# Enstrophy of Taylor-Green vortex **URL:** \ **Category:** General\ **Created:** [17 April 2024 14:46 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077 "2024-04-17T14:46:45Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [17 April 2024 14:46 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/1 "2024-04-17T14:46:45Z")
Hello, I want reproduce the result of the Taylor-Green vortex, and I used the ini file attached below. But the enstrophy is very small,such as 1e-7 magnitude, part of the intergate file shows as follows. I used 0.5_int-enst/(6.28_ 6.28\*6.28) to cpmpute the enstrophy. Could someone know why this happened? t,int-E,int-enst 0.0,61.88686627706847,0.0 0.4078656934018042,61.71802887873954,2.296300887116251e-08 0.8126183908977003,61.66268203880613,2.2212134292246567e-08 1.2169787745012177,61.58912752367325,2.1407088724571597e-08 1.6213517499473626,61.40097967914074,2.335030599623308e-08 2.024735988773325,61.32884987397709,2.340023530064617e-08 2.429111965244726,61.150483719028344,2.6112916912040565e-08 2.8334889495806497,60.97994750963156,2.8637945756793558e-08 3.2378705009449598,60.76012199832907,3.271690050704794e-08 3.6422420383489493,60.414482995681674,4.005853489985599e-08 4.046274631632653,60.08034786662381,5.033455666865129e-08 4.4506458091006325,59.53703404808475,6.748288945787687e-08 4.855020538699844,58.79887780590352,8.443631895397037e-08 5.258836914167074,57.89562220938521,9.719333586798353e-08 5.663215056052942,56.88529038770501,1.0474202893366631e-07 6.0673729685088995,55.788333167493114,1.1838002565398031e-07 6.471739485748487,54.511532291536916,1.310943058129848e-07 6.876105308222941,53.08500329326516,1.3945450301219878e-07 7.27852897903444,51.540097049753726,1.505466677746701e-07 7.682910004531521,49.74735830317027,1.7738844455941727e-07 8.080485954171163,47.732202932666794,2.1336828115703726e-07 8.484847463344611,45.39140036066121,2.2297014408616568e-07 8.888743802772288,42.920517827578934,2.2261182749731495e-07 9.293741641193087,40.55697054723922,2.1696698181250097e-07 9.698161132745843,38.31054255039028,2.180221050457046e-07 10.097959610421743,36.10005644885872,2.2224672633588195e-07 10.50255266267484,33.745063507787684,2.2150203913637967e-07 10.906976795193533,31.39102822601325,2.1523462619471398e-07 > [@TGV Performance Numbers](https://pyfr.discourse.group/t/tgv-performance-numbers/407): > > I was recently asked how Ampere GPUs compare to CPU, I have previously given some performance numbers, but decided to make more of a benchmark case for comparison. I ran a 40^3 hex mesh with p=3, which gives about 4.1 million solution points. The case I used was of course the TGV and below is the ini file. Given that we aren’t interested in the physics here, I only ran it to t=5. These results are using PyFR v 1.10, on a single A100, using CUDA 11.0.2 and GCC 9.2.0. Single Double Run… ---
**Author:** ![tdzanic](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@tdzanic](https://pyfr.discourse.group/u/tdzanic)\ **Post date:** [17 April 2024 17:45 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/2 "2024-04-17T17:45:45Z")
This is currently a bug in the develop branch in PyFR relating to the integrator plugin using `_vect_upts` for the gradients instead of `_grad_upts `. I believe changing that in: > fixes the problem on CUDA, but I’m not quite sure about other backends or if it might negatively interact with other features like kernel fusion. ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [17 April 2024 21:42 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/3 "2024-04-17T21:42:38Z")
Hi @fei can you try this branch (or implement the change in your version): [Comparing PyFR:develop...pv101:fusion-fix · PyFR/PyFR · GitHub](https://github.com/PyFR/PyFR/compare/develop...pv101:PyFR:fusion-fix) it should fix this issue as well as the issue with flux antialiasing for Navier Stokes being broken. ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [19 April 2024 23:14 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/4 "2024-04-19T23:14:14Z")
Hi @fei if you get a chance could you test this release candidate branch and see if it fixes your issues? [GitHub - PyFR/PyFR at release/v2.0.1](https://github.com/PyFR/PyFR/tree/release/v2.0.1) ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [20 April 2024 11:33 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/5 "2024-04-20T11:33:50Z")
Thanks a lot. I used this branch v2.0.1, the enstrophy is normally, but the kinetic energy dissipation rate is very strange. ![image](https://global.discourse-cdn.com/free1/uploads/pyfr/original/1X/1dd370f8668da9328a1d1ee45143c83ed72fcd3e.png) ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [20 April 2024 13:12 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/6 "2024-04-20T13:12:58Z")
