[Neo_Zeo]

Hello everyone!

I have the following problem:

I am modelling a transient problem about a VAWT (Vertical Axis Wind Turbine).

I have a beam which turns around the vertical axis. Over this beam I have 3 wings which also turns around. But I don`t want they to turn at a fixed RPM. They must be in a fixed angle in each quadrant.

I would like you to orient me about how to build my UDF.

-How can I do for Fluent to recognize the "beam rotation angle" variable?

-I have seen that I can use CG Motion to define velocities but I want to define positions. Is it possible? Or do I need to use velocities to do it?

-Is it possible to work with profiles? By the moment the profile I used works badly.

Thank you very much for your help


(Explanatory image attached)

[`e`]

You can define nodal positions as a function of time using the DEFINE_GRID_MOTION macro within the Moving/Deforming Mesh model.

I don't think profiles would work because they don't alter the flow field (only the boundaries). It'd be similar to changing the wind direction rather than moving the turbine blades.

[Neo_Zeo]

Originally Posted by `e`

You can define nodal positions as a function of time using the DEFINE_GRID_MOTION macro within the Moving/Deforming Mesh model.

I don't think profiles would work because they don't alter the flow field (only the boundaries). It'd be similar to changing the wind direction rather than moving the turbine blades.

Thank you!
I have created and load this UDF, but it doesn`t appear in Cell Zone ->Mesh Motion ->Zone Motion function. However it appears in dynamic mesh. Why?
What is the diference between grid and cg motion?

This is my udf file :

#include "udf.h"
DEFINE_CG_MOTION(lama1,dt,vel,omega,time,dtime)
{

/* reset velocities */
NV_S(vel, =, 0.0);
NV_S(omega, =, 0.0);

if (!Data_Valid_P())
return;

if (time < 2.3)
vel[1] = 0.04;
else if (time < 3.1)
vel[1] = 0;
else if (time < 3.3)
vel[1] = -7.2;
else if (time < 3.6)
vel[1] = -4.8;
else if (time < 5.6)
vel[1] = 0.7;
else if (time < 5.7)
vel[1] = -0.7;
else if (time < 6.0)
vel[1] = -1.0;
else if (time < 6.9)
vel[1] = 0.7;
else if (time < 7.9)
vel[1] = 0.8;
else if (time < 8.0)
vel[1] = 2.10;
else if (time < 8.2)
vel[1] = 1.70;
else if (time < 9.2)
vel[1] = 0;
else
vel[1] = 0;
}