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Welcome to the Nek5000 User Group!
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Jacob Bruney
8/11/20
Minimum Viscocity
Nek users, I am trying to simulate Euler equations and need to remove or minimize viscosity. I ran
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Minimum Viscocity
Nek users, I am trying to simulate Euler equations and need to remove or minimize viscosity. I ran
8/11/20
Teng, Ming
,
Tanmoy Chatterjee
3
8/6/20
Noises in budget terms
Hello Tanmoy, Thank you for the reply. I tried refinement by increasing polynomial order and it was
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Noises in budget terms
Hello Tanmoy, Thank you for the reply. I tried refinement by increasing polynomial order and it was
8/6/20
LAYLA FOURA
,
Haoran
2
8/4/20
Visualisation of the mesh and the geometry in NEK5000
Hi LAYLA, The mesh could be visualised by .fXXXXX file generated by running your case with Nek5000.
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Visualisation of the mesh and the geometry in NEK5000
Hi LAYLA, The mesh could be visualised by .fXXXXX file generated by running your case with Nek5000.
8/4/20
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M. Y. Li
Jan 10
Constant perturbation energy
Hi, I am performing a linear stability analysis of a periodically grooved channel flow using Nek5000.
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Constant perturbation energy
Hi, I am performing a linear stability analysis of a periodically grooved channel flow using Nek5000.
Jan 10
Bhargav Mantravadi
2
12/23/25
Ctarg related issue
Dear Team, Please ignore this email -- I have identified the issue. I can achieve CFL > 0.5 when
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Ctarg related issue
Dear Team, Please ignore this email -- I have identified the issue. I can achieve CFL > 0.5 when
12/23/25
Bibhas Kumar
12/19/25
axisymmetric simulation with a hybrid mesh
Hello everyone, I am encountering convergence issues during the pressure solver initialization in
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axisymmetric simulation with a hybrid mesh
Hello everyone, I am encountering convergence issues during the pressure solver initialization in
12/19/25
MWTWM M
12/19/25
DIV(V)-QTL too large!
Dear community, In my simulation case, a warning as shown in the figure below has appeared. It is
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DIV(V)-QTL too large!
Dear community, In my simulation case, a warning as shown in the figure below has appeared. It is
12/19/25
Bibhas Kumar
,
Fischer, Paul
4
12/17/25
Using 'A ' BC for axisymmetric formulation on elements with face ID: not 1
In Nek5000, the x axis is the axis of rotation. It is critical that vertex 1 and 2 of each element
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Using 'A ' BC for axisymmetric formulation on elements with face ID: not 1
In Nek5000, the x axis is the axis of rotation. It is critical that vertex 1 and 2 of each element
12/17/25
Sai Pranay
, …
Filipe Brandao
6
12/15/25
Boundary ID after n2to3
Hi YuHsiang, So in usrdat or usrdat2, I would only need to set BCs for IDs 1, 2 and 3 correct? Em
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Boundary ID after n2to3
Hi YuHsiang, So in usrdat or usrdat2, I would only need to set BCs for IDs 1, 2 and 3 correct? Em
12/15/25
Bhargav Mantravadi
,
YuHsiang Lan
3
12/14/25
Velocity gradient tensor
Hi Yu-Hsiang, Thank you very much for your reply and the helpful input. I have noted your suggestions
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Velocity gradient tensor
Hi Yu-Hsiang, Thank you very much for your reply and the helpful input. I have noted your suggestions
12/14/25
khanhh...@gmail.com
, …
Yuan, Haomin
3
12/11/25
Solve Energy equation with periodic BC in Nek5000
Hi, you need to add an sink or source to your energy equation. So you are solving temperature variant
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Solve Energy equation with periodic BC in Nek5000
Hi, you need to add an sink or source to your energy equation. So you are solving temperature variant
12/11/25
Chunheng Zhao
,
Fischer, Paul
2
12/9/25
gather scatter for surface integral
Dear Chunheng, The code below (also included as attachment) shows how to compute a surface integral
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gather scatter for surface integral
Dear Chunheng, The code below (also included as attachment) shows how to compute a surface integral
12/9/25
Filipe Brandao
, …
YuHsiang Lan
8
12/8/25
Issue running a 2D coarse mesh
It works when adjusting the header of the .re2 file. However when doing the same for a 3D mesh, it
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Issue running a 2D coarse mesh
It works when adjusting the header of the .re2 file. However when doing the same for a 3D mesh, it
12/8/25
MWTWM M
,
YuHsiang Lan
3
12/8/25
Why should HEX20 elements be used instead of HEX8 elements?
