# turbFoam floating point exception and k-epsilon

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 April 28, 2009, 04:10 #2 Senior Member   Rishi . Join Date: Mar 2009 Posts: 149 Rep Power: 17 Hi, My guess is that your deltaT is very large ! Courant Number mean: 5.18024e+43 max: 4.56829e+47 and time step continuity errors : sum local = 2.17993e+170, global = -1.77391e+136, cumulative = -1.77391e+136 I would suggest to check your log file and check the Courant number from first time step. If its increasing exponentially( my guess), then use 1/10th of current delta t till you get Courant number near 1 or less. Courant number should be below 1. Hope this helps Rishi

 April 28, 2009, 04:20 #3 New Member   Join Date: Mar 2009 Posts: 28 Rep Power: 17 Thanks for the really quick answer. I will decrease my timesteps...and look up Courant number

 April 28, 2009, 05:10 #4 New Member   Join Date: Mar 2009 Posts: 28 Rep Power: 17 Still the same problem. I am trying the solve it with adjustable deltaT as described by niklas in this forum

 April 28, 2009, 07:10 #5 Senior Member   Gavin Tabor Join Date: Mar 2009 Posts: 181 Rep Power: 17 Looks to me like you have a divergence problem with your solution; you are unlikely to solve this by adjusting the timestep (particularly by the time you get to a courant number e+47! Go back through the log file and see if you can identify which equation is having the problem at the start (you might notice that one of the equations is not converging, or stops converging, or suddenly requires 500 iterations to converge where it used to need 50). Is the mesh strongly non-orthogonal? If so, generate a better one or increase the non-orthogonality corrections. Try running with upwind differencing on the div term for a bit, or use simpleFoam to start the solution off. Gavin