Hi Spencer. Thanks for replying I wish you a great day, could you check this is my settings and I will be very grateful if Andera can send me his file at 3900 to check the settings. but also what about using a different time integration method *"BDFImplicitOrder2" *instead of using *"IMEXOrder2" in *"TimeIntegrationMethod" , I think the two of them are 2nd order but using Implicit instead of Implicit explicit will not crash, also I will keep CFL under 1 to be sure it is fine, I tried *"SpectralVanishingViscosity"* it is working but it is filtering my field when I checked the velocity spectrum it was filtered. Also another case , please check my attachment file it has the same settings even with lower Reynolds at 400 using velocity ratio is crashing, for outlet BC i am already using *HOutflowa.* ----------------------------------------------------------------- <?xml version="1.0" encoding="UTF-8" ?> <NEKTAR> <EXPANSIONS> <E COMPOSITE="C[1]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 1 Domain inlet plate upper --> <E COMPOSITE="C[2]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 2 Domain inlet plate lower --> <E COMPOSITE="C[3]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- ****3 Domain square faces up down front meshs**** --> <E COMPOSITE="C[4]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 4 Domain upper domain lower in up stream --> <E COMPOSITE="C[5]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 5 Domain upper lower downstream --> <E COMPOSITE="C[6]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- ***6 Domain down stream back side square*** --> <E COMPOSITE="C[7]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 7 Domain down stream after square big one --> <E COMPOSITE="C[8]" NUMMODES="3" FIELDS="u,v,w,p" TYPE="MODIFIED" /> <!-- 7 Domain down stream after square big one --> </EXPANSIONS> <CONDITIONS> <SOLVERINFO> * <I PROPERTY="SOLVERTYPE" VALUE="VelocityCorrectionScheme"/> <I PROPERTY="EQTYPE" VALUE="UnsteadyNavierStokes" /> <I PROPERTY="Projection" VALUE="Continuous" /> <I PROPERTY="EvolutionOperator" VALUE="Nonlinear" /> <I PROPERTY="TimeIntegrationMethod" VALUE="IMEXOrder2" /> <I PROPERTY="Driver" VALUE="Standard" /> <I PROPERTY="HOMOGENEOUS" VALUE="1D" /> <I PROPERTY="AdvectionForm" VALUE="SkewSymmetric" /> <I PROPERTY="Extrapolation" VALUE="Standard" /> <I PROPERTY="USEFFT" VALUE="FFTW" />* <!-- <I PROPERTY="DEALIASING" VALUE="ON" /> --> * <I PROPERTY="SPECTRALHPDEALIASING" VALUE="ON" />* <!-- <I PROPERTY="SpectralVanishingViscosity" VALUE="True" /> --> </SOLVERINFO> <PARAMETERS> <P> TimeStep = 0.0003 </P> <P> NumSteps = 550000 </P> <!-- 60sec --> <P> IO_CheckSteps = 5000 </P> <!-- 120 check files--> 520 <P> IO_InfoSteps = 10 </P> <P> Re = 2000 </P> <P> Kinvis = 1./Re </P> <P> IO_CFLSteps = 50 </P> <P> LZ = 10 </P> <!-- 3. * Fastest spanwise --> <P> HomModesZ = 16 </P> <!-- how many cells for Z direction --> </PARAMETERS> <VARIABLES> <V ID="0"> u </V> <V ID="1"> v </V> <V ID="2"> w </V> <V ID="3"> p </V> </VARIABLES> <BOUNDARYREGIONS> <B ID="0"> C[9] </B> <!-- Inlet1_upper --> <B ID="1"> C[10] </B> <!-- Inlet2_Lower --> <B ID="2"> C[11] </B> <!-- Splitter plate --> <B ID="3"> C[12] </B> <!-- Upper Boundary --> <B ID="4"> C[13] </B> <!-- Lower_Boundary --> <B ID="5"> C[14] </B> <!-- Outlet --> <B ID="6"> C[15] </B> <!-- Wall_square --> </BOUNDARYREGIONS> <BOUNDARYCONDITIONS> <REGION REF="0"> <!-- Inlet_upper --> <D VAR="u" VALUE="1" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0"/> </REGION> <REGION REF="1"> <!