• Peter Jacobs (19/19) Oct 06 2017 Eilmer is a simulation code for studying high-speed compressible
• Bastiaan Veelo (9/28) Oct 06 2017 Congtatulations on a job well done. Your motivation for use of
• Joakim (26/56) Oct 06 2017 I like how you have setup instructions and docs on your site.
• user1234 (8/16) Oct 07 2017 After reading the pdf i have a question:
• Peter Jacobs (5/23) Oct 09 2017 We did consider having the entire application in pure D code,
• Martin Nowak (3/15) Oct 07 2017 Thanks for the kind words. Indeed D seems to be at a sweet spot

Peter Jacobs <peterj mech.uq.edu.au> writes:

Eilmer is a simulation code for studying high-speed compressible 
flows.  Early versions were written in C and then C++.  Version 4 
is a complete rewrite in D, with Lua for configuration and 
run-time scripting.  Code and documentation may be found at 
http://cfcfd.mechmining.uq.edu.au/eilmer/

This note is principally to say thank you to all of the people 
who have made the D programming language and its ecosystem.  
Being mechanical engineers, we are occasional but serious 
programmers.  For a number of years, we struggled with C++ and a 
code base of growing complexity.  In 2014, we made a serious 
commitment to reworking the entire code into D. In mid-2017, the 
new code was complete enough for general use and it is currently 
being used in a fourth-year course on computational fluid 
dynamics.  The D programming language has enhanced our 
programming experience and, for that, we are grateful to the many 
people who have built the foundation upon which we build our flow 
simulation code.

Cheers,
Peter Jacobs and Rowan Gollan

Bastiaan Veelo <Bastiaan Veelo.net> writes:

On Friday, 6 October 2017 at 22:16:09 UTC, Peter Jacobs wrote:
 Eilmer is a simulation code for studying high-speed 
 compressible flows.  Early versions were written in C and then 
 C++.  Version 4 is a complete rewrite in D, with Lua for 
 configuration and run-time scripting.  Code and documentation 
 may be found at http://cfcfd.mechmining.uq.edu.au/eilmer/

 This note is principally to say thank you to all of the people 
 who have made the D programming language and its ecosystem.  
 Being mechanical engineers, we are occasional but serious 
 programmers.  For a number of years, we struggled with C++ and 
 a code base of growing complexity.  In 2014, we made a serious 
 commitment to reworking the entire code into D. In mid-2017, 
 the new code was complete enough for general use and it is 
 currently being used in a fourth-year course on computational 
 fluid dynamics.  The D programming language has enhanced our 
 programming experience and, for that, we are grateful to the 
 many people who have built the foundation upon which we build 
 our flow simulation code.

 Cheers,
 Peter Jacobs and Rowan Gollan

Congtatulations on a job well done. Your motivation for use of 
the D Programming Language is the same as ours. I found your 
paper describing the rewrite [1] very interesting, I think it 
deserves a more prominent mention here and on the usual news 
sites.

Bastiaan

[1] 
http://cfcfd.mechmining.uq.edu.au/eilmer/pdfs/T0316-eilmer-dlang-v2.pdf

Joakim <dlang joakim.fea.st> writes:

On Friday, 6 October 2017 at 23:49:33 UTC, Bastiaan Veelo wrote:
 On Friday, 6 October 2017 at 22:16:09 UTC, Peter Jacobs wrote:
 Eilmer is a simulation code for studying high-speed 
 compressible flows.  Early versions were written in C and then 
 C++.  Version 4 is a complete rewrite in D, with Lua for 
 configuration and run-time scripting.  Code and documentation 
 may be found at http://cfcfd.mechmining.uq.edu.au/eilmer/

 This note is principally to say thank you to all of the people 
 who have made the D programming language and its ecosystem.  
 Being mechanical engineers, we are occasional but serious 
 programmers.  For a number of years, we struggled with C++ and 
 a code base of growing complexity.  In 2014, we made a serious 
 commitment to reworking the entire code into D. In mid-2017, 
 the new code was complete enough for general use and it is 
 currently being used in a fourth-year course on computational 
 fluid dynamics.  The D programming language has enhanced our 
 programming experience and, for that, we are grateful to the 
 many people who have built the foundation upon which we build 
 our flow simulation code.

