[adsl17754]

Hi, all

I encountered a problem when I tried FLUENT13.0 to simualte a premix combustion problem, I imported a chemical mechanism from CHEMKIN (30 species and 50 reactions). When FLUENT started calculation, a warning "Truncation Error > Truncation error tolerance" always occured, even when the iteration time step size was reduced to 1e-10s. I don't think the iteration time step size needs to be that small. The mechanism I used was erc_nhep ( listed below), any suggestion is welcome.

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erc_nhep mechanism:

elements
h c o n
end

species
nc7h16 o2 co2 h2o co h2 oh h2o2 ho2 h o
ch3o ch2o hco ch2 ch3 ch4 c2h3 c2h4 c2h5 c3h4 c3h5 c3h6 c3h7
c7h15-2 c7h15o2 c7ket12 c5h11co n2
end

reactions
nc7h16 + h = c7h15-2 + h2 4.380e+07 2.0 4760.0
nc7h16 + oh = c7h15-2 + h2o 9.700e+09 1.3 1690.0
nc7h16 + ho2 = c7h15-2 + h2o2 1.650e+13 0.0 16950.0
nc7h16 + o2 = c7h15-2 + ho2 2.000e+15 0.0 47380.0
c7h15-2 + o2 = c7h15o2 1.560e+12 0.0 0.0
c7h15o2 + o2 = c7ket12 + oh 4.500E+14 0.0 18232.712
c7ket12 = c5h11co + ch2o + oh 9.530e+14 0.0 4.110e+4
c5h11co = c2h4 + c3h7 + co 9.84E+15 0.0 4.02E+04
c7h15-2 = c2h5 + c2h4 + c3h6 7.045E+14 0.0 3.46E+04
c3h7 = c2h4 + ch3 9.600e+13 0.0 30950.0
c3h7 = c3h6 + h 1.250e+14 0.0 36900.0
c3h6 + ch3 = c3h5 + ch4 9.000e+12 0.0 8480.0
c3h5 + o2 = c3h4 + ho2 6.000e+11 0.0 10000.0
c3h4 + oh = c2h3 + ch2o 1.000e+12 0.0 0.0
c3h4 + oh = c2h4 + hco 1.000e+12 0.0 0.0
ch3 + ho2 = ch3o + oh 5.000e+13 0.00 0.
ch3 + oh = ch2 + h2o 7.500e+06 2.00 5000.
ch2 + oh = ch2o + h 2.500e+13 0.00 0.
ch2 + o2 = hco + oh 4.300e+10 0.00 -500.
ch2 + o2 = co2 + h2 6.900e+11 0.00 500.
ch2 + o2 = co + h2o 2.000e+10 0.00 -1000.
ch2 + o2 = ch2o + o 5.000e+13 0.00 9000.
ch2 + o2 = co2 + h + h 1.600e+12 0.00 1000.
ch2 + o2 = co + oh + h 8.600e+10 0.00 -500.
ch3o + co = ch3 + co2 1.570e+14 0.00 11800.
co + oh = co2 + h 8.987e+07 1.38 5232.877
o + oh = o2 + h 4.000e+14 -0.50 0.
h + ho2 = oh + oh 1.700e+14 0.0 875.
oh + oh = o + h2o 6.000e+08 1.30 0.
h + o2 + m = ho2 + m 3.600e+17 -0.72 0.
h2o/21./ co2/5.0/ h2/3.3/ co/2.0/
h2o2 + m = oh + oh + m 1.000e+16 0.00 45500.
h2o/21./ co2/5.0/ h2/3.3/ co/2.0/
h2 + oh = h2o + h 1.170e+09 1.30 3626.
ho2 + ho2 = h2o2 + o2 3.000e+12 0.00 0.
ch2o + oh = hco + h2o 5.563e+10 1.095 -76.517
ch2o + ho2 = hco + h2o2 3.000e+12 0.00 8000.
hco + o2 = ho2 + co 3.300e+13 -0.40 0.
hco + m = h + co + m 1.591E+18 0.95 56712.329
ch3 + ch3o = ch4 + ch2o 4.300e+14 0.00 0.
c2h4 + oh = ch2o + ch3 6.000e+13 0.0 960.
c2h4 + oh = c2h3 + h2o 8.020e+13 0.00 5955.
c2h3 + o2 = ch2o + hco 4.000e+12 0.00 -250.
c2h3 + hco = c2h4 + co 6.034e+13 0.0 0.
c2h5 + o2 = c2h4 + ho2 2.000e+10 0.0 -2200.
ch4 + o2 = ch3 + ho2 7.900e+13 0.00 56000.
oh + ho2 = h2o + o2 7.50E+12 0.0 0.
ch3 + o2 = ch2o + oh 3.80E+11 0.0 9000.
ch4 + h = ch3 + h2 6.600e+08 1.60 10840.
ch4 + oh = ch3 + h2o 1.600e+06 2.10 2460.
ch4 + o = ch3 + oh 1.020e+09 1.50 8604.
ch4 + ho2 = ch3 + h2o2 9.000e+11 0.00 18700.
ch4 + ch2 = ch3 + ch3 4.000e+12 0.00 -570.
c3h6 = c2h3 + ch3 3.150e+15 0.0 85500.0
end