March 2019 - Nektar-users - imperial.ac.uk

Inlet boundary conditions from a file
by Amitvikram Dutta 17 Mar '19

17 Mar '19

Hi all, Would it be possible to specify the inlet velocity boundary conditions of a 2D problem using a .pts file? I have a profile from my experiments that I wish to use as an inlet BC to my simulation. The user guide has an example where a file is used in combination with TIMEDEPENDENT BCs. My condition is not time varying and is essentially a 1D profile at the inflow of the domain. What would be the format of the file that I would specify? Sincerely, -- *Amitvikram Dutta* Graduate Research Assistant Fluid Mechanics Research Lab Multi-Physics Interaction Lab University of Waterloo

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Pressure inflow BC
by Amitvikram Dutta 17 Mar '19

17 Mar '19

Hi all, Is it possible to have a pressure boundary condition that guarantees inflow? I'd like to explain in more detail. I have a jet simulation where I'm attempting to simulate entrainment of the jet air from behind the jet. Unfortunately, at the boundaries at the to and bottom of the domain, where the flow should be coming into the domain, the flow instead goes out of the domain. I have set the BCs at this domain to be the same as for outlets, i.e., Zero velocity gradients and zero pressure. It was my hope that the velocities would settle to their correct value over the course of the simulation. However instead I ran into the problem just described. I'd appreciate some insight if possible. Sincerely, -- *Amitvikram Dutta* Graduate Research Assistant Fluid Mechanics Research Lab Multi-Physics Interaction Lab University of Waterloo

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Filed interpolation
by Moto Light 17 Mar '19

17 Mar '19

Hi All, i tried to make a 3D filed interpolation it is not working using FieldConvert -m interpfield:fromxml=file1.xml:fromfld=file1.fld file2.xml file2.fld file1.xml: was a combined file from the case file including the boundary conditions and the mesh file file2.xml the same for the new mesh and using the same domain with the same dimensions and got this error Segmentation fault (core dumped) ------------------ any suggestions for the field interpolation? Reda UPC.es

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please help
by Moto Light 13 Mar '19

13 Mar '19

Hi All, i am runing case 3D using 32 modes and using new version of Nektar++4.4.1 and after 2 sec in 3D solution i had this error //////////////// CG iterations made = 5001 using tolerance of 1e-09 (error = nan, rhs_mag = inf) ////////////////// and the simulation has been ended any one have idea what i can do to solve it wish you great day Reda

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Error in running the tutorial
by zxiong＠sas.upenn.edu 12 Mar '19

