[h.mortezaee]

hi all
i font know how to define a udf that describe a energy deposition in gas from proton beam penetration , the formula that gives the energy deposition is dE/Dx=f(...) , i really need some help , i really appreciate it , and if its quick it will be awesome ,
im new to udf concept .

[Sun]

Could you please firstly write down the entire equation for the energy deposition and describe each terms in that equation.
Second, can you provide some details on what you are simulating.
Then, i might be able to help you.
Cheers!

[h.mortezaee]

im gonna simulate natural convection inside a cylindrical enclosure , the formula is dE/dX=4π/(m_e c^2 )∙(nz^2)/β^2 ∙(e^2/(4πε_0 ))^2∙[ln((2m_e c^2 β^2)/(I∙(1-β^2 ) ))-β^2 ]
, this is the bethe-bloch formula , energy per distance that proton go through the matter is a function of proton energy and other parameters like gas atomic number and etc , the protons deposit their energy along their path , and lose their energy and when their energy get to the certain point the energy deposition will be much larger , its just to describe the physics of the proton penetration , there is some relativity terms that are not a concern , there is codes to calculate the beam scattering and energy deposition per cell of the mesh , the codes give a database that every cell get a portion of energy , i need to make fluent read from the database and calculate the stream inside the enclosure , first i was going to develop cfd code from scratch but it seems to be a really hard work to do then i thought fluent will be easier , if further info is required i can give tell me , thank you for the reply ,
it mean so much

[Sun]

Thanks for the explanation. I am not really expert on the field you are working. But, I've just had a look at this page and fairly get the hang of equations.
Correct me if I am wrong, you have a transport equation for E which has a source term on the right hand side. The E only changes by the spatial location and NOT time, right? and there is no diffusion?

I think you can define a steady state "User Defined Scalar" (or UDS) in fluent with a source term. The source term should to be coded in an UDF via DEFINE_SOURCE macro.

In the source term or the RHS of dE/dx, is there any parameters that change with the location? If not, your life would be much more easier!

there is codes to calculate the beam scattering and energy deposition per cell of the mesh , the codes give a database that every cell get a portion of energy , i need to make fluent read from the database and calculate the stream inside the enclosure

and the last point, how do you plan to read the database of E in fluent? are you thinking about initializing your domain with the values you get from the other codes?
cheers!