Thanks. How did you obtain the plot? Did PyFR output the Ek and then you took the time derivative? Peter ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [20 April 2024 13:16 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/7 "2024-04-20T13:16:04Z")
I first used Ek = 0.5_int-E/(6.28_ 6.28\*6.28), then I took time derivative of the Ek. ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [20 April 2024 14:18 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/8 "2024-04-20T14:18:36Z")
Does this case use adaptive time stepping? If so, did you account for the variable time step when taking derivatives? What does the Ek plot look like? Peter ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [20 April 2024 14:28 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/9 "2024-04-20T14:28:45Z")
It now works. The nsteps of the [soln-plugin-integrate] can’t set too small, or it will occur oscillation. ---
**Author:** ![tdzanic](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@tdzanic](https://pyfr.discourse.group/u/tdzanic)\ **Post date:** [23 April 2024 18:49 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/10 "2024-04-23T18:49:39Z")
The oscillations in kinetic energy are due to using a constant density IC instead of an isothermal IC which causes oscillatory energy exchange between kinetic and internal energy at nonzero Mach number. Please use the TGV config file in [GitHub - PyFR/PyFR-Test-Cases](https://github.com/PyFR/PyFR-Test-Cases) which has isothermal ICs. ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [24 April 2024 14:26 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/11 "2024-04-24T14:26:38Z")
Thanks. I compared the Ek between the original PyFR2.0 and PyFR 2.0.1, and the result of the PyFR2.0 is more consistent with the reference value when t is 12-20. Have you ever encountered this problem? ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [24 April 2024 15:16 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/12 "2024-04-24T15:16:57Z")
Could you share plots to show exactly what the issue is? Peter ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [24 April 2024 15:37 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/13 "2024-04-24T15:37:42Z")
The test case is 64^3 elements, and P3 order. ![78fbf91ff337b1e91492830a6067c6f9](https://global.discourse-cdn.com/free1/uploads/pyfr/original/1X/37b513e5da53893d8d562820911156877bd23c89.png) ---
**Author:** ![tdzanic](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@tdzanic](https://pyfr.discourse.group/u/tdzanic)\ **Post date:** [24 April 2024 16:10 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/14 "2024-04-24T16:10:31Z")
Are these results obtained using identical .ini files for 2.0 and 2.0.1? ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [24 April 2024 23:54 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/15 "2024-04-24T23:54:03Z")
Yes, the ini file is same. ---
**Author:** ![tdzanic](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@tdzanic](https://pyfr.discourse.group/u/tdzanic)\ **Post date:** [25 April 2024 01:11 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/16 "2024-04-25T01:11:55Z")
What backend are you using and is the .ini file from the examples? My results for the kinetic energy are essentially identical between 2.0 and 2.0.1 for the example case. ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [25 April 2024 01:44 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/17 "2024-04-25T01:44:42Z")
The backend is openmp, and the .ini file is from the examples but with double precision. And I didn’t set the [backend-openmp] in the .ini file, I don’t know if that’s the reason. ---
**Author:** ![tdzanic](https://avatars.discourse-cdn.com/v4/letter/t/f05b48/32.png) [@tdzanic](https://pyfr.discourse.group/u/tdzanic)\ **Post date:** [25 April 2024 02:11 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/18 "2024-04-25T02:11:33Z")
I’m not running into the issue with the CUDA backend, and I can’t check the OpenMP backend myself. Can you try with ```auto [backend-openmp] cflags = -O3 ``` and see if that changes anything? ---
**Author:** ![p.vincent](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/p.vincent/32/225_2.png) [@p.vincent](https://pyfr.discourse.group/u/p.vincent)\ **Post date:** [25 April 2024 10:05 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/19 "2024-04-25T10:05:52Z")
I’d also be interested to know what version of numpy you have installed? ---
**Author:** ![fei](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@fei](https://pyfr.discourse.group/u/fei)\ **Post date:** [25 April 2024 10:28 UTC](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077/20 "2024-04-25T10:28:22Z")
Ok, I am trying with cflags = -O3. The version of numpy is 1.26.4. [Next page](https://pyfr.discourse.group/t/enstrophy-of-taylor-green-vortex/1077.md?page=2)