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May 18, 2010, 07:28 
Fatal Bound Error

#1 
New Member
Arun
Join Date: Apr 2010
Posts: 8
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I am trying to do heat transfer analysis so i have introduced negative heat flux on the surface from 1000 to 100000 but when i give greater than 110000 heat flux value it converged but while writing the output it shows error as below
Locale : WALL Variable : Density Writing crash recovery file ERROR #001100279 has occurred in subroutine ErrAction. Message: Stopped in routine ENFORCE_BOUNDS An error has occurred in cfx5solve: The ANSYS CFX solver exited with return code 1. No results file has been created. End of solution stage. 

May 18, 2010, 07:51 

#2 
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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Looks like an error where the bounds of density were exceeded and it probably ended up with either a huge or negative density. Are you sure the simulation converged?


May 18, 2010, 10:14 

#3 
Member
Luis Filipe Fabiani
Join Date: Apr 2009
Posts: 43
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arunss,
Try checking the variable range information (on the OUT file), especifically the density part. It sounds like the density is way off the scale, and it generates this error. 

May 18, 2010, 12:38 

#4  
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Arun
Join Date: Apr 2010
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Quote:
I tried with variable range information while stating the density value is 3.9 at the point where it converged the value is 4.3 there is no much change in the density. i tried by doing backup for every 25 iteration but it save till 100 iteration at 125 iteration it shows the same error(actually it converged at 230 iteration) 

May 18, 2010, 12:54 

#5 
Member
Luis Filipe Fabiani
Join Date: Apr 2009
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arunss,
On "expert parameters", "I/O Control", enable the "monitor ranges" option (set it to "t" as in TRUE) Check the iteration where the solver gives the error, and check the "Variable Range Information" table that will be available on your OUT file What's the min and max value of density? 

May 18, 2010, 13:05 

#6  
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Arun
Join Date: Apr 2010
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Quote:
++  Writing backup file 100_full.bak   Name : Backup Results 1   Type : Standard   Option : Iteration Interval  ++ ++  Average Scale Information  ++ Domain Name : Domain 1 Global Length = 1.2495E01 Minimum Extent = 1.1299E01 Maximum Extent = 1.0000E+00 Density = 4.2201E+00 Dynamic Viscosity = 1.0000E05 Velocity = 2.3687E+01 Advection Time = 5.2749E03 Reynolds Number = 1.2490E+06 Speed of Sound = 8.5287E+02 Mach Number = 2.7774E02 Thermal Conductivity = 1.0000E02 Specific Heat Capacity at Constant Pressure = 1.2091E+03 Specific Heat Capacity at Constant Volume = 9.0904E+02 Specific Heat Ratio = 1.3301E+00 Prandtl Number = 1.2091E+00 Temperature Range = 4.5251E+02 ++  Average Scale Information  ++ For 125 iteration Domain Name : Domain 1 Global Length = 1.2495E01 Minimum Extent = 1.1299E01 Maximum Extent = 1.0000E+00 Density = 4.2127E+00 Dynamic Viscosity = 1.0000E05 Velocity = 2.3960E+01 Advection Time = 5.2149E03 Reynolds Number = 1.2612E+06 Speed of Sound = 8.5365E+02 Mach Number = 2.8068E02 Thermal Conductivity = 1.0000E02 Specific Heat Capacity at Constant Pressure = 1.2091E+03 Specific Heat Capacity at Constant Volume = 9.0904E+02 Specific Heat Ratio = 1.3301E+00 Prandtl Number = 1.2091E+00 Temperature Range = 4.4423E+02 Locale : WALL it shows error 

May 18, 2010, 13:11 

#7 
Member
Luis Filipe Fabiani
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Check for something like:
++  Variable Range Information  ++ Domain Name : Domain 1 ++  Variable Name  min  max  ++  Density  1.88E01  8.00E01   Specific Heat Capacity at Constant Pressure 1.27E+03  2.21E+03   Dynamic Viscosity  1.11E05  1.68E05   Thermal Conductivity  2.12E02  3.43E02   Isothermal Compressibility  9.84E06  9.91E06   Static Entropy  8.03E+03  1.16E+04   N2.Density  1.66E01  1.13E+00   N2.Specific Heat Capacity at Constant Press 1.04E+03  1.29E+03   N2.Dynamic Viscosity  1.77E05  1.77E05  + 

