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UDF for velocity profile

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Old   April 4, 2012, 19:57
Default UDF for velocity profile
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Hi,

I'm trying to write a UDF for an inlet velocity boundary condition. I want my velocity profile varies vertically and transversally. I know how to write a function for each case but not for both at the same time.

x = longitudinal coordinate,
y = vertical coordinate,
z = transversal coordinate.

U(z) = 1.0 + sen((2*pi/750)*z); horizontal velocity as a function of z-coordinate.

U(y) = U(z)*(y/12.8)^0.142857

The center of my channel inlet is at (x,y,z)=(0,0,0), and the contours extent to z = +-175 and y = +-15.

For the vertical velocity profile I wrote the following function:


DEFINE_PROFILE(Velocity, t, i)
{
real x[ND_ND]; /* this will hold the position vector */
real y;
face_t f;
begin_f_loop(f, t) /* loops over all faces in the thread passed
in the DEFINE macro argument */
{
F_CENTROID(x,f,t);
y = x[1];
y = y+15;

F_PROFILE(f, t, i) = 2*pow((y/(12.8)),0.142857);

}
end_f_loop(f, t)
}


But how can I iclude in the function the tranversal variation of velocity???

Any help will be appreciated!!

Regards
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