 Cheers,
 Peter Jacobs and Rowan Gollan

 Congtatulations on a job well done. Your motivation for use of 
 the D Programming Language is the same as ours. I found your 
 paper describing the rewrite [1] very interesting, I think it 
 deserves a more prominent mention here and on the usual news 
 sites.

 Bastiaan

 [1] 
 http://cfcfd.mechmining.uq.edu.au/eilmer/pdfs/T0316-eilmer-dlang-v2.pdf

I like how you have setup instructions and docs on your site.

Two relevant quotes from the paper:

"With the recent maturing of the programming language D as a good 
alternative to C++ for statically-checked, natively-compiled 
code, we have taken the opportunity to rebuild our simulation 
code. The D programming language provides the conveniences of 
Python, the run-time performance of C++ and the ability to be 
directly linked to C language libraries. It appears that we can 
have it all and we can have it now. One good example of where the 
rebuild has resulted in significant improvements is the 
viscous-flux calculation code. In the C++ code, about 2500 lines 
were used, and this had the extra complication of requiring the 
M4 preprocessor to produce the actual C++ code (of length 5580 
lines) that was given to the compiler. The new D language code 
amounts to 733 lines."

"Conclusion
We have spent much of a year building a new compressible flow 
simulation code from scratch, in a relatively new language. So 
far, our experience with the D programming language has been 
positive, with a fairly capable simulation code being constructed 
with a few months of effort by two people. Together with some 
code redesign, the D programming language has allowed the 
construction of a code base that is much simpler than its C++ 
predecessor but is just as fast."

Mike, want to stick this on proggit and HN?

user1234 <user1234 12.ie> writes:

On Friday, 6 October 2017 at 22:16:09 UTC, Peter Jacobs wrote:
 Eilmer is a simulation code for studying high-speed 
 compressible flows.  Early versions were written in C and then 
 C++.  Version 4 is a complete rewrite in D, with Lua for 
 configuration and run-time scripting.  Code and documentation 
 may be found at http://cfcfd.mechmining.uq.edu.au/eilmer/

 [...]

 Cheers,
 Peter Jacobs and Rowan Gollan

After reading the pdf i have a question:

Is LUA scripting too complex to be replaced by, let's say, pure D 
code, following a compile-time interface (i.e a duck type) ? I 
understand that existing LUA scripts must still be supported but 
since D is also known for its good speed of compilation perhaps 
the whole thing could be recompiled from scratch for a particular 
set of new scripts.

Peter Jacobs <peterj mech.uq.edu.au> writes:

On Saturday, 7 October 2017 at 09:29:42 UTC, user1234 wrote:
 On Friday, 6 October 2017 at 22:16:09 UTC, Peter Jacobs wrote:
 Eilmer is a simulation code for studying high-speed 
 compressible flows.  Early versions were written in C and then 
 C++.  Version 4 is a complete rewrite in D, with Lua for 
 configuration and run-time scripting.  Code and documentation 
 may be found at http://cfcfd.mechmining.uq.edu.au/eilmer/

 [...]

 Cheers,
 Peter Jacobs and Rowan Gollan

 After reading the pdf i have a question:

 Is LUA scripting too complex to be replaced by, let's say, pure 
 D code, following a compile-time interface (i.e a duck type) ? 
 I understand that existing LUA scripts must still be supported 
 but since D is also known for its good speed of compilation 
 perhaps the whole thing could be recompiled from scratch for a 
 particular set of new scripts.

We did consider having the entire application in pure D code, 
however, we find that Lua is an easier configuration language for 
our users, who are mostly non-coders.

Peter J.

Martin Nowak <code dawg.eu> writes:

On Friday, 6 October 2017 at 22:16:09 UTC, Peter Jacobs wrote:
 This note is principally to say thank you to all of the people 
 who have made the D programming language and its ecosystem.  
 Being mechanical engineers, we are occasional but serious 
 programmers.  For a number of years, we struggled with C++ and 
 a code base of growing complexity.  In 2014, we made a serious 
 commitment to reworking the entire code into D. In mid-2017, 
 the new code was complete enough for general use and it is 
 currently being used in a fourth-year course on computational 
 fluid dynamics.  The D programming language has enhanced our 
 programming experience and, for that, we are grateful to the 
 many people who have built the foundation upon which we build 
 our flow simulation code.

Thanks for the kind words. Indeed D seems to be at a sweet spot 
for scientific computation.