May 19, 2010, 06:16 

#8  
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Arun
Join Date: Apr 2010
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Quote:
For iteration 1 ++  Variable Range Information  ++ Domain Name : Domain 1 ++  Variable Name  min  max  ++  Density  3.83E+00  3.96E+00   Specific Heat Capacity at Constant Pressure 1.21E+03  1.21E+03   Dynamic Viscosity  1.00E05  1.00E05   Thermal Conductivity  1.00E02  1.00E02   Isothermal Compressibility  4.34E07  4.35E07   Static Entropy  1.32E+03  1.36E+03   Velocity u  2.67E01  7.44E+00   Velocity v  1.49E+00  1.44E+00   Velocity w  1.56E+00  1.59E+00   Pressure  2.20E+06  2.20E+06   Turbulence Kinetic Energy  1.01E03  2.51E02   Turbulence Eddy Dissipation  3.55E03  3.75E01   Eddy Viscosity  4.55E05  1.61E03   Temperature  1.94E+03  2.00E+03   Static Enthalpy  1.98E+06  2.06E+06  ++ For 100th iteration ++  Variable Range Information  ++ Domain Name : Domain 1 ++  Variable Name  min  max  ++  Density  3.57E+00  4.96E+00   Specific Heat Capacity at Constant Pressure 1.21E+03  1.21E+03   Dynamic Viscosity  1.00E05  1.00E05   Thermal Conductivity  1.00E02  1.00E02   Isothermal Compressibility  4.24E07  4.67E07   Static Entropy  1.05E+03  1.39E+03   Velocity u  2.29E+01  2.97E+02   Velocity v  6.55E+01  5.79E+01   Velocity w  7.61E+01  7.43E+01   Pressure  2.04E+06  2.26E+06   Turbulence Kinetic Energy  8.92E04  2.76E+02   Turbulence Eddy Dissipation  2.75E03  2.05E+07   Eddy Viscosity  1.68E05  8.90E03   Temperature  1.55E+03  2.00E+03   Static Enthalpy  1.51E+06  2.06E+06  ++ After converged at 220 iteration ++  Variable Name  min  max  ++  Density  3.55E+00  4.95E+00   Specific Heat Capacity at Constant Pressure 1.21E+03  1.21E+03   Dynamic Viscosity  1.00E05  1.00E05   Thermal Conductivity  1.00E02  1.00E02   Isothermal Compressibility  4.24E07  4.69E07   Static Entropy  1.06E+03  1.39E+03   Velocity u  2.38E+01  3.04E+02   Velocity v  6.68E+01  5.91E+01   Velocity w  7.76E+01  7.86E+01   Pressure  2.03E+06  2.26E+06   Turbulence Kinetic Energy  7.95E04  2.87E+02   Turbulence Eddy Dissipation  2.31E03  2.18E+07   Eddy Viscosity  1.22E05  4.68E03   Temperature  1.55E+03  2.00E+03   Static Enthalpy  1.51E+06  2.06E+06  ++ Fatal bounds error detected  Variable: Density Locale : WALL ++  Writing crash recovery file  ++ ++  ERROR #001100279 has occurred in subroutine ErrAction.   Message:   Stopped in routine ENFORCE_BOUNDS            ++ ++  An error has occurred in cfx5solve:     The ANSYS CFX solver exited with return code 1. No results file   has been created.  ++ End of solution stage. ++  Warning!     The ANSYS CFX Solver has written a crash recovery file. This file   has been saved as C:\Documents and Settings\Arun Kumar\Desktop\27   April Home\GG_012.res.err and may be an aid to diagnosing the   problem or restarting the run. More details should be available   in the solver output section of the output file.  ++ 

May 20, 2010, 11:59 

#9 
Member
Luis Filipe Fabiani
Join Date: Apr 2009
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Aruns,
The only strange thing is the pressure: 2.26E+06 Pa is 22 bar... does this correspond to what you are trying to simulate? Can you give a brief description of the problem? Best regards 

May 21, 2010, 11:51 

#10  
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Arun
Join Date: Apr 2010
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Quote:
I try to simulate gas generator system, which meas it store the gas with high temperature about 2000K and pressure about 23 bar in the chamber and it passes through converged diverged nozzle and exit via two pipes. the exit condition is pressure 22 bar, mass flow rate 6.5 gms/ sec and temperature 1273K, To reduce the temperature of the gas i introduced heat flux on wall (without heat flux the temperature is 2000K), i uploaded the geometry of the model the link has been given below http://www.loadmypicture.com/getimag...2344397362.jpg Total Size is about 0.5m length Chamber dia 115mm and length is 150mm and it converged to dia 5 mm and length of converged section is 75mm and diverged section end diameter is 12.7mm and length 75 mm and two pipes are connected 

May 21, 2010, 12:51 

#11 
Member
Luis Filipe Fabiani
Join Date: Apr 2009
Posts: 43
Rep Power: 9 
Arun,
In which walls are you trying to set the heat flux? If this wall is too small, there will be a lot of heat exchange going on a very small area, and this could cause numerical errors. 

May 22, 2010, 03:27 

#12  
New Member
Arun
Join Date: Apr 2010
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Quote:
So i increase the pipe length from 300mm to 700mm still i am getting the same error 

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