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Old   November 10, 2004, 12:55
Default Warning 097-
  #1
AB
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Hi

I am trying to run the .mdl file by writing new geometry and problem files. But when I run star, the iteration stops after 4 iterations and gives me error as : *** WARNING #097 *** DIFFERENCING SCHEMES DIFFER FOR U, TE & TOTAL ENTHALPY.

Can you tell me how can I get rid of the errors and make the model run. There are lots of warnings in the .info file and if someone wants then i can send the .run and .info file for check.

And how to change the differencing schemes as I dont see anywhere the differencing schemes for Total Enthalpy , TE and U.

Will be waiting for response,

Thanks,

AB
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Old   November 11, 2004, 04:42
Default Re: Warning 097-
  #2
Richard
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The warning won't be the reason the run stopped: it's just telling you that you have ... well, exactly what it says. This is worth a warning because it can lead to higher discretization error. You said you had lots of warnings in the .info file - the clue as to why the run is failing is perhaps in one of those.
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Old   November 11, 2004, 13:14
Default Re: Warning 097-
  #3
Arnab
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Hi Richard,

it is true as to the warnings in the info file are the reasons for the simulation running after just 4 iterations.

there are lots of warnings in the info file and I am not able to make any sense of those warnings. can you or someone tell me what these warnings mean and how to get rid of these warnings..

some of the warnings in .info file are :

TIME STEP = 1; ELAPSED TIME = 0.500000E-03 s; LOAD STEP = 1

---------------------------------------------------------------------

MAXIMUM COURANT NUMBER = 0.000E+00 AT CELL 1 MEAN COURANT NUMBER = 0.000E+00

*** WARNING #007 *** SETTING T AT CELL 50 FROM -1.432E+03 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -1.099E+05 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 51 DENSITY= -2.4312E+02 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 52 DENSITY= -2.4694E+00 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 53 DENSITY= -2.0967E+00 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 54 DENSITY= -1.7588E+00 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 55 DENSITY= -1.4526E+00 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 56 DENSITY= -1.1751E+00 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 57 DENSITY= -9.2356E-01 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 58 DENSITY= -6.9560E-01 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 59 DENSITY= -4.8899E-01 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 60 DENSITY= -3.0174E-01 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 61 DENSITY= -1.3203E-01 LIMITER APPLIED

*** WARNING #065 *** OUT OF BOUNDS VALUE -3.2903E+05 FOR SCALAR VARIABLE ENTH AT CELL 51. CORRECTIVE ACTION TAKEN

*** WARNING #007 *** SETTING T AT CELL 50 FROM -1.432E+03 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -1.099E+05 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -1.432E+03 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -1.099E+05 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -1.432E+03 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -1.099E+05 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -1.432E+03 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -1.099E+05 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -5.233E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -3.067E+04 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 52 FROM -2.318E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 53 FROM -1.605E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 54 FROM -1.011E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 55 FROM -5.155E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 56 FROM -1.014E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 51 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 52 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 53 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 54 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 55 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 56 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 57 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 58 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 59 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 60 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** NEGATIVE DENSITY AT CELL 61 IN FLUID 1. TEMPORARILY SET TO DENOLD

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 51 DENSITY= -1.6951E+01 LIMITER APPLIED

*** WARNING #060 *** DENSITY OUT OF BOUND DUE TO PRESSURE CORRECTION AT CELL 52 DENSITY= -2.6056E-01 LIMITER APPLIED

*** WARNING #007 *** SETTING T AT CELL 50 FROM -5.233E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -3.067E+04 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 52 FROM -2.318E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 53 FROM -1.605E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 54 FROM -1.011E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 55 FROM -5.155E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 56 FROM -1.014E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -5.233E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -3.067E+04 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 52 FROM -2.318E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 53 FROM -1.605E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 54 FROM -1.011E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 55 FROM -5.155E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 56 FROM -1.014E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -5.233E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -3.067E+04 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 52 FROM -2.318E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 53 FROM -1.605E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 54 FROM -1.011E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 55 FROM -5.155E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 56 FROM -1.014E+01 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 50 FROM -5.233E+02 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 51 FROM -3.067E+04 TO 0.01*TREF FOR DENSITY CALCULATION

*** WARNING #007 *** SETTING T AT CELL 52 FROM -2.318E+02 TO 0.01*TREF
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Old   November 12, 2004, 05:05
Default Re: Warning 097-
  #4
matej
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Arnab,

those warnings, are telling you, that the abs. temperature and also density are computetd to be negative. The code reset those values to positive, but such a computation cannot lead to reasonable results. Your case is not well defined, at least numerical paramaters.