12 Mar '19

Dear all, When I try to compile the tutorial code of tutorial http://doc.nektar.info/tutorials/latest/fundamentals/differentiation/fundam… , I follow the instruction of task 1.1: I first use cmake command to generate makefile and then type 'make' but the terminal give me error messages like this:(I can successfully run tutorial code in http://doc.nektar.info/tutorials/latest/fundamentals/integration/fundamenta…, but I can't compile the code of this one). What should I do? *Scanning dependencies of target StdDifferentiation2D* [ 16%] Building CXX object CMakeFiles/StdDifferentiation2D.dir/StdDifferentiation2D.cpp.o */Users/zhenxiong/Desktop/independent_study/turotials/fundamentals-differentiation/tutorial/StdDifferentiation2D.cpp:57:21: **error: * * no viable overloaded '='* derivMatrixDir1 = LibUtilities::PointsManager()[quadPointsKeyDir1]->GetD(); * ~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3786:17: note: * candidate function not viable: no known conversion from 'const Nektar::LibUtilities::Points<double>::MatrixSharedPtrType' (aka 'const shared_ptr<NekMatrix<double> >') to 'const std::__1::shared_ptr<Nektar::NekMatrix<double, Nektar::StandardMatrixTag> >' for 1st argument shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3797:17: note: * candidate function not viable: no known conversion from 'const Nektar::LibUtilities::Points<double>::MatrixSharedPtrType' (aka 'const shared_ptr<NekMatrix<double> >') to 'std::__1::shared_ptr<Nektar::NekMatrix<double, Nektar::StandardMatrixTag> >' for 1st argument shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3794:9: note: * candidate template ignored: could not match 'std::__1::shared_ptr' against 'boost::shared_ptr' operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3805:9: note: * candidate template ignored: could not match 'std::__1::shared_ptr' against 'boost::shared_ptr' operator=(shared_ptr<_Yp>&& __r); * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3815:9: note: * candidate template ignored: could not match 'auto_ptr' against 'shared_ptr' operator=(auto_ptr<_Yp>&& __r); * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3839:9: note: * candidate template ignored: could not match 'unique_ptr' against 'shared_ptr' operator=(unique_ptr<_Yp, _Dp>&& __r); * ^* */Users/zhenxiong/Desktop/independent_study/turotials/fundamentals-differentiation/tutorial/StdDifferentiation2D.cpp:60:21: **error: * * no viable overloaded '='* derivMatrixDir2 = LibUtilities::PointsManager()[quadPointsKeyDir2]->GetD(); * ~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3786:17: note: * candidate function not viable: no known conversion from 'const Nektar::LibUtilities::Points<double>::MatrixSharedPtrType' (aka 'const shared_ptr<NekMatrix<double> >') to 'const std::__1::shared_ptr<Nektar::NekMatrix<double, Nektar::StandardMatrixTag> >' for 1st argument shared_ptr& operator=(const shared_ptr& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3797:17: note: * candidate function not viable: no known conversion from 'const Nektar::LibUtilities::Points<double>::MatrixSharedPtrType' (aka 'const shared_ptr<NekMatrix<double> >') to 'std::__1::shared_ptr<Nektar::NekMatrix<double, Nektar::StandardMatrixTag> >' for 1st argument shared_ptr& operator=(shared_ptr&& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3794:9: note: * candidate template ignored: could not match 'std::__1::shared_ptr' against 'boost::shared_ptr' operator=(const shared_ptr<_Yp>& __r) _NOEXCEPT; * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3805:9: note: * candidate template ignored: could not match 'std::__1::shared_ptr' against 'boost::shared_ptr' operator=(shared_ptr<_Yp>&& __r); * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3815:9: note: * candidate template ignored: could not match 'auto_ptr' against 'shared_ptr' operator=(auto_ptr<_Yp>&& __r); * ^* */Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:3839:9: note: * candidate template ignored: could not match 'unique_ptr' against 'shared_ptr' operator=(unique_ptr<_Yp, _Dp>&& __r); * ^* 2 errors generated. make[2]: *** [CMakeFiles/StdDifferentiation2D.dir/StdDifferentiation2D.cpp.o] Error 1 make[1]: *** [CMakeFiles/StdDifferentiation2D.dir/all] Error 2 make: *** [all] Error 2 Best, Zhen

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Nektar++ Workshop 2019 (10-12th June)
by Moxey, David 06 Mar '19

06 Mar '19

Dear all, This year we plan to continue our Nektar++ workshop series, continuing from the 2017 workshop and ICOSAHOM 2018 last year. The purpose of the Nektar++ workshop is to bring together developers and users of all experiences to hear about new and future developments in Nektar++ and some of the exciting science and engineering being undertaken by our users with the code. This year, we will host the workshop at the University of Exeter between 10-12th June 2019. The first two days will include a comprehensive programme of talks, from both developers and users, followed by a number of parallel informal group sessions allowing attendees to discuss and work on specific aspects of the code. We are very interested for members of our community to present at the workshop. If you are interested in presenting a talk, please contact me (d.moxey(a)exeter.ac.uk) no later than March 22nd. We will also be holding a small poster session; further details regarding this will be available nearer the time. The workshop is free to attend and will include refreshments/lunch, but unfortunately we will not be able to fund any travel, accommodation or dinner costs for participants. For more details, including on how to register, please visit: https://www.nektar.info/community/workshops/nektar-workshop-2019/ Many thanks, Dave -- Dr David Moxey, PhD MMath MIMA FHEA Senior Lecturer in Engineering d.moxey(a)exeter.ac.uk | tel: 01392 724764 | web: davidmoxey.uk Room K1, Innovation Centre, University of Exeter, Exeter, EX4 4RN, UK.

