[H25E]

Hi, i'm the guy who was trying to make his engineering final project and arleady asked for help here before. I have achieved to simulate two car models but I have get really rare results:



We can see that there is negative pressure everywhere!! And also appears a high velocity zone at the end of the trail of the car. What can do a simulation outcomes like that?

In another angle:



There is 0 pressure at the start but it decays fast at negative values everywhere.
The initial conditions are the same of the motorBike tutorial, except changing "motorBike_.*" for "mystlname_.*"

At the second model, the simulation outcomes this...





As u can check i coudn't close the model in the wheels but, if bernoulli could see this simulation results he would run.

Anyone can help me? Thanks for your time.

[jherb]

Have you checked the influence of the up- and downstream boundaries on your results, meaning what happens if your wind channel gets longer?

[H25E]

Checking the simulations last night I found that the courant number was really high. I will do some checks and I will post again the progres here.

[RodriguezFatz]

You should at least tell us what solver, models, ... you are using. Also some log-output, fvSchemes and fvSolution and boundary conditions are needed if you want any usefull help. Of course what Joachim said could be a reason, but there can be like 1000 reasons. Without any more information about your case this won't work.

[H25E]

Yes, sorry. I'm using simpleFoam. All the boundary files, the fvSchemes and fvSolutions are the same of motorBike tutorial of simpleFoam, To reduce the courant number I decreased the deltaT of controldict of 1 down to 0.01 but that way some errors appeared while simulating that they didn't exist before modify the deltaT.

In the first simulation that is a porsche 911 appears that error:

--> FOAM FATAL IO ERROR: 
error in IOstream "/home/hector/Desktop/6porsche/1.42/U" for operation Ostream& operator<<(Ostream&, const char)

file: /home/hector/Desktop/6porsche/1.42/U at line 56473.

    From function IOstream::check(const char*) const
    in file db/IOstreams/IOstreams/IOstream.C at line 99.

FOAM exiting

And in the second simulation, of a bmw x6:

--> FOAM FATAL IO ERROR: 
error in IOstream "/home/hector/Desktop/blender2/4.42/phi" for operation Ostream& operator<<(Ostream&, const Scalar&)

file: /home/hector/Desktop/blender2/4.42/phi at line 299876.

    From function IOstream::check(const char*) const
    in file db/IOstreams/IOstreams/IOstream.C at line 99.

FOAM exiting

I can't give you the output log files of simpleFoam cause they are extremly long, but if you need to know something else tell me. With that deltaT courant number is still big, and it's a bit annoying cause it takes a long time to simulate.

Thanks for your time.

[RodriguezFatz]

H25E, first of all: SIMPLE is a steady state solver, that doesn't have any Courant number. If you change the "time step" in controlDict, the only things that is changed is the name of the directories where OpenFoam stores the data. The solver does exactly the same.
With just these two errors I need to guess. My guess is, that you try to restart the simulation from broken initial settings. I also guess that your initial settings (at times "1.42" in the first and "4.42" in the second case) are broken because you ended the simulation by pressing "cntrl + c" in the terminal during the "write" operation of that time step in openFoam. Just a guess...
Do you have the previous time step of these cases? Then, try to start with them.

[H25E]

Okay, thanks for the remark of courant number. In the past I had some similar IO error followed by an inability to boot linux, and now linux doesn't boot so... I will have to save data and reinstall linux. I will post my progress next days.

Thanks for your time