[K.Arimoto]

I am a newbie in analysis.
We are currently experimenting with a rotary engine and would like to do some analysis. In particular, how can the movement from the intake to the compression process be given on the CFD?
If you have ever experienced a rotary engine, please help! !
I would be grateful if you could tell me more about how to analyze the rotary engine in ANSYS R2

[vinerm]

What kind of rotary engine is it? Depending upon the type, motion could be done using mesh motion or might require dynamic mesh with remeshing.

[K.Arimoto]

Thank you for your reply.
What I am currently doing is a "Wankel type" rotary engine.
By the way, ANSYS is not a paid one, it is used for academic purposes.

[vinerm]

For Wankel engine, you may have to use 2.5 D remeshing. It requires triangular prisms throughout the deforming domain. As the rotor rotates, remeshing is done in the plane of rotation and then extended automatically along the axis of rotation. Look at the following

https://www.mr-cfd.com/h.e.khoshmard...g%20Method.pdf

It doesn't matter whether it is paid or not; the only difference is in the cell count otherwise all the features are same.

[K.Arimoto]

Thank you.
There are other points that I do not understand.
I found out that I needed UDF to reproduce the movement of the rotor.

From the UDF quoted from within this forum,
#include "udf.h"
#define NCOORDS 360
#define r 50
#define its 180
#define pi 3.1415926

DEFINE_CG_MOTION(eccentric, dt, vel, omega, time, dtime)
{
NV_S (vel, =, 0.0);
NV_S (omega, =, 0.0);
omega[2] = -1.0;
}


DEFINE_GEOM(housing, domain, dt, position)
{
int i,j;
real rad, x, y;
int start=0;

for(i=0;i<=NCOORDS;i++)
{
for(j=start;j<=start+its;j++)
{
j=j%360;
rad = ((j * pi )/ 180);
position[0] = r * cos(rad);
position[1] = r * sin(rad);
}
start=start+1;
}
}

Is this possible for UDF used in Wankel engine?

Also, please tell me in detail about the settings that give the movement of the Wankel engine.

[vinerm]

I have my doubts about it since the rotor does not just rotate but its center rotates as well, which is not given in the UDF. So, you should check the source of this UDF; where you got it from.

Best way to check it is to apply it and run only mesh. Do not solve any equations. Check the mesh motion.

[K.Arimoto]

Thank you for your reply.
Another thing I would like you to confirm is whether it is a UDF.

#include "udf.h"
#define r -0.015 /*Eccentricity*/
#define k 57.2727 /*rad to degree*/
#define w 314.16 /*angular velocity in rad/sec*/

DEFINE_CG_MOTION (rotor, dt, vel, omega,time, dtime)
{
real beta;

NV_S(vel, =, 0.0);
NV_S(omega, =, 0.0);
omega[2] = 314.26;/*angular velocity in rad/sec*/
beta = 942.48; /*angular velocity of rotor in rad/sec*/

vel[0] = -beta * r * sin(beta * time);
vel[1] = beta * r * cos(beta * time);
vel[2] = 0;

}
I also found this in the forum.
Can you reproduce the movement of the rotor with this?

[vinerm]

Yes, it is a UDF. To check the motion, just compile it and hook it at the right place. This will work only with Dynamic Mesh. Then, display the zone motion (don't display mesh motion). If the motion is correct, then you can proceed further.