******************* This email from originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Hello all! I want to use Nektar++ Compressible Flow Solver for modelling of supersonic flows and testing of different techniques of the shock-capturing in future. I have tried to run a simple test Forward Step (Woodward, Collela) by CompressibleFlowSolver, but some problems have appeared. The simulation is stable only for CFL = 0.001. Increasing of CFL causes a vacuum on the first step. My mesh resolution is 8 cells per step height. My settings: <EXPANSIONS> <E COMPOSITE="C[5]" NUMMODES="3" FIELDS="rho,rhou,rhov,E" TYPE="MODIFIED" /> </EXPANSIONS> <CONDITIONS> <PARAMETERS> <P> TimeStep = 0 </P> <P> CFL = 0.001 </P> <P> FinTime = 4.0 </P> <P> NumSteps = 0 </P> <P> IO_CheckSteps = 1000 </P> <P> IO_InfoSteps = 500 </P> <P> Gamma = 1.4 </P> <P> rhoInf = 1.0 </P> <P> uInf = 3.0 </P> <P> vInf = 0.0 </P> <P> pInf = 1.0 / Gamma </P> <P> mu = 1e-12 </P> <P> cInf = sqrt(Gamma * pInf / rhoInf) </P> <!--P> L = 1 </P--> <P> Skappa = -1.3 </P> <P> Kappa = 0.2 </P> <P> mu0 = 1.0 </P> </PARAMETERS> <SOLVERINFO> <I PROPERTY="EQType" VALUE="EulerCFE" /> <I PROPERTY="Projection" VALUE="DisContinuous" /> <I PROPERTY="AdvectionType" VALUE="FRDG" /> <I PROPERTY="DiffusionType" VALUE="LDGNS" /> <I PROPERTY="TimeIntegrationMethod" VALUE="RungeKutta2"/> <I PROPERTY="UpwindType" VALUE="ExactToro" /> <I PROPERTY="ProblemType" VALUE="General" /> <I PROPERTY="ShockCaptureType" VALUE="NonSmooth" /> <I PROPERTY="ViscosityType" VALUE="Constant" /> </SOLVERINFO> <VARIABLES> <V ID="0"> rho </V> <V ID="1"> rhou </V> <V ID="2"> rhov </V> <V ID="3"> E </V> <!--V ID="4"> eps </V--> </VARIABLES> <BOUNDARYREGIONS> <B ID="0"> C[1] </B> <B ID="1"> C[2] </B> <B ID="2"> C[3] </B> <B ID="3"> C[4] </B> </BOUNDARYREGIONS> <BOUNDARYCONDITIONS> <REGION REF="0"> <D VAR="rho" VALUE="rhoInf" /> <D VAR="rhou" VALUE="rhoInf*uInf" /> <D VAR="rhov" VALUE="0" /> <D VAR="E" VALUE="pInf / (Gamma - 1) + 0.5 * rhoInf * (uInf * uInf + vInf * vInf)" /> <!--D VAR="eps" VALUE="0" /--> </REGION> <REGION REF="1"> <D VAR="rho" USERDEFINEDTYPE="PressureOutflowNonReflective" VALUE="rhoInf" /> <D VAR="rhou" USERDEFINEDTYPE="PressureOutflowNonReflective" VALUE="rhoInf*uInf" /> <D VAR="rhov" USERDEFINEDTYPE="PressureOutflowNonReflective" VALUE="0" /> <D VAR="E" USERDEFINEDTYPE="PressureOutflowNonReflective" VALUE="pInf / (Gamma - 1) + 0.5 * rhoInf * (uInf * uInf + vInf * vInf)" /> <!--D VAR="eps" USERDEFINEDTYPE="PressureOutflow" VALUE="0" /--> </REGION> <REGION REF="2"> <D VAR="rho" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="rhou" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="rhov" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="E" USERDEFINEDTYPE="Wall" VALUE="0" /> <!--D VAR="eps" USERDEFINEDTYPE="Wall" VALUE="0" /--> </REGION> <REGION REF="3"> <D VAR="rho" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="rhou" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="rhov" USERDEFINEDTYPE="Wall" VALUE="0" /> <D VAR="E" USERDEFINEDTYPE="Wall" VALUE="0" /> <!--D VAR="eps" USERDEFINEDTYPE="Wall" VALUE="0" /--> </REGION> </BOUNDARYCONDITIONS> <FUNCTION NAME="InitialConditions"> <E VAR="rho" VALUE="rhoInf" /> <E VAR="rhou" VALUE="rhoInf * uInf" /> <E VAR="rhov" VALUE="rhoInf * vInf" /> <E VAR="E" VALUE="pInf / (Gamma - 1) + 0.5 * rhoInf * (uInf * uInf + vInf * vInf)" /> <!--E VAR="eps" VALUE="0" /--> </FUNCTION> </CONDITIONS> I’ll be very thankful for help! -- Best regards, Victoria Korchagva