If you go in Navigation Center to Analysis controls > Solution Controls >Equation Behavior > Primary Variables you can see 'Differencing schemes' tabs. Here you can set diff. schemes for the case. I'd suggest try first something like upwind. When this is working, you may go for higher order scheme. Enthalpy is represented by Temperature here, for whatever reason.

I guess you would need also some more underrelaxation of temperature and density to stop having those negative.

matej
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Old   November 12, 2004, 12:22
Default Re: Warning 097-
  #5
AB
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Hi Matej and Richard,

All the time I am trying to change the differencing scheme of all the parameters to Upward differencing by using the command 'dsch UD all' but when I see the .run file , no changes are shown and it still takes the CD for some and MARS for some... How can I specify the differencing schemes if it still takes its own. Like it has got mind of its own.

Also how can I change the under relaxation of Density and Temperature? I am not being able to do that.. The run file is attached below.

Will be waiting for comments:

|-------------------------------------------------------------------------------------------|

| ---------------------------- PROBLEM SPECIFICATION SUMMARY ---------------------------- |

|-------------------------------------------------------------------------------------------|

| CASE TITLE .................. => |

| NUMBER OF CELLS ............. => 100 |

| NUMBER OF BOUNDARY FACES .... => 402 |

| MESH DIMENSIONS XMIN XMAX YMIN YMAX ZMIN ZMAX |

| (IN METRES) ............ => 0.0E+00 1.0E+00 0.0E+00 1.0E-02 0.0E+00 1.0E-02 |

| RESTART DATA ................ => WILL BE SAVED ON FILE.pst |

| SURFACE DATA ................ => WILL NOT BE SAVED |

| BOUNDARY DATA ............... => WILL NOT BE PRINTED |

| CONVERGENCE DATA ............ => WILL BE PRINTED ON FILE.info |

| FIELD DATA .................. => WILL NOT BE PRINTED |

| TRANSIENT FLOW (G.RATE)...... => START FROM TIME STEP = 0 |

| HIGHER ORDER CRANK NICHOLSON SCHEME USED |

| (BLENDING FACTOR = 1.000E+00) |

| DATA DUMP (FILE.pst) ........ => EVERY 100 TIME STEPS |

| SOLUTION PROCEDURE .......... => PISO (MAXCOR =100, URFPCOR = 8.000E-01) |

| MAX. NO. OF TIME STEPS ...... => 140 |

| STARTING LOAD STEP NUMBER ... => 1 |

| NUMBER OF TIME STEPS ...... => 140 |

| TIME STEP SIZE ............ => DT = 5.000000E-04 s |

| RAMPING ................... => OFF |

| POST DATA FREQUENCY ....... => 10 |

| CELL DATA SELECTED....... => U, P, T,DEN, H, |

| PRINT DATA FREQUENCY ...... => 0 |

| NO. OF FLUID MATERIALS ...... => 1 |

|-------------------------------------------------------------------------------------------|

|-> FLUID 1 -------------------------------------------------------------------|

|-------------------------------------------------------------------------------------------|

| SOLVE ....................... => U, P, T,DEN, |

| (TOTAL ENTHALPY, THERMAL FORM SOLVED FOR) |

| FLUID FLOW .................. => INVISCID COMPRESSIBLE |

| MONITORING LOCATION ......... => 50 |

| REFERENCE PRESSURE .......... => PREF = 1.000E+05 Pa |

| REFERENCE TEMPERATURE ....... => TREF = 2.730E+02 K |

| DENSITY ..................... => IDEAL GAS: MOLW = 2.896E+01 |

| SPECIFIC HEAT ............... => CONSTANT - C = 1.006E+03 J/kgK |

| CONDUCTIVITY ................ => CONSTANT - K = 1.000E-37 W/mK |

|-------------------------------------------------------------------------------------------|

|-> ADDITIONAL FEATURES USED --------------------------------------------------------------|

|-------------------------------------------------------------------------------------------|

| PLUG AND PLAY |

| RAMFILES OPTION ENABLED |

| TURBO OPTION ENABLED |

|-------------------------------------------------------------------------------------------|

|-> USER FORTRAN CODING USED --------------------------------------------------------------|

|-------------------------------------------------------------------------------------------|

