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August 19, 2005, 17:02 
Normalized residuals

#1 
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I would like to know if the error values for the variables printed out by the program at the monitor window represent the normalized residuals for each variable. If so, is the mass residual normalized by the inlet mass flow rate or not?
Thanks in advance. Sileno 

August 21, 2005, 04:07 
Re: Normalized residuals

#2 
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Hi, Yes the residuals are normalised, however I dont think by inlet values. however they can be normalised by inlet values.
Question:  How do I convert the residuals obtained with SELREF=T to residuals normalised by reference inflow quantities? Answer: This question is best answered by means of an example, which in this case is taken to be 2d singlephase flow in the yz plane with solution for mass continuity (P1), momentum (V1 and W1), enthalpy (H1) and mixture fraction (MIXF). Note that in this example the units of 'resref' and 'res sum' for P1 are kg/s rather than m^3/s because DENPCO=T in the Q1 input file. The conversion procedure is as follows: Near the bottom of the RESULT file you will find the following normalised residuals printout for the last sweep: Wholefield residuals before solution with resref values determined by EARTH & resfac= 1.000E03 variable resref (res sum)/resref P1 3.718E09 1.562E+00 V1 7.078E11 1.819E+02 W1 1.880E08 6.684E01 H1 8.555E03 4.698E01 MIXF 1.317E10 5.908E01 In addition, the following nett source printout is given for all boundary conditions and source terms, including the reference inflow rates of each dependent variable: Nett source of W1 at patch named: INLETF = 1.202E06 Nett source of W1 at patch named: INLETA = 2.238E04 Nett source of W1 at patch named: OUTLET =5.453E04 Nett source of W1 at patch named: WFNN =2.016E04 nett sum=5.219E04 pos. sum= 2.250E04 neg. sum=7.470E04 Nett source of R1 at patch named: INLETF = 2.003E06 Nett source of R1 at patch named: INLETA = 3.799E05 Nett source of R1 at patch named: OUTLET =3.999E05 nett sum=3.638E12 pos. sum= 3.999E05 neg. sum=3.999E05 Nett source of H1 at patch named: INLETF = 9.902E+01 Nett source of H1 at patch named: INLETA = 4.615E+01 Nett source of H1 at patch named: OUTLET =1.452E+02 nett sum= 2.136E04 pos. sum= 1.452E+02 neg. sum=1.452E+02 Nett source of MIXF at patch named: INLETF = 2.003E06 Nett source of MIXF at patch named: OUTLET =2.003E06 nett sum=6.821E13 pos. sum= 2.003E06 neg. sum=2.003E06 The actual residuals can be recovered by multiplying the (resref) column by the (res sum)/resref column, as follows: variable resref (res sum)/resref res sum P1 3.718E09 1.562E+00 5.8075E09 kg/s V1 7.078E11 1.819E+02 1.2875E08 N W1 1.880E08 6.684E01 1.2566E08 N H1 8.555E03 4.698E01 4.0191e03 W MIXF 1.317E10 5.908E01 7.7808E11 kg/s These 'res sum' values can now be normalised by dividing them by the appropriate reference inflow rates (taken from the Nett source printout), as follows: variable ref value res sum %error P1 3.999E05 5.8075E09 kg/s 0.0145 V1 2.250E04 1.2875E08 N 0.0057 W1 2.250E04 1.2566E08 N 0.0056 H1 1.452E+02 4.0191e03 W 0.0028 MIXF 2.003E06 7.7808E11 kg/s 0.0039 

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