[gfcfd]

Hi,

I'm trying to run a case using a velocity profile as an inflow boundary which does not change over time, and I'm not sure how to define it. I tried using the same velocity field at two different times, t=0 and t=1000, but when I look at the solution the velocity is changing on the boundary. Does anyone have an example of what the input should look like?

the input velocity profile looks like this:

SPATIAL
1.0 scale_xyz
0.0 trans_x
0.0 trans_y
0.0 trans_z
x rot_axis
0.0 rot_angle

0.0 second
x y z u v w
0.01664349 -0.005407783 0.001999584 0.5882305065 -1.8103922722 2.47E+00 [...]

1000.0 second
x y z u v w
0.01664349 -0.005407783 0.001999584 0.5882305065 -1.8103922722 2.47E+00
[...]

Thanks

[xieshengbai]

Hi,

