Dear all, I am computing the one dimensional Shu-Osher problem using DG of the CompressibleFlowSolver. I found one tricky problem. The initial condition contains a shock. When I set the initial conditions like the following <FUNCTION NAME="InitialConditions"> <E VAR="rho" VALUE="3.857143*(x<=-4.0) + (1.0+0.2*sin(5*x))*(x>-4.0)"/> <E VAR="rhou" VALUE="3.857143*2.629369*(x<=-4.0) + 0.0*(x>-4.0)" /> <E VAR="rhov" VALUE="0.0" /> <E VAR="E" VALUE="(10.33333/(Gamma-1) + 0.5*3.857143*2.629369*2.629369)*(x<=-4.0) + (1.0/(Gamma-1))*(x>-4.0)"/> </FUNCTION> spurious oscillations would occur in the initial condition around x=-4.0 where the shock is located. Although I can arrange the mesh to make the shock lie just at the interface of two elements, only one value can be specified at x=-4.0, causing the spurious oscillations. However, for the DG method, two different values should be accepted at one element interface. Can anybody help me with this ? P.S.: Where can I find the version history of Nektar++, illustrating what is new in the newer version software compared with the older one? Best, Jian Yu
Hi Jian, I guess the challenge here is that the domain is continuous whilst the solution is discontinuous. So there is no external way to introduce the discontinuity since we evaluate it in terms of the coordinates. I guess it could be hardwired which would require going to the initial conditions section and writing a method to enforce the conditions you wish. Regarding the version history but I have to confess I do not know where it is currently being kept: @Dave, @Chris can you direct us to the history of the versions! Cheers, Spencer. On 22 Oct 2015, at 12:14, Jian Yu <yuj@buaa.edu.cn<mailto:yuj@buaa.edu.cn>> wrote: Dear all, I am computing the one dimensional Shu-Osher problem using DG of the CompressibleFlowSolver. I found one tricky problem. The initial condition contains a shock. When I set the initial conditions like the following <FUNCTION NAME="InitialConditions"> <E VAR="rho" VALUE="3.857143*(x<=-4.0) + (1.0+0.2*sin(5*x))*(x>-4.0)"/> <E VAR="rhou" VALUE="3.857143*2.629369*(x<=-4.0) + 0.0*(x>-4.0)" /> <E VAR="rhov" VALUE="0.0" /> <E VAR="E" VALUE="(10.33333/(Gamma-1) + 0.5*3.857143*2.629369*2.629369)*(x<=-4.0) + (1.0/(Gamma-1))*(x>-4.0)"/> </FUNCTION> spurious oscillations would occur in the initial condition around x=-4.0 where the shock is located. Although I can arrange the mesh to make the shock lie just at the interface of two elements, only one value can be specified at x=-4.0, causing the spurious oscillations. However, for the DG method, two different values should be accepted at one element interface. Can anybody help me with this ? P.S.: Where can I find the version history of Nektar++, illustrating what is new in the newer version software compared with the older one? Best, Jian Yu _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users Spencer Sherwin McLaren Racing/Royal Academy of Engineering Research Chair, Professor of Computational Fluid Mechanics, Department of Aeronautics, Imperial College London South Kensington Campus London SW7 2AZ s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052
participants (2)
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Jian Yu
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Sherwin, Spencer J