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Radially varying heatflux UDF - Ansys Fluent

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Old   May 8, 2018, 05:27
Default Radially varying heatflux UDF - Ansys Fluent
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mokong
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Dear Users,

I am trying to model friction stir welding process in ansys fluent. There are three domains as part of my simulation.

1. Domain 1 - Moving Workpiece - Fluid (this domain has a recess in which domain 2 is rotating)
2. Domain 2 - Rotating Workpiece - Fluid (this domain is present in the recess in domain 1 )
3. Domain 3 - Tool - Solid

See attached link to see images of the model.


I am trying to apply a radially varying heat flux to the tool bottom surface (also known as tool shoulder). I am using a UDF for this. The tool is positioned at (0,0,0). I have a function for calculating the total heat (in W) to be applied depending on the position. Heat flux (in W/m2) is then calculated from the total heat and applied to the tool shoulder. The issue with the UDF is that it does not loop over all the faces of the tool shoulder (which is a boundary face). The heat flux is only applied to the cell face at the edge of the shoulder. (see attached image for my results).

# include "udf.h"
DEFINE_PROFILE(heatfluxshoulder,thread,position)
{ face_t f;
cell_t c;
float x[ND_ND]; //define position vector
float xx,z,r,omega,w,sigma, uf,qs1,ql1,hflux,taustick, tauslide, rshoulder, rpin, pressure, yield, qtotal; //Define variables
begin_f_loop(f,thread) //begin face loop
{
pressure=17700;
yield=35000000;
omega=800;
rshoulder=0.014;
rpin=0.003;
w=2*3.14*omega/60;
F_CENTROID(x,f,thread); //calculate the face center position
xx=x[0]; //store the x coordinate in variable
z=x[2]; // store the z coordinate in variable
r=sqrt((xx*xx+z*z)); // calculate the radial position from (0,0,0)
sigma=0.31*exp(w*r/1.87)-0.026; //calculate coefficient based on
radius
uf=0.5*exp(-sigma*w*r); //calculate coefficient based on radius
taustick=yield/1.73;
tauslide=uf*pressure;
qs1=0.67*3.14*w*taustick*(rshoulder*rshoulder*rsho ulder-
rpin*rpin*rpin); //calculate heat based on radius
ql1=0.67*3.14*w*tauslide*(rshoulder*rshoulder*rsho ulder-
rpin*rpin*rpin); //calculate heat based on radius
qtotal=sigma*(qs1)+(1-sigma)*(ql1); // calculate total heat
hflux=(qtotal/4847)*1.7e+010; //calculate heat flux to be applied
(based on qtotal)
F_PROFILE(f,thread,position) = hflux; //apply heat flux to the face
}
end_f_loop(f,thread)
}

Guys, please help me to figure out why the heat flux is not being applied to all the faces of the tool shoulder.

https://drive.google.com/drive/folde...Fm?usp=sharing
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Old   October 25, 2020, 02:38
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Mahesh
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Hi farhanjaved,
I am also trying to develop a CFD model for FSW. Could you please explain how to arrive at these expressions of contact state variable "del" and friction coefficient "mu"? (Or any supporting theory for these two expressions)

sigma=0.31*exp(w*r/1.87)-0.026; //calculate coefficient based on
radius
uf=0.5*exp(-sigma*w*r); //calculate coefficient based on radius


Please help !!
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