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IDProjectCategoryView StatusLast Update
0000385freesteamnumerical-routinespublic2008-11-18 10:17
Reporterjohn 
Assigned Tojohn 
PrioritynormalSeverityminorReproducibilityalways
Status resolvedResolutionfixed 
Product Version 
Target VersionFixed in Version 
Summary0000385: Error in phirdeltadelta equation: position of brackets
DescriptionHi John,

I think I found a typo in the iapws95.cpp file. In the function
phirdeltadelta, a parenthesis is badly placed. Instead of:

           Num d2Deltaddelta2 = 1/d1*dDeltaddelta + d1*d1*(4*B[i]*a[i]*
                (a[i]-1)*pow(d1*d1, a[i]-2) + 2*A[i]*A[i]*
                (1/(beta[i]*beta[i]))*a1*a1) +
                A[i]*theta*4/beta[i]*(1/(2*beta[i]) - 1)*
                pow(d1*d1, 1/(2*beta[i]) - 2);

one should have:

           Num d2Deltaddelta2 = 1/d1*dDeltaddelta + d1*d1*(4*B[i]*a[i]*
                (a[i]-1)*pow(d1*d1, a[i]-2) + 2*A[i]*A[i]*
                (1/(beta[i]*beta[i]))*a1*a1 +
                A[i]*theta*4/beta[i]*(1/(2*beta[i]) - 1)*
                pow(d1*d1, 1/(2*beta[i]) - 2));

This typo explains a too large error in the computation of cp and w.
Best regards,

Laurent
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john

2008-11-18 10:16

administrator   ~0000484

fixed in changeset freesteam 457

Issue History

Date Modified Username Field Change
2008-11-18 10:16 john New Issue
2008-11-18 10:16 john Note Added: 0000484
2008-11-18 10:17 john Status new => resolved
2008-11-18 10:17 john Resolution open => fixed
2008-11-18 10:17 john Assigned To => john