[wernsen]

Hey guys,

I am having troubles to figure out what the Hf-Value in the thermodynamics is. In the doc of OF:

air 
{ 
    specie 
    { 
        nMoles          1; 
        molWeight       28.96; 
    } 
    thermodynamics 
    { 
        Cp              1004.5; 
        Hf              2.544e+06; 
    } 
    transport 
    { 
        mu              1.8e-05; 
        Pr              0.7; 
    } 
}

so Air has 2.544e+6. The doc says it is the heat of fusion. -> I AM CONFUSED

[Tim.WA]

Bump!

I'm also quite confused about this, all the tutorial examples I can find that are supposedly air have Hf set to 0.

any clues anyone?

[Tim.WA]

Ok think I cracked it for anyone who comes along, Hf is a reference heat of fusion - I was looking in the source code hConstThermoI.h and it's only used to define enthalpy

h = cp*T + Hf

hence only applies with multiple phases or fluid types since h = cp*T generally
therefore if using a single fluid type it doesn't matter what you set it to

please correct me if I'm wrong :-)

[pOverlord]

Originally Posted by Tim.WA

Ok think I cracked it for anyone who comes along, Hf is a reference heat of fusion - I was looking in the source code hConstThermoI.h and it's only used to define enthalpy

h = cp*T + Hf

The specific enthalpy of moist air is



were is the specific enthalpy of dry air (cp*T), is the humidity ratio, and is the specific enthalpy of water vapor.

So, by comparing both expressions, we have that

Hf =

which for dry air should be equal to 0.

[dasa]

Is this the correct explanation?

I noticed Hf=0 for metals. I do not understand how Hf will be related to metals. Can anyone, please explain this?