Hi, I was going through the discussion in between you at cfx user's forum on NLTE(NON LOCAL THERMAL EQ.).Since i am also working in heat and mass transfer through porous media,i thought you will be the right person to contact.My problem goes like this:- In a cylindrical container porous solid is filled and a gas is passed though it via a disc type filter at the inlet.and the reaction is taking place which is exothermic.so it is dipped in an constant temperature bath to take away that heat to sustain that reaction.So for this i am supposed to solve(1)two energy equation(2) two mass balance(for solid/fluid)(3)reaction rate equation of arrhenius type but the pre exponential factor is not constant,its an expression and is a function of pressure and concentration.and the source term for energy is the product of heat of reaction and reaction rate,mass balance source term is reaction rate expression.So i want to know whether this is possible in CFX or NOT?????????????????

thanks in advance, prompt reply will be appreciated

ARVIND

Hi Arvind,

It is possible to do what you are asking by formulating an additional variable as a temperature or enthalpy equation specific to a domain and adding appropriate source/sink pairs between the "solid" thermal equation and the fluid one. Similarly you could make the reaction rate a function of another variable.

Regards, Robin

Hi Robin,

Thanks for the reply,right now i am trying my problem in fluent.what i further want to know is,how is the udf/uds defining procedure in CFX.Is it complicated or easy bcoz i havent worked in fortan till now.Since in fluent they are defining it with the help of C and their own defined macros and i know C a bit.so i am feeling comfortable with fluent but i simultaneously want to try it on CFX too.Plz guide me in this regard.

Arvind

Hi Arvind,

CFX does not require any user subroutines for the vast majority of modifications. Rather, it has an algebraic expression language known as the CFX Expression Language or CEL. CEL allows you to insert equations in place of static values. For instance, an equation for velocity as a funtion of radius, or a source term which varies based on a mass flow averaged quantity at an outlet.

If more complicated logic is requires, user can create their own CEL functions by linking a Fortran subroutine. There are also Fortran routines for modifying other aspects of the solver. Most likely, you will need neither of these for your application.

Regards, Robin

Hi Robin,

Thanks for the guidance,if you dont mind can i have your mail id.

Regards Arvind

Sorry Arvind, but I don't give out my email address on this forum.

Hi Robin,

Then send it on my personal mail id arvind_phate@yahoo.co.in.Will this be okay.Waiting for your reply. Arvind Phate