-- Inlet_lower --> <D VAR="u" VALUE="1" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0"/> </REGION> <REGION REF="2"> <!--Splitter plate --> <D VAR="u" VALUE="0" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> <REGION REF="3"> <!-- Upper Boundary --> <N VAR="u" USERDEFINEDTYPE="H" VALUE="0" /> <D VAR="v" VALUE="0" /> <N VAR="w" USERDEFINEDTYPE="H" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> <REGION REF="4"> <!-- Lower_Boundary --> <N VAR="u" USERDEFINEDTYPE="H" VALUE="0" /> <D VAR="v" VALUE="0" /> <N VAR="w" USERDEFINEDTYPE="H" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> <REGION REF="5"> <!-- Outlet --> * <N VAR="u" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <N VAR="v" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <N VAR="w" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <D VAR="p" USERDEFINEDTYPE="HOutflow" VALUE="0" /> * </REGION> <REGION REF="6"> <!-- WallA_square --> <D VAR="u" VALUE="0" /> <D VAR="v" VALUE="0" /> <D VAR="w" VALUE="0" /> <N VAR="p" USERDEFINEDTYPE="H" VALUE="0" /> </REGION> </BOUNDARYCONDITIONS> <!-- We initialise from pre-computed flow for speed --> <FUNCTION NAME="InitialConditions"> <E VAR="w" VALUE="awgn(1e-3)*cos(2*PI*z/LZ)" /> --> <!-- <F VAR="u,v,w,p" FILE="Start.chk" /> --> <!-- <E VAR="u,v,w,p" VALUE="0" /> --> <F VAR="u,v,p" FILE="Start2D.chk" /> <!-- start from 2D results --> </FUNCTION> <FUNCTION NAME="ExactSolution"> <E VAR="u" VALUE="0" /> <E VAR="v" VALUE="0" /> <E VAR="w" VALUE="0" /> <E VAR="p" VALUE="0" /> </FUNCTION> </CONDITIONS> ---------------------------------------------------------------------------------- Thanks, Regards On Sun, Jun 14, 2020 at 10:46 PM Sherwin, Spencer J < s.sherwin@imperial.ac.uk> wrote:
HI Reda,
I would definitely try Dealiasing, at least in the Spectral Element plane. Also you need to make sure the outflow boundary condition is not causing problems and possibly require HOUTFLOW conditions at the outflow?
The IMEXOrder2 is BDF2 on the linear viscous solve but we do not have a scheme to make the advection term implicit currently.
It should certainly run at Re=2000. We have a number of runs for a circular cylinder at Re=3900. @Andrea: Could you forward a session file for that?
Thanks, Spencer.
Spencer Sherwin FREng, FRAeS Head of Aerodynamics Section, Director of Research Computing Service, Professor of Computational Fluid Mechanics, Department of Aeronautics, s.sherwin@imperial.ac.uk South Kensington Campus, Phone: +44 (0)20 7594 5052 Imperial College London, Fax: +44 (0)20 7594 1974 London, SW7 2AZ, UK http://www.imperial.ac.uk/people/s.sherwin/
On 14 Jun 2020, at 07:15, sgepner@meil.pw.edu.pl wrote:
Hi Reda,
Have you tried using Dealliasing?
Pozdrawiam, Stanisław Gepner
14 cze 2020 01:32 Moto Light <redamansyhh@gmail.com> napisał(a):
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Hi All,
I wish all of you are fine these days, I am running a 3D homogeneous case for a square cylinder, when I run the case at high Reynolds 2000 it keeps crashing, I tried *"SpectralVanishingViscosity"* it is working but it is filtering my field, what about using a different time integration method *"BDFImplicitOrder2" *instead of using *"IMEXOrder2"*, I think the two of them are 2nd order but using Implicit instead of Implicit explicit will not crash, but also I will keep CFL under 1 to be sure it is fine, even with this method i can go for higher CFL, my Reynolds is 2000 turbulent flow.
Regards, Reda UPC Barcelona +34 632 675 853
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