Magnetic buoyancy instabilities in the presence of magnetic flux pumping at the base of the solar convection zone Magnetic buoyancy and flux pumping*in Monthly Notices of the Royal Astronomical Society
Botha G
(2011)

*CHROMOSPHERIC RESONANCES ABOVE SUNSPOT UMBRAE*in The Astrophysical Journal
Botha G
(2010)

*Thermal conduction effects on the kink instability in coronal loops*in Astronomy & Astrophysics
Botha G
(2012)

*OBSERVATIONAL SIGNATURES OF THE CORONAL KINK INSTABILITY WITH THERMAL CONDUCTION*in The Astrophysical Journal
Bushby P
(2012)

*Convectively driven dynamo action in the quiet Sun*in Geophysical & Astrophysical Fluid Dynamics
Favier B
(2013)

*On the problem of large-scale magnetic field generation in rotating compressible convection*in Journal of Fluid Mechanics
Favier B
(2012)

*How can large-scale twisted magnetic structures naturally emerge from buoyancy instabilities? Magnetic structures from buoyancy instability*in Monthly Notices of the Royal Astronomical Society
Favier B
(2013)

*Kinematic dynamo action in square and hexagonal patterns.*in Physical review. E, Statistical, nonlinear, and soft matter physics
Favier B
(2013)

*Growth rate degeneracies in kinematic dynamos.*in Physical review. E, Statistical, nonlinear, and soft matter physics
Graf Von Der Pahlen J
(2014)

*The effect of guide-field and boundary conditions on collisionless magnetic reconnection in a stressed X -point collapse*in Physics of Plasmas
Gruszecki M
(2010)

*Phenomenon of Alfvénic vortex shedding.*in Physical review letters
Gruszecki M
(2012)

*Intensity variations associated with fast sausage modes*in Astronomy & Astrophysics
Gruszecki M
(2011)

*Magnetoacoustic shock formation near a magnetic null point*in Astronomy & Astrophysics
Gruszecki M
(2011)

*Slow magnetacoustic waves in magnetic arcades*in Astronomy & Astrophysics
Meyrand R
(2016)

*Direct Evidence of the Transition from Weak to Strong Magnetohydrodynamic Turbulence.*in Physical review letters
Meyrand R
(2018)

*Coexistence of Weak and Strong Wave Turbulence in Incompressible Hall Magnetohydrodynamics*in Physical Review X
Pechhacker R
(2014)

*Three-dimensional particle-in-cell simulation of electron acceleration by Langmuir waves in an inhomogeneous plasma*in Physics of Plasmas
Pechhacker R
(2012)

*Electron cyclotron maser emission mode coupling to the z-mode on a longitudinal density gradient in the context of solar type III bursts*in Physics of Plasmas
Pechhacker R
(2012)

*The effect of electron beam pitch angle and density gradient on solar type III radio bursts*in Physics of Plasmas
Schmitz H
(2013)

*The effect of initial conditions on the electromagnetic radiation generation in type III solar radio bursts*in Physics of Plasmas
Silvers L
(2009)

*DOUBLE-DIFFUSIVE INSTABILITIES OF A SHEAR-GENERATED MAGNETIC LAYER*in The Astrophysical Journal
Skender M
(2014)

*Whistler wave generation by non-gyrotropic, relativistic, electron beams*in Physics of Plasmas
Skinner D
(2013)

*Double-diffusive magnetic buoyancy instability in a quasi-two-dimensional Cartesian geometry*in Monthly Notices of the Royal Astronomical Society
Srivastava A
(2013)

*Simulation of the observed coronal kink instability and its implications for the SDO/AIA*in Advances in Space Research
Threlfall J
(2012)

*Nonlinear wave propagation and reconnection at magnetic X-points in the Hall MHD regime*in Astronomy & Astrophysics
Tsiklauri D
(2011)

*Particle acceleration by circularly and elliptically polarised dispersive Alfven waves in a transversely inhomogeneous plasma in the inertial and kinetic regimes*in Physics of Plasmas
Tsiklauri D
(2011)

*An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts*in Physics of Plasmas
Tsiklauri D
(2012)

*Three dimensional particle-in-cell simulation of particle acceleration by circularly polarised inertial Alfven waves in a transversely inhomogeneous plasma*in Physics of Plasmas
Tsiklauri D
(2014)

*Three dimensional magnetohydrodynamic simulation of linearly polarised Alfven wave dynamics in Arnold-Beltrami-Childress magnetic field*in Physics of Plasmas
Tsiklauri D
(2011)

*Galaxy rotation curves: the effect of $\vec{j} \times\vec{B}$ force*in Astrophysics and Space Science
Von Der Pahlen J
(2014)

*Octupolar out-of-plane magnetic field structure generation during collisionless magnetic reconnection in a stressed X -point collapse*in Physics of PlasmasDescription | The computations carried out with this equipment has shown us how magnetic fields play a crucial role in many astrophysical objects such as stars, accretion discs and galaxies. |

Exploitation Route | Our work has stimulated others to use many of our computational techniques to study astrophysical magnetic fields. The UKMHD Consortium is still an active user of UK computational resources through the STFC DiRAC facilities. As this facility under this award ended in 2012 recent publications and outcomes are now attributed to the DiRAC facility. |

Sectors | Education |

Description | This award is for a computing facility for UK MHD researchers. As well as contributing to our understanding of the role of magnetic fields in Astrophysical objects, it has also led to the development of numerical algorithms with more general application. The work of UK MHD continues but now has access to computing resources through the STFC DiRAC facility. |

Description | CCP Flagship Project |

Amount | £380,448 (GBP) |

Funding ID | EP/M011534/1 |

Organisation | Engineering and Physical Sciences Research Council (EPSRC) |

Sector | Public |

Country | United Kingdom |

Start | 04/2015 |

End | 03/2018 |

Description | H2020-PROTEC-2014 |

Amount | € 386,531 (EUR) |

Funding ID | 637302 - PROGRESS |

Organisation | European Commission |

Sector | Public |

Country | European Union (EU) |

Start | 01/2015 |

End | 12/2017 |

Description | UKMHD Consortium |

Organisation | University of Leeds |

Department | School of Mathematics Leeds |

Country | United Kingdom |

Sector | Academic/University |

PI Contribution | Warwick was a host site for one of three HPC clusters bought for the UKMHD Consortium. The Consortium is UK wide and has over 40 members in University academic groups. Warwick managed a compute resource available for the whole consortium. |

Collaborator Contribution | Two additional HPC clusters were procured and managed for the UKMHD Consortium by the Universities of Leeds and St Andrews. |

Impact | In total across the three HPC sites procured under this grant there have been around 200 publications resulting from work done on the UKMHD Consortium clusters. |

Description | UKMHD Consortium |

Organisation | University of St Andrews |

Department | School of Mathematics and Statistics |

Country | United Kingdom |

Sector | Academic/University |

PI Contribution | Warwick was a host site for one of three HPC clusters bought for the UKMHD Consortium. The Consortium is UK wide and has over 40 members in University academic groups. Warwick managed a compute resource available for the whole consortium. |

Collaborator Contribution | Two additional HPC clusters were procured and managed for the UKMHD Consortium by the Universities of Leeds and St Andrews. |

Impact | In total across the three HPC sites procured under this grant there have been around 200 publications resulting from work done on the UKMHD Consortium clusters. |