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-   -   Error Object: nan (http://www.cfd-online.com/Forums/fluent/37351-error-object-nan.html)

Kajal Mehta July 22, 2005 18:59

Error Object: nan
 
Hi all,

I get an error (plz see below) while solving a steady-state natural convection simulation.

Error: > (greater-than): invalid argument [2]: wrong type [not a number] Error Object: nan

Does this error look familiar to someone? Any guidance is much appreciated!

Thanks, Kajal Mehta

Saurav July 22, 2005 23:06

Re: Error Object: nan
 
Well ball park answer, ur mass momentum and energy eqns. are all diverging. As u haven't mentioned anything about what u r solving for, can't comment anything further...by the way one guess...under relax ur equations...might still get NAN but not as soon as u might be getting right now....

Saurav

Mahesh July 23, 2005 00:28

Re: Error Object: nan
 
Can u mention, what r u solving for?

Swarup July 23, 2005 05:19

Re: Error Object: nan
 
Check your input boxes. Although I am not sure about this, I think you have not written a number properly or you have mentioned something very much larger/smaller than allowed. the solver is ultimately ending up with 0/0 or inf/inf; hence the message. Swarup

Mohamed HENDAWI August 1, 2005 12:13

Re: Error Object: nan
 
Hi I receive the same error (see below plz) I'm modelizing a water droplet jet with evaporation (DPM model, unsteady solver, k e tubulence model ).

The computaion seemed converging correctly until about 6000 iteration (time =0.91 s with time step=0.01s) and 1262 of tracked particles (by injection of 20 per time step). Then I receive the same error!!!

Any idea? Thaks in Advance Mohamed

PS: error message (at the end):

Updating solution at time level N... done.

start time:0.000000e+00s, stop time: 1.000000e+01s, time:9.299999e-01s time step:9.999990e-03s

DPM Iteration .... Time of the Day : Hour =13 Min=0

start time:0.000000e+00s, stop time: 1.000000e+01s, time:9.299999e-01s time step:9.999990e-03s

start time:0.000000e+00s, stop time: 1.000000e+01s, time:9.299999e-01s time step:9.999990e-03s Injecting 20 particles at t = 0.93 number tracked = 1302, escaped = 0, aborted = 0, trapped = 0, evaporated = 16, incomplete = 0, coalesced = 0, shed = 7 Parallel particle tracking concurrency: 0%

iter continuity x-velocity y-velocity z-velocity energy k epsilon h2o vm_s vm_y time/iter

Error: > (greater-than): invalid argument [2]: wrong type [not a number] Error Object: nan

Swarup August 1, 2005 12:49

Re: Error Object: nan
 
Hi Mohammed, are you sure that none of the residuals is going out of control? Ultimate reason for such an error is an undefined quantity. This is happening after a lot of iterations. I guess errors in calculation of some quantity are building up slowly till that time and then there is blow-up. I am unable to pin-point the source and can give you some hints. You should check whether any region of your computational domain experiences lot of changes in a short time and how fine/appropriate your grid is in that region. To be sure, you may review all your inputs and boundary conditions. Please check with Fluent support team if problem is still persisting.

Best Of Luck.

Swarup.


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