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Appropriate Polynomial Order
by Amitvikram Dutta 04 Mar '19

04 Mar '19

Hi all, I have 2 separate questions. On Pasquetti's paper where he carries out the investigation of the effect of SVV parameters on the flow past a cylinder, the polynomial orders used are very high i.e. N ~ 60 with roughly 10.8 million DOF. In contrast, in the AIAA paper "Implicit Large-Eddy Simulation of a Wingtip Vortex" , by Lombard et. al. the mesh uses tetrahedra and prismatic elements, adopts N = 6 and obtains roughly 16 million DOF. My question is therefore, if I'm using a simple structured mesh at a very low Re of 4000 is the choice of N=6 wihich corresponds roughly to 32 Million DOF in the 3D case appropriate? Or should I change to a much higher order as Pasquetti did in his study, while coarsening my "mesh" to achieve the same DOF as I currently have. Sincerely, -- *Amitvikram Dutta* Graduate Research Assistant Fluid Mechanics Research Lab Multi-Physics Interaction Lab University of Waterloo

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Re: [Nektar-users] FW: Error in apply Dong outflow BCs
by Amitvikram Dutta 03 Mar '19

03 Mar '19

Hi Spencer, This is a very simple 2 dimesnional mesh with no curved elements. So I do not think this is a meshing issue. In fact changing the outflow Robin BCs to a more conventional Nuemann form for velocity immediately allows the solution to run smoothly. Sincerely, On Wed, Feb 27, 2019 at 3:26 AM Amitvikram Dutta < amitvikram.dutta(a)uwaterloo.ca> wrote: > > ------------------------------ > *From:* nektar-users-bounces(a)imperial.ac.ukOn Behalf OfSherwin, Spencer J > *Sent:* February 27, 2019 3:25:43 AM (UTC-05:00) Eastern Time (US & > Canada) > *To:* Amitvikram Dutta > *Cc:* nektar-users > *Subject:* Re: [Nektar-users] Error in apply Dong outflow BCs > > Hi Amitvikram, > > What sort of mesh were you running? Perhaps this is a 3D element we have > not fully tested ? > > Cheers, > Spencer > > Sent from my iPhone > > On 27 Feb 2019, at 07:09, Amitvikram Dutta <amitvdutta23(a)gmail.com> wrote: > > Hi all, > > I'm testing out the Robin type BCs for the outflow as given in the user > guide. > Which takes the form of the following > > > <R VAR="u" USERDEFINEDTYPE="HOutflow" VALUE="0" PRIMCOEFF="D0/TimeStep"/> > <R VAR="v" USERDEFINEDTYPE="HOutflow" VALUE="0" PRIMCOEFF="D0/TimeStep"/> > <R VAR="p" USERDEFINEDTYPE="HOutflow" VALUE="0" > PRIMCOEFF="1.0/(D0*Kinvis)"/> > > Upon startup, this gives the error > > Fatal : Level 0 assertion violation > Could not identify matrix type from dimension > > I havent come across this error before. Could someone point out what the > error is? > SIncerely, > -- > > *Amitvikram Dutta* > > Graduate Research Assistant > > Fluid Mechanics Research Lab > > Multi-Physics Interaction Lab > > University of Waterloo > > _______________________________________________ > Nektar-users mailing list > Nektar-users(a)imperial.ac.uk > https://mailman.ic.ac.uk/mailman/listinfo/nektar-users > > -- *Amitvikram Dutta* Graduate Research Assistant Fluid Mechanics Research Lab Multi-Physics Interaction Lab University of Waterloo

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SVV for passive scalar transport
by Vishal Saini 03 Mar '19

03 Mar '19

Hi all, I'd like to study scalar mixing in the jets-in-cross-flow case using IncNavierStokesSolver (an SVV-LES simulation). According to the user guide, I can simply add a transport equation for a scalar in the condition file. However, I'm not sure what would be the easiest way to apply the SVV filter on the scalar field. Have someone tried this before? Any help is much appreciated. BR, Vishal --- *Vishal SAINI* Master of Research, University of Cambridge. Master in Turbulence EC Lille, ENSIP and ENSMAFrance. Contact: vs434(a)cam.ac.uk, vishal.saini.nitj(a)gmail.com <vishal.saini.nitj(a)gmail.com> (+44) 7 459 186 139 (UK) (+33) 7 58 24 84 02 (France)

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