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Simulating a flapping airfoil by Fluent which the phase difference equals to 90

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Old   September 20, 2018, 04:49
Default Simulating a flapping airfoil by Fluent which the phase difference equals to 90
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Hanye Azimi
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Hi
I'm simulating a flapping airfoil(Naca0015) by AnsysFluent

How can I model a flapping motion which the phase difference between pitching and heaving is not zero? I used this UDF for flapping motion while phase difference equals to zero:


#include "udf.h"
DEFINE_CG_MOTION(plunge,dt,vel,omega,time,dtime)
{
Thread *t;
face_t f;
real w,a, pi;
pi = 3.14159265;
a = (pi*15)/180; /*pitch amplitude*/
w = 1.168; /*angular velocity*/


/*defining the flapping motion*/
vel[1] = 0.5*w*cos(w*time); /*Heaving motion*/
omega[2]=a*w*cos(w*time); /*pitching motion*/
} It's OK!





I tried the followed UDF for the case which phase difference is 90 :


#include "udf.h"
DEFINE_CG_MOTION(plunge,dt,vel,omega,time,dtime)
{
Thread *t;
face_t f;
real w,a, pi,fi;
pi = 3.14159265;
a = (pi*15)/180; /*pitch amplitude*/
w = 1.168; /*angular velocity*/
fi = 90*pi/180; /*phase difference*/
/*defining the flapping motion*/
vel[1] = 0.5*w*cos(w*time+Fi); /*Heaving motion*/
omega[2]=a*w*cos(w*time+Fi); /*pitching motion*/
}
By using the second UDF the airfoil pitches in the range of -30 to 0 and heaves in the range of -1 to 0.




if I change the UDF in this way:
vel[1] = 0.5*w*cos(w*time+Fi); /*Heaving motion*/
omega[2]=a*w*cos(w*time); /*pitching motion*/
Just the heaving amplitude would be wrong,in the range of -1 to 0


It's expected to pitches in the rage of -15 to 15 and heaves in the range of -0.5 to 0.5

How could I fit this problem and define the phase difference for the fluent without getting false results?
Again, simulating a flapping motion which phase difference is zero has been simulated well!
Thanks in advance
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Old   March 26, 2020, 13:24
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JOHN
Join Date: Nov 2019
Location: India
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hello sir,
I have a similar kind of UDF problem. I m curious if you have found the results and a working UDF. please help.
Thanks
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