Hi Geordie,

I don’t know if there’s been a response to this query yet but I haven’t seen one. If not, apologies for the delay.

I’ve been able to reproduce the error you’re encountering on Ubuntu 18.04 using the packaged version of Nektar++. The packaged version will be the 5.0.0 release. There have been a number of changes in the master branch of the code in the GitLab repository since the 5.0.0 release and I can confirm that with a fresh build from the master branch, this error does not occur so I assume it has been resolved subsequent to 5.0.0.

This update will be included in a future release, however, in the meantime, if you’ve not already done so, you could try building Nektar++ from the source code available in GitLab. You can follow the instructions on the Getting Started page, using the details under the “Clone our git repository” section to get the source code rather than downloading the 5.0.0 release source code.

Hope this helps.

Kind regards,
Jeremy

On 7 Dec 2020, at 02:48, G. D. McBain <gdmcbain@protonmail.com> wrote:

This email from gdmcbain@protonmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list to disable email stamping for this address.
 
I'm just starting to learn Nektar++ from the tutorials and User Guide and mostly it's going very well, but I'm having trouble with FieldConvert -m gradient, hitting a segmentation fault.  I'm wondering whether I'm misunderstanding its use.

For example, after successfully running the basics-helmholtz example

    https://doc.nektar.info/tutorials/latest/basics/helmholtz/basics-helmholtz.html

    gmsh -2 Helm_mesh.geo
    Nekmesh Helm_mesh.msh Helm_mesh.xml
    ADRSolver -v Helm_mesh.xml Helm_conditions.xml
    FieldConvert Helm_mesh.xml Helm_conditions.xml Helm_mesh.fld Helm_mesh.vtu

to produce Helm_mesh.fld and Helm_mesh.vtu, I tried

    FieldConvert -m gradient Helm_mesh.xml Helm_conditions.xml Helm_mesh.fld Helm-grad.fld

following the documentation at

   https://doc.nektar.info/userguide/latest/user-guidese22.html#x35-1480005.5.12

but this raised

[levy:58744] *** Process received signal ***
[levy:58744] Signal: Segmentation fault (11)
[levy:58744] Signal code: Address not mapped (1)
[levy:58744] Failing at address: 0xb0
[levy:58744] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x3f040)[0x7f9d682b1040]
[levy:58744] [ 1] /usr/lib/x86_64-linux-gnu/libFieldUtils.so.5.0.0(_ZN6Nektar10FieldUtils11ProcessGrad7ProcessERN5boost15program_options13variables_mapE+0x6cc)[0x7f9d6a1aa7ac]
[levy:58744] [ 2] FieldConvert(_Z9RunModuleSt10shared_ptrIN6Nektar10FieldUtils6ModuleEERN5boost15program_options13variables_mapEb+0x3f)[0x55c3dbf99b8f]
[levy:58744] [ 3] FieldConvert(main+0x176c)[0x55c3dbf95e5c]
[levy:58744] [ 4] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f9d68293bf7]
[levy:58744] [ 5] FieldConvert(_start+0x2a)[0x55c3dbf9956a]
[levy:58744] *** End of error message ***
Segmentation fault (core dumped)

That's on Ubuntu 18.04, where I had installed nektar++ from http://www.nektar.info/ubuntu-bionic bionic/contrib, but I also get the same error on CentOS 7.7.1908, using the docker image nektarpp/nektar:244f4842.

What I was wanting to use the gradient module in my own project fpr was having solved for a steady incompressible potential flow with ADRSolver (EQTYPE "Laplace") to compute the velocity field as the gradient of the potential.

Thank you,
Geordie McBain

Sent from ProtonMail, Swiss-based encrypted email.


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