[CFDJonas]

Hello,

I have a problem with my UDF calculating the specific heat Cp for my mixture. Even if I take the simple example given in the manual (see below) I get an error. The initialization works fine (the Message within the UDF delivers the correct cp during initialization, also enthalpy h is not null). But when I start the simulation following error appears for every node:

Error at Node X: Non-physical Specific Heat = 0.000000e+00

DEFINE_SPECIFIC_HEAT(heat_capacity, T, Tref, h, yi)
{
	// Enthalpy must be set (requirement for this udf-macro by Fluent)
        real cp = 2000.0;
	*h = cp * (T - Tref);
	Message("\n T = %f\tyi_specie0 = %f\tcp = %f\th = %f\tT_ref = %f", T, yi[0], cp, *h, Tref);
	return cp;
}

I am using Ansys Fluent 19.2.

Another question: Why does SV_SpeciesIndex(.., ..) now needs two arguments instead of one? I used to get the index via SV_SpeciesIndex("specie0") in earlier version but somehow this isn't working anymore in 19.2.

Thank you for your help!

EDIT: Additional information: The error only occurs when I have volumetric reaction turned on, even though the mechanism is empty/the fluid phase "reaction" check box is NOT selected. Just the activated volumetric reaction model leads to getting this error. Somehow this changes the calculation of cp?