Dear YuHsiang Lan Thanks for your answer, it really helps. Student Ma On Monday, December 8, 2025 at
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Why should HEX20 elements be used instead of HEX8 elements?
Dear YuHsiang Lan Thanks for your answer, it really helps. Student Ma On Monday, December 8, 2025 at
12/8/25
MWTWM M
,
Yuan, Haomin
3
12/4/25
exo2nek
Dear Haomin (Kirk) Yuan Thanks for your answer, it really helps. Student Ma On Thursday, December 4,
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exo2nek
Dear Haomin (Kirk) Yuan Thanks for your answer, it really helps. Student Ma On Thursday, December 4,
12/4/25
James Johnson
12/2/25
Flat Plate RANS Divergence
Hello, I have been trying the k-tau RANS model on a 2D flat plate geometry with boundary conditions
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Flat Plate RANS Divergence
Hello, I have been trying the k-tau RANS model on a 2D flat plate geometry with boundary conditions
12/2/25
Bhargav Mantravadi
,
YuHsiang Lan
3
12/1/25
Spherical shell geometry
Hi Yu-Hsiang, Thank you very much for your response. I checked the BCs, and the .rea file generated
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Spherical shell geometry
Hi Yu-Hsiang, Thank you very much for your response. I checked the BCs, and the .rea file generated
12/1/25
Nils Benedikt
, …
Philipp Schlatter
10
12/1/25
Simulation crashes after partitioning elements to MPI ranks
Hi everyone, Just in case anyone stumbles upon this thread in the future wondering how to resolve
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Simulation crashes after partitioning elements to MPI ranks
Hi everyone, Just in case anyone stumbles upon this thread in the future wondering how to resolve
12/1/25
春风复苏
11/30/25
The overwriting issue with restarted computations
Hello everyone in the community, I ran a simulation for a while and finally obtained foo0.f00100. I
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The overwriting issue with restarted computations
Hello everyone in the community, I ran a simulation for a while and finally obtained foo0.f00100. I
11/30/25
春风复苏
,
YuHsiang Lan
4
11/30/25
Promble of "makenek ldcob"
Thank you for reminding me. I actually tried adding "-mcmodel=large" into PPLIST (makenek)
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Promble of "makenek ldcob"
Thank you for reminding me. I actually tried adding "-mcmodel=large" into PPLIST (makenek)
11/30/25
MWTWM M
11/25/25
Immersed Boundary Method (IBM)
Dear community, Within a numerical simulation framework based on the Immersed Boundary Method (IBM),
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Immersed Boundary Method (IBM)
Dear community, Within a numerical simulation framework based on the Immersed Boundary Method (IBM),
11/25/25
春风复苏
,
YuHsiang Lan
4
11/22/25
Parallel run shows partial lid velocity in 3D cavity flow
Thank you very much. On Sunday, October 26, 2025 at 11:24:06 PM UTC+8 YuHsiang Lan wrote: Hi, I'm
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Parallel run shows partial lid velocity in 3D cavity flow
Thank you very much. On Sunday, October 26, 2025 at 11:24:06 PM UTC+8 YuHsiang Lan wrote: Hi, I'm
11/22/25
Bibhas Kumar
, …
YuHsiang Lan
5
11/15/25
Robin BC 'c' vs flux BC 'f'
Hi YuHsiang, That's interesting. Thanks for suggesting. That's helpful. Best, Bibhas On
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Robin BC 'c' vs flux BC 'f'
Hi YuHsiang, That's interesting. Thanks for suggesting. That's helpful. Best, Bibhas On
11/15/25
MWTWM M
,
Bastien B. - LHEEA - Centrale Nantes
3
11/14/25
Boundary layer treatment of wavy or sawtooth-shaped meshes
Dear Bastien Thanks for your answer, it really helps. Student Ma On Friday, November 14, 2025 at 5:32
