[alikhan]

hi
im trying to create a tornado ,so i write audf for simulating the tornado but i cant set the angle between two radial and tangential velocities in cylinderical domain which has the inlet in half of the body .in tornado i need swirling ratio .it's equation is s=tantetha/2a that 2a has a constant value but i dont have thetha , so by this udf that i have i should have s=.5 but i cant set thetha a canstant thetha to reach .5 in value beacase i dont have thetha can u correct my udf im really need it for my thesis



/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_radial_velocity, thread, position)
{
real x[ND_ND]; /* this will hold the position vector */
real z;
face_t f;

begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
F_PROFILE(f,thread,position)= 10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_tangential_velocity, thread, position)
{
real x[ND_ND],theta; /* this will hold the position vector */
real z;
face_t f;
begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
theta=atan(x[1]/x[0]);
F_PROFILE(f,thread,position)= 2.*1.0176*(tan(theta)/2.05)*10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

[pakk]

Originally Posted by alikhan

...it's equation is s=tantetha/2a that 2a has a constant value but i dont have thetha , so by this udf that i have i should have s=.5 but i cant set thetha a canstant thetha to reach .5 in value beacase i dont have thetha ...

I try to find out what you are asking... It looks like you want to set theta, but you can not find theta in your code...

...
theta=atan(x[1]/x[0]);
...

Found it! Does this solve your problem? If not, be clear about what you want, because then I have no idea what you are asking...

[alikhan]

Boundary conditions for tornado simulator and bluff-body
At the inlet, the flow velocity has two components (radial and tangential) in order to
produce the swirling flow field. The radial and tangential velocity components are given
by equations (1) and (2), respectively.

1=V1*(z/z1)^1/7 2=Vt=2H0/R0*S*Vr i have the value of V1=10m/s ,Z1=106m,2H0/R0=2*1.0176,s=tantheta/2.05 that S should have value equal to 0.5 thetha is un known i set it constant like 45 degree once another time in radian but nothing happen

[alikhan]

Capture1.JPGCapture.JPGCapture2.JPGCapture3.JPGCapture4.JPG

[alikhan]

Originally Posted by pakk

I try to find out what you are asking... It looks like you want to set theta, but you can not find theta in your code...

Found it! Does this solve your problem? If not, be clear about what you want, because then I have no idea what you are asking...

thank you so much i give you some information may be it help you to understand my problem pleasr read my replies

[pakk]

Copied from your code:

theta=atan(x[1]/x[0]);
F_PROFILE(f,thread,position)= 2.*1.0176*(tan(theta)/2.05)*10.*pow((z/106.),1./7.);

For simplicity, let's define S and a:

theta=atan(x[1]/x[0]);
a=1.025;
S=tan(theta)/(2*a);
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

I did nothing until now, just rephrasing your code.

And now you want to use a different definition for S, namely S=0.5.

theta=atan(x[1]/x[0]);
a=1.025;
S=0.5;
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

Let's combine everything, and remove unnecessary definitions:

F_PROFILE(f,thread,position)= 2.*1.0176*0.5*10.*pow((z/106.),1./7.);

Is this what you want?

[alikhan]

Originally Posted by pakk

Copied from your code:

theta=atan(x[1]/x[0]);
F_PROFILE(f,thread,position)= 2.*1.0176*(tan(theta)/2.05)*10.*pow((z/106.),1./7.);

For simplicity, let's define S and a:

theta=atan(x[1]/x[0]);
a=1.025;
S=tan(theta)/(2*a);
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

I did nothing until now, just rephrasing your code.

And now you want to use a different definition for S, namely S=0.5.

theta=atan(x[1]/x[0]);
a=1.025;
S=0.5;
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

Let's combine everything, and remove unnecessary definitions:

F_PROFILE(f,thread,position)= 2.*1.0176*0.5*10.*pow((z/106.),1./7.);

Is this what you want?

thank you so much is there a lot of difference between my code and this correction you made i want to know why?

[alikhan]

/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_radial_velocity, thread, position)
{
real x[ND_ND]; /* this will hold the position vector */
real z;
face_t f;

begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
F_PROFILE(f,thread,position)= 10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_tangential_velocity, thread, position)
{
real x[ND_ND],theta; /* this will hold the position vector */
real z;
face_t f;
begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
theta=atan(x[1]/x[0]);
a=1.025;
S=0.5;
S=tan(theta/2*a);
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

[pakk]

Originally Posted by alikhan

thank you so much is there a lot of difference between my code and this correction you made i want to know why?

If you want to know why: read my post. I did my best to explain it, I am not going to repeat myself. If you have specific questions, come back.

[pakk]

Originally Posted by alikhan

/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_radial_velocity, thread, position)
{
real x[ND_ND]; /* this will hold the position vector */
real z;
face_t f;

begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
F_PROFILE(f,thread,position)= 10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

/************************************************** ***********************/
/* vprofile.c */
/* UDF for specifying a steady-state velocity profile boundary condition */
/************************************************** ***********************/

#include "udf.h"

DEFINE_PROFILE(inlet_tangential_velocity, thread, position)
{
real x[ND_ND],theta; /* this will hold the position vector */
real z;
face_t f;
begin_f_loop(f,thread)
{
F_CENTROID(x,f,thread);
z = x[2];
theta=atan(x[1]/x[0]);
a=1.025;
S=0.5;
S=tan(theta/2*a);
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);
}
end_f_loop(f,thread)
}

This is of course not ok. Because you are not careful about what you replaced. Be more careful! Details matter!

[alikhan]

Originally Posted by pakk

This is of course not ok. Because you are not careful about what you replaced. Be more careful! Details matter!

thank you so much i try my best to make it . have nice day

[alikhan]

Originally Posted by pakk

Copied from your code:

theta=atan(x[1]/x[0]);
F_PROFILE(f,thread,position)= 2.*1.0176*(tan(theta)/2.05)*10.*pow((z/106.),1./7.);

For simplicity, let's define S and a:

theta=atan(x[1]/x[0]);
a=1.025;
S=tan(theta)/(2*a);
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

I did nothing until now, just rephrasing your code.

And now you want to use a different definition for S, namely S=0.5.

theta=atan(x[1]/x[0]);
a=1.025;
S=0.5;
F_PROFILE(f,thread,position)= 2.*1.0176*S*10.*pow((z/106.),1./7.);

Let's combine everything, and remove unnecessary definitions:

F_PROFILE(f,thread,position)= 2.*1.0176*0.5*10.*pow((z/106.),1./7.);

Is this what you want?

i dont know how to apply both s=0.5 and s= tan(theta)/2a at the same time itry alot but i'm really weak in programming and udf

[pakk]

Originally Posted by alikhan

i dont know how to apply both s=0.5 and s= tan(theta)/2a at the same time itry alot but i'm really weak in programming and udf

s=0.5 and s=tan(theta)/2a means tan(theta)/2a=0.5

So if s=0.5, you don't have to set theta anymore... That is what I did above.