[Bill_Yang]

Hi All,

I just found that the description of JANAF method to calculate Cp in the user guide does not match the source coude:

1) version: any version of openfoam since openfoam 8

2) descrption of JANAF method in user guide:
Cp = R*(c0+c1*T+c2*T^2+c3*T^3+c4*T^4)

This method is OK as the predicted value using this equation is very close to ansys fluent.

3) the description of JANAF source code to calculate Cp in the file'OpenFOAM-12/src/thermophysicalModels/specie/thermo/janaf
/janafThermoI.H':

((((a[4]*T + a[3])*T + a[2])*T + a[1])*T + a[0])
+ EquationOfState::Cp(p, T);

4 )I think these two descriptions are totally different.

Could anyone help with this?

Many thanks

[dlahaye]

Pls. look into standard textbook in numerical analysis (Numerical Recipies?) on how to avoid underflow / overflow in evaluating polynomials.

[Bill_Yang]

I don't get your point. Could you please give more details?

Originally Posted by dlahaye

Pls. look into standard textbook in numerical analysis (Numerical Recipies?) on how to avoid underflow / overflow in evaluating polynomials.