Learning Forum

[surajgarad]

Hi,

I need combined heave and pitch motion in fluent. I gone through some of the UDF's available over the internet and also the Ansys UDF manual. Based on that I have written / modified UDF. Now the problem which I am facing is when I am giving phase difference, I am getting the combined motion properly but when I removed phase difference, the motion which I am getting is somewhat different. Prior to combined motions, I have checked UDF for individual heave and pitch motions and it works well.

As per knowledge, there is no concept of phase difference between heave and pitch motions and it should not be mandatory to mention in the UDF. I have also checked by changing center of gravity location as pitch motion will be about C.G. of the body.

#include "udf.h"

DEFINE_CG_MOTION(airfoil, dt, vel, omega, time, dtime)

{

real a, w, p, b, pi;

pi = 3.14159265;

/* define motion variables */

a = 1; /* pitch Amplitude */

b = 0.5;   /*heave amplitude */

w = 2 * pi *1.06; /*Angular Frequency*/

p = pi / 2; /*Phase*/

/* define airfoil motion */

vel[1] = b*sin(w*time); /*heave motion*/

omega[2] = a*sin(w*time + p); /* z-component of angular velocity */

}

[Rahul Kumar]

Hello, 

What is the motion that you are getting without phase difference? Also, please make sure the setup of the problem is right.