December 2016 - Nektar-users

Using Nektar for solving compressible flow case
by devabratasahoo＠campus.technion.ac.il 05 Dec '16

05 Dec '16

Hi All, I am trying using Nektar for solving the compressible flow over a cavity at Re - 10^7 per meter. I tried to set the parameters as per the user guide but the solution terminates saying "NaN error found during time integration". Initially, I used structured grid with fine mesh near the walls, but it didn't work. And when I use a coarse structured grid it runs for a while and then terminates saying the same issue. When I tried with a lesser Reynolds no. (0.3x10^7) and a coarse unstructured grid, I worked but had a very bad residual. The tutorials provided by Nektar are all cases of incompressible flow, which works fine. I can't find any examples of using compressible flow solver in the tutorials. Can anyone please give me an example of how to set the parameters and solver info for using compressible flow solver. And what changes in the parameters and solverinfo should be done to solve steady cases of compressible flow in Nektar. Thanking you. Regards, Dev

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Using OpenMP on Nektar Libraries.
by ashok jallepalli 05 Dec '16

05 Dec '16

Hi, I have the following snippet of code and would like to know what I am doing wrong below. Without parallelizing, if this loop look takes 0.01 seconds. When I use k threads, this function is taking k*0.01 seconds. (1) Is there a faster way to evaluate a local expansion at a bunch of points. Or i must assess them 1by1 (2) I tried num threads from k=2 to k=10. This behavior is consistent. always takes (k*0.01). Is this behavior consistent? #pragma omp parallel num_threads(k) for (int i =0 ; i < values.num_elements(); i++) { values[i] = lexp->PhysEvaluate(glCoords.at(i),el_Phys); } // Info lexp is localExpansionShPtr; // num_elements ~21 // In the program, I am replacing k with 2 .. 10 number Ashok.

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Nektar++ 4.3.5 Released
by Chris Cantwell 03 Dec '16

03 Dec '16

Dear all, We are pleased to announce the release of Nektar++ v4.3.5. This release includes a number of further bug fixes and minor enhancements to the 4.3 release: **Library:** - Fix issue with parallel output (!699) - Fix performance issue with iterative full solver (!693) - Fix bug in DG with hybrid meshes (!694) - Enforced precision on history point output (!706) **Documentation** - Update build instructions in user guide for Windows (!692) **Tester** - Fix bug in tester when no parameters specified for test executable (!701) As always, if you encounter any problems please feel free to contact us on the mailing list nektar-users(a)imperial.ac.uk. Cheers, Chris -- Chris Cantwell Imperial College London South Kensington Campus London SW7 2AZ Email: c.cantwell(a)imperial.ac.uk www.imperial.ac.uk/people/c.cantwell

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