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March 3, 2009, 06:34 
Hi,
I am trying to solve a

#1 
New Member
Kieran Wood
Join Date: Mar 2009
Posts: 7
Rep Power: 9 
Hi,
I am trying to solve a flow for a supersonic engine intake (much like the one on the Blackbird aircraft) and am having problems specifying the BCs. All the ones I have tried bring up this error after a few iterations. [0] [0] [0] Maximum number of iterations exceeded#0 Foam::error::printStack(Foam:stream&) in "/home/kieran/OpenFOAM/OpenFOAM1.5/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::error::abort() in "/home/kieran/OpenFOAM/OpenFOAM1.5/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::calculate() in "/home/kieran/OpenFOAM/OpenFOAM1.5/lib/linuxGccDPOpt/libbasicThermophysicalMode ls.so" #3 Foam::hThermo<foam::puremixture<foam::consttranspo rt<foam::speciethermo<foam::hc onstthermo<foam::perfectgas> > > > >::correct() in "/home/kieran/OpenFOAM/OpenFOAM1.5/lib/linuxGccDPOpt/libbasicThermophysicalMode ls.so" #4 main in "/home/kieran/OpenFOAM/OpenFOAM1.5/applications/bin/linuxGccDPOpt/rhoCentralFoa m" #5 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #6 Foam::regIOobject::readIfModified() in "/home/kieran/OpenFOAM/OpenFOAM1.5/applications/bin/linuxGccDPOpt/rhoCentralFoa m" [0] [0] [0] From function specieThermo<thermo>::T(scalar f, scalar T0, scalar (specieThermo<thermo>::*F)(const scalar) const, scalar (specieThermo<thermo>::*dFdT)(const scalar) const) const [0] in file /home/dm2/henry/OpenFOAM/OpenFOAM1.5/src/thermophysicalModels/specie/lnInclude/ specieThermoI.H at line 78. My case needs a supersonic farfield inlet condition (which I am just using fixedValue for p, T, and U), and then two outlets one for the flow around the outside of the intake (using zeroGradient for p,T,U at the moment)  and one for the flow captured by the intake which needs to reach a lower total pressure in order to induce a shockwave (currently using inletOutlet for p and zeroGradient for T and U). For the second outlet I have also tried ouletInlet and fixedValue but get similar errors. Also am using the rhoCentralFoam solver. Does anyone know of a more appropriate BC for this case? Thanks in advance Kieran 

March 4, 2009, 21:58 
After looking at the flow befo

#2 
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Kieran Wood
Join Date: Mar 2009
Posts: 7
Rep Power: 9 
After looking at the flow before the error occurs it appears that two flows are being created giving a non physical solution. 1) the farfield inlet conditions set by fixed value BCs and 2) a pressure driven flow backwards into the domain from the inletOutlet BC.
I guess when these two flows meet the solver cannot handle the difference in total pressure and temperature well and so crashes with a thermoPhysicalModel error above. Is there a way to specify an outlet BC that maintains flow out of the domain and never acts as an inlet? A an average mass flux would be useful but how to specify it on the patch in the p, T, and U files? 

March 13, 2009, 07:37 
Hi,
I am still having probl

#3 
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Kieran Wood
Join Date: Mar 2009
Posts: 7
Rep Power: 9 
Hi,
I am still having problems solving my case and have tried all of the boundary condition combinations I could think of. Perhaps if I upload a picture of my case it will describe my problem more. Here is a picture of the mesh I am using. It is an axisymmetric case where there is a conical section inside a cowl. There is only a 2D slice shown but the case is 3D (90 degree segment with symmetry planes applied). The problem is that I cannot force any fixed values on the outlet2 since they are unknown (well I have an approximate expected value) and will be determined by the shock wave that forms between the cone and cowl lip. Instead what I need is to force the flow to always be out of the domain parallel to the X axis and never an inflow. Hopefully the flow will then choke itself and converge to a solution. My current boundaries (although the solution still crashes with an error similar to above) are, for p inlet { type fixedValue value uniform 101370 } outlet1 { type zeroGradient } outlet2 { type zeroGradient } + some symmetry planes for T inlet { type fixedValue value uniform 166.6 } outlet1 { type zeroGradient } outlet2 { type zeroGradient } + some symmetry planes for U inlet { type fixedValue value uniform (526.26 0 0) } outlet1 { type zeroGradient } outlet2 { type pressureDirectedInletVelocity; inletDirection uniform (1 0 0); value uniform (223 0 0); } + some symmetry planes The initial internal fields are set the same as the inlet values. The 223 is an approximate value of the expected velocity but as far as I know this is only an initial boundary value and will not affect the solution. Also i'm using rhoCentralFoam. If anyone knows a better way to set the boundaries to make the solution reach a steady state I would be grateful. Thanks Kieran 

September 10, 2010, 06:59 
My idea....

#4 
New Member
mahmood asgari
Join Date: Sep 2010
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You said : I know this is only an initial boundary value and will not affect the solution.BUT NO!!!
It is very important . you can change initial internal fields by subsonic and change back pressure for solving! because i had this problem later. 

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