[oliveira1820]

Hi everybody!

In my simulation I have 3 fluids, water vapour, liquid water and air. I´m using an energy bulk total source to simulate a proton beam deposition energy into heat.

I want the 18MeV=900W energy to be deposited as the Bethe-Bloch formula: which varies with density and z (depth) position.

How can I truly do this? Depositing the 900 W in its full depth with non uniformal deposition ( dependent of z and density)

[ghorrocks]

I found the Bethe-Bloch equation on wikipedia: https://en.wikipedia.org/wiki/Bethe_formula

Please define non-standard terms in future.

It appears to be a function which evaluates down to a power versus depth in the material. Providing you can derive it down to a function of power versus depth then this will be straight forward to implement as a CEL function.

A second look at your question: I missed that you mention density. How does density come into it? Please show the function you wish to apply.

[oliveira1820]

In the formula, the variable n is dependent of density as you can see on wikipedia right below the formula of Bethe-Bloch.

My doubt is how would be the CEL function for 900W distributed in the same way as the formula describes. Will it be something like this?

Energy= 900 * (constants) * density * z

[ghorrocks]

The wikipedia page defines dE/dx = function(n, beta and others). I have no idea if the equation you quote is correct, that is for you to work out.

But I can say that if the function is of the form E = constants * local density * z then this is easy to implement in CEL. But you cannot define differential equations in CEL, so the wikipedia function cannot be implemented without further derivation.

[oliveira1820]

Thnaks, I get it.

Is it local density a CEL function? Representing the density on a cell or node?

[ghorrocks]

density is just a CEL variable. For the full list of CEL variables, operators and functions look in the CFX reference manual. It has several chapters on CEL and variables.

[oliveira1820]

I just thought you were distinguishing between density and local density

[ghorrocks]

I should have clarified it a bit I guess. I was trying to distinguish the field variable, density, from things like line, area or volume averaged density; or density somewhere else. By local density I was meaning the density at that location.

[oliveira1820]

Thank you very much