Hi All, I found the time-average field can not be used in a quasi 3d simulation by the compressible solver. it comes with the error: [ubuntu:10117] *** Process received signal *** [ubuntu:10117] Signal: Segmentation fault (11) [ubuntu:10117] Signal code: Address not mapped (1) [ubuntu:10117] Failing at address: 0x208 [ubuntu:10117] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x354b0)[0x7f5bcb64d4b0] [ubuntu:10117] [ 1] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar10FieldUtils5Field13AppendExpListEiNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEb+0x74)[0x7f5bce1ac454] [ubuntu:10117] [ 2] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar11SolverUtils18FilterFieldConvert12CreateFieldsERKNS_5ArrayINS_4OneDEKSt10shared_ptrINS_12MultiRegions7ExpListEEEE+0x334)[0x7f5bce1a6254] [ubuntu:10117] [ 3] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar11SolverUtils18FilterFieldConvert11OutputFieldERKNS_5ArrayINS_4OneDEKSt10shared_ptrINS_12MultiRegions7ExpListEEEEi+0xd1)[0x7f5bce1a8641] [ubuntu:10117] [ 4] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar11SolverUtils18FilterFieldConvert8v_UpdateERKNS_5ArrayINS_4OneDEKSt10shared_ptrINS_12MultiRegions7ExpListEEEERKd+0x417)[0x7f5bce1a9337] [ubuntu:10117] [ 5] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar11SolverUtils14UnsteadySystem9v_DoSolveEv+0xddf)[0x7f5bce1bbc2f] [ubuntu:10117] [ 6] /home/shujie/nektar++/build/dist/lib64/libSolverUtils.so.5.0.0b(_ZN6Nektar11SolverUtils14DriverStandard9v_ExecuteERSo+0x8e)[0x7f5bce1724ee] [ubuntu:10117] [ 7] CompressibleFlowSolver(main+0x27d)[0x4798cd] [ubuntu:10117] [ 8] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f5bcb638830] [ubuntu:10117] [ 9] CompressibleFlowSolver(_start+0x29)[0x4909a9] [ubuntu:10117] *** End of error message *** I put the test file on the attachment. I have tested it in Incompressible flow solver. It is fine. So I think maybe there is a bug in the compressible flow solver. But I am not looking deep into the code. So I can not find the problem. If someone has a solution, please let me. Kind regards, Shujie University of Southampton