[Sergeyevichsky]

Hi all
I want to add velocity fluctuation on inlet by user fortran. Here, thanks Glenn giving me this suggestion. And this is my first time to touch fortran, though I have learned C++ before. After learning fortran roughly, I decide to use the simplest method to generate velocity fluctuations, that is Algebraic methods. The formula is u_i=U_i+r_i*sqrt(2/3*k)， where U_i is mean velocity, r_i is random numbers taken from a normal distribution ℵ(0, 1) of mean µ = 0 and variance σ = 1 and k is kinetic energy. Here is code about random number, but I don't know how to add this code into user fortran. What's more. Which user subroutine should I choose in the shared library? How should I add velocity fluctuations generated by user fortran to 2D plane？
**********************************
Module ran_mod
Implicit None
! ran return a uniform random number between 0-1
! norma return a normal distribution
contains
function ran() !returns random number between 0 - 1
implicit none
integer , save :: flag = 0
double precision :: ran
if(flag==0) then
call random_seed()
flag = 1
endif
call random_number(ran) ! built in fortran 90 random number function
end function ran
function normal(mean,sigma)
implicit none
integer :: flag
double precision, parameter :: pi = 3.141592653589793239
double precision :: u1, u2, y1, y2, normal, mean, sigma
save flag
data flag /0/
u1 = ran(); u2 = ran()
if (flag.eq.0) then
y1 = sqrt(-2.0d0*log(u1))*cos(2.0d0*pi*u2)
normal = mean + sigma*y1
flag = 1
else
y2 = sqrt(-2.0d0*log(u1))*sin(2.0d0*pi*u2)
normal = mean + sigma*y2
endif
end function normal
End Module ran_mod

[ghorrocks]

There are some tutorial examples on CFX user fortran. They are not with the other tutorials (which are on the ANSYS customer webpage), they are in the CFX Modeling Guide, section 18. They are the place to start with fortran in CFX.

[Sergeyevichsky]

Originally Posted by ghorrocks

There are some tutorial examples on CFX user fortran. They are not with the other tutorials (which are on the ANSYS customer webpage), they are in the CFX Modeling Guide, section 18. They are the place to start with fortran in CFX.

Thank you again, Glenn.