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Pencil Code User Meeting 2018 - Boulder
Pencil Code User Meeting 2018 - Boulder
11-15 June 2018 JILA
The Pencil Code User Meeting is an annual event where both experts and newcomers get together, learn about the code, and work towards improving it. There will also be a few science talks highlighting recent developments in which the Pencil Code played a role.

Most of the sessions can be followed via skype, zoom, or some other means. In order to participate in those, please register were a full participant and indicate this in the comments field in the registration.

Link to previous events:

Current Program (Draft!)

Monday, June 11

 9:00 Coffee, getting settled, informal discussions, t-shirts, etc
10:00 Opening the meeting (Axel)
10:30 Report from the Pencil Code Steering committee (Axel, Matthias)
10:45 Review of important code developments (Matthias)
11:30 Discussion
12:00 Lunch (C4C, please join other card holders, we'll be in the West garden)

14:30 (Wolfgang)
15:30 coffee
16:00 Physics of accretion in global simulations (Bhupendra Mishra)
17:00 Work in groups, inspection of the manual
      Discussion of the sound wave in a freely moving waggon problem
18:00 Dinner (downtown)

Tuesday, June 12

 9:00 Coffee, informal discussions
10:00 Instability in strongly magnetized accretion discs (Upasana Das)
10:30 Status on the special issue for GAFD (Axel, Simon, Fred)
11:00 Discussion on webpages and samples
12:00 Picnic by the creek between 28th and 30th (on the way to NSO/LASP)
      Here the creek is deep enough to jump and swim, so bring you
      swimming gear! Bring your own food or buy it from Safeway's at 28th.

--- Rest of the day will be at NSO, 3665 Discovery Dr, in W312 ---
----- Let me know if somebody needs to parking permit there ------

14:00 Major dynamo transitions in the Sun's evolution (Maarit & Co)
15:30 Global rotating hydromagnetic convection simulation (Petri)
16:30 BBQ on the balcony of NSO

Wednesday, June 13

 8:00 Breakfast at Chautauqua Dining Hall (self paid, sign up for table)
      We hope to sit outside on the balcony!
 9:00 Visit to
 9:15 Hike up between 1st and 2nd flatirons, bring water!
      Save sandals is ok (I use TeVas)
11:15 opportunity to return or to continue to Royal Arch.

14:00 late lunch at C4C (tbc)
15:00 remeshing issues (Wlad?)
15:30 Status of the Yin-Yang module (Matthias, Mariangela)
17:00 Work on webpages, update on soundwaves bouncing in a waggon
18:30 Light dinner at the Hill

Thursday, June 14

 9:00 GPU-PC (Maarit, Matthias, Johannes Pekkilä)
10:30 discussion/workshop on the Pencilnew framework
11:30 Rayleigh (Guest lecture, Nick Featherstone)
12:30 Lunch (C4C, please join other card holders, we'll be in the West garden)

14:00 Dedalus (Guest lecture, Ben Brown)
15:00 Cylindrical selfgravity and Poisson module (Vincent)
16:00 Informal presentation on open problems (Glen? tbc)
17:00 Discussion, programming
18:30 Dinner

Friday, June 15

 9:00 Heatflux & Boris correction in solar MHD simulations (Joern)
10:00 Early Universe magnetic fields (Sayan Mandal)
10:30 Gravitational waves (Alberto, Axel)
11:00 Code clean-up
12:00 Highly magnetized super-Chandrasekhar white dwarfs and their consequences
      (also announced as "Astrophysics Lunch Seminar")

14:30 Smagorinsky models in MHD (Petri)
15:00 Various items (auto-test, initialize with NaN, github emails,
      executable sizes
15:30 Coffee
16:00 update on slope limited diffusion (discussion/workshop)
17:00 Work on papers
18:00 Dinner

Conclusions of the meeting

Summary of the 14th Pencil Code User Meeting (Boulder 2018)

The meeting ran for a full week of 11-15 June 2018.
Out of the 19 registered participants, 8 were physically present while
the rest was connected via skype or zoom to specific sessions; see
Several of the participants reported on their working experience with
other codes, notably Pluto, Dedalus, Cosmos, CosmoHammer, and Athena.

