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

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 September 20, 2018, 04:49 Simulating a flapping airfoil by Fluent which the phase difference equals to 90 #1 Member   Hanye Azimi Join Date: Oct 2016 Posts: 42 Rep Power: 9 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

 March 26, 2020, 13:24 #2 New Member   JOHN Join Date: Nov 2019 Location: India Posts: 1 Rep Power: 0 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

 Tags flapping, fluent, phase difference, udf

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