| INITIALISED DEPENDENT VARIABLES |

|-------------------------------------------------------------------------------------------|

|-> BOUNDARY TYPES USED -------------------------------------------------------------------|

|-------------------------------------------------------------------------------------------|

| SYM. PL.,WAVE TR., |

|-------------------------------------------------------------------------------------------|

|-> SOLUTION PARAMETERS -------------------------------------------------------------------|

|-------------------------------------------------------------------------------------------|

| VARIABLE | U V W P TE ED |

|-------------------------------------------------------------------------------------------|

| RELA. FAC. | - - - - - - |

| DIFF. SCH. | CD CD CD - MARS MARS |

| DSCH. FAC. | 1.000E+00 1.000E+00 1.000E+00 - 1.000E+00 1.000E+00 |

| SOLV. TOL. | 1.000E-02 1.000E-02 1.000E-02 1.000E-03 1.000E-02 1.000E-02 |

| SWEEP LIM. | 100 100 100 1000 100 100 |

|-------------------------------------------------------------------------------------------|

| VARIABLE | T DENS TVIS MVIS CP COND |

|-------------------------------------------------------------------------------------------|

| RELA. FAC. | - 1.000E+00 1.000E+00 1.000E+00 1.000E+00 1.000E+00 |

| DIFF. SCH. | CD MARS - |

| DSCH. FAC. | 1.000E+00 - - - - - |

| SOLV. TOL. | 1.000E-02 - - - - - |

| SWEEP LIM. | 100 - - - - - |

|-------------------------------------------------------------------------------------------|

**************************************************

* THERE ARE WARNINGS IN FILE shock.info

**************************************************

|------------------------------------| I--------------------------------------------------| CALCULATION MONITORING INFORMATION |-------------------------------------------I

|------------------------------------|

TIME I------------------- GLOBAL RATE OF CHANGE -----------------I I------------ FIELD VALUES AT MONITORING LOCATION ---------I

STEP UVEL VVEL WVEL MASS T EN DISS ENTH U V W P TE ED T

1 9.00E+01 0.00E+00 0.00E+00 5.09E-03 0.00E+00 0.00E+00 1.21E+04 4.76E+02 0.00E+00 0.00E+00-3.90E+04 0.00E+00 0.00E+00-2.01E+02

2 9.41E+01 0.00E+00 0.00E+00 3.20E-02 0.00E+00 0.00E+00 2.45E+04 -1.74E+02 0.00E+00 0.00E+00-6.13E+04 0.00E+00 0.00E+00 7.99E+01

3 1.73E+02 0.00E+00 0.00E+00 6.21E-02 0.00E+00 0.00E+00 8.95E+04 -1.16E+02 0.00E+00 0.00E+00 6.76E+04 0.00E+00 0.00E+00 3.84E+03

4 2.22E+03 0.00E+00 0.00E+00 1.08E+00 0.00E+00 0.00E+00 1.44E+06 2.43E+03 0.00E+00 0.00E+00 2.77E+05 0.00E+00 0.00E+00 6.07E+04

5 7.47E+04 0.00E+00 0.00E+00 7.25E+11 0.00E+00 0.00E+00 1.61E+19 -6.01E+14 0.00E+00 0.00E+00-1.44E+10 0.00E+00 0.00E+00-1.79E+26 &&&&&& -------------------------------------------------------------- --------------------------------------------------------------

**************************************************

* THERE ARE WARNINGS IN FILE shock.info

**************************************************

*** SOLUTION DIVERGES/UNSTABLE.

*** CALCULATIONS TERMINATED; NEW FILE.div WRITTEN

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Old   November 13, 2004, 08:52
Default Re: Warning 097-
  #6
xhliu1
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the case you are doing is about compressible fluid,and you should use transient analysis,and the time step should be very small. Maybe the problem can solve in this way.
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Old   November 15, 2004, 05:41
Default Re: Warning 097-
  #7
matej
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OK,

you're running transient, therefore you cannot underrelax, as it is nonsense in transient. You have to 'relax' with the time step, as xhliu1 suggests. Try something like 1.0e-6 or less -depends on the problem and phenomena you model.

about the problem with diff. schemes. --sorry for the stupid question, but do you run a geom and prob write after the change? It is usually needed to do a geom write after diff scheme write). Also trying fully implicit may help.

there could be also problem with your user coding. Check the variable limits, not allowing them to shoot away from physical bouds in fortran routine.

matej
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