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Boundary layer treatment of wavy or sawtooth-shaped meshes
Dear Bastien Thanks for your answer, it really helps. Student Ma On Friday, November 14, 2025 at 5:32
11/14/25
George
11/14/25
ZPG turbulent flat-plate boundary layer setup and test case
Dear Nek community, I am a newcomer to Nek5000. I would like to ask for some guidance on how to set
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ZPG turbulent flat-plate boundary layer setup and test case
Dear Nek community, I am a newcomer to Nek5000. I would like to ask for some guidance on how to set
11/14/25
Yinglu Peng
, …
Dimitrios K. Fytanidis
5
11/1/25
Prenek GUI not displaying correctly on Ubuntu (VMware, Xorg)
Hi all, I tried modifying the font settings in xdriver.c as suggested in previous discussions (
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Prenek GUI not displaying correctly on Ubuntu (VMware, Xorg)
Hi all, I tried modifying the font settings in xdriver.c as suggested in previous discussions (
11/1/25
Yinglu Peng
,
YuHsiang Lan
3
11/1/25
Questions about creating 3D cylindrical meshes or simulating flow past a sphere in Nek5000 v19.0
Hi! I'm currently generating a geometry where the circle size depends on its radius. I plan to
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Questions about creating 3D cylindrical meshes or simulating flow past a sphere in Nek5000 v19.0
Hi! I'm currently generating a geometry where the circle size depends on its radius. I plan to
11/1/25
Chunheng Zhao
10/29/25
Jacobine error
Hi Neks, I have a Jacobine error from my simulation. It is not always there. Sometimes, it runs fine,
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Jacobine error
Hi Neks, I have a Jacobine error from my simulation. It is not always there. Sometimes, it runs fine,
10/29/25
Pau Fradera
,
X. G. Zhou
5
10/29/25
Output turbulent scalar fluxes
Dear Community, I wanted to remind about this message I sent a while ago. I would greatly appreciate
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Output turbulent scalar fluxes
Dear Community, I wanted to remind about this message I sent a while ago. I would greatly appreciate
10/29/25
Bastien B. - LHEEA - Centrale Nantes
, …
YuHsiang Lan
16
10/24/25
Full_restart crash due to MPI_Win_Create bug
Hi Bastien, Because you are using full_restart, if_full_pres is turned on. Otherwise, it's off by
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Full_restart crash due to MPI_Win_Create bug
Hi Bastien, Because you are using full_restart, if_full_pres is turned on. Otherwise, it's off by
10/24/25
j.simo...@gmail.com
,
YuHsiang Lan
2
10/15/25
Preconditioning pressure for 2.5D hydrodynamic stability calculations
Hi, Can you provide the equations you are solving? Do you also modify the matrix for the pressure
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Preconditioning pressure for 2.5D hydrodynamic stability calculations
Hi, Can you provide the equations you are solving? Do you also modify the matrix for the pressure
10/15/25
N SHIVA
10/8/25
How to speed up the simulation
Hi, I am working on a simaultion my local system with 13 core and 10 iteration per min I am getting.
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How to speed up the simulation
Hi, I am working on a simaultion my local system with 13 core and 10 iteration per min I am getting.
10/8/25
ME19B1026 SHIVA
,
X. G. Zhou
2
9/26/25
Genmap not connected error
Hi. It is suggested to upload your build.log or screenshot that indicates errors. I think it would be
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Genmap not connected error
Hi. It is suggested to upload your build.log or screenshot that indicates errors. I think it would be
9/26/25