* Axel presented the updated document "Scientific Usage of the Pencil
  Code" which now contains 475 research papers using the Pencil
  Code and an additional 68 papers referring to the Pencil Code; see Several
  science results we presented as part of this meeting, notably on
  accretion in global simulations and in strongly magnetized discs, on
  solar and stellar dynamo, the early universe, and super-Chandrasekhar
  white dwarfs.
* Matthias reported that the Terms of Reference of the Steering Committee
  were accepted by the majority of the owners.
* Wolfgang demonstrated the working of It is now configured
  such that every single check-in is being tested at level 2 (~30 tests).
* Axel reported that the special issue for Geophys. Astrophys. Fluid Dyn.
  is likely to contain at least 10 papers, of which 2 are currently being
  refereed and 8 others ones have been promised. The final deadline for
  accepted papers to be included in the special issue is, as previously
  announced, 15 January 2019. The two papers are available on the arXiv:
* The Tuesday afternoon session at the National Solar Observatory on
  "Major dynamo transitions in the Sun's evolution" was featured by the
  Goettingen group and was attended by over 30 people from several
  other groups in Boulder (notably the High Altitude Observatory and
  the Space Science Institute).
* Axel demonstrated that the remeshing routines worked in the case of
  gravitational wave, but he adjusted parts of the manual that referred
  to an old cvs repository. (The code had been on github/google-code
  for a number of years already.)
* Matthias reported that the Yin-Yang module works, but there may still
  be some bugs. Mariangela presented results for the magnetic field, which
  look clean, but there seem to be artifacts near the mesh boundaries
  that are most evident in the velocity field.
* Matthias and Axel gave an update on the use of 1-sided boundary
  conditions and an update on problem of sound waves bouncing back and
  forth in a freely moving wagon. Using an idl test, it turned out that
  the correct solution can only be obtained at high resolution when the
  diffusivity is large enough to resolve shocks.
* Matthias, Johannes Pekkilä, and Maarit gave an update on GPU-acceleration.
  A speedup by a factor of 7 was reported. Supercomputers with graphics
  cards on each node can now be used.
* Simon reported on the new python suite (Pencilnew), which is now
  basically complete. The old one still exists, which may still cause
* Guest lectures were given by Nick Featherstone on the Rayleigh code
  (a public spherical harmonics code), and by Ben Brown on the Dedalus
  code (a public multi-purpose code capable of solving initial value,
  boundary value, and eigenvalue problems spectrally and semi-implicitly of
  equations that are stated in symbolic form using a python interface).
  Ben sympathized with the idea to develop new benchmarks to test
  high-order aspects of 3-D codes (turbulence, dynamos, etc).
* Vince discussed the status of the cylindrical selfgravity and Poisson
  module. There is currently no z-extent.
* Joern discussed the status of the heatflux & Boris correction in solar
  MHD simulations.
* Sayan reported on early universe simulations and Alberto discussed
  the status of the gravitational wave module.
* Petri presented various magnetic LES modules. None of them seem to
  be safe when confronted with dynamo problems.
* Joern and Matthias gave an update on slope limited diffusion.
  There is still a problem with viscous heating. Attempts to fix this
  (r74486 of 18 May 2017) resulted in new problems. This change was revoked
  on 16 June 2018, but the heating problem is still not addressed.
* Joern urged future User Meeting organizers to fix the time well
  in advance. The 2019 meeting could potentially be at Aalto University
  (west of Helsinki). Possible time slots would include July 15-19, 22-26,
  July 29 - Aug 2, and August 5-9. Another option is still California.

Dates: from 11 June 2018 08:00 to 15 June 2018 18:00
Location: JILA
University of Colorado, JILA, 10th floor
Room: Foothills Room
Material: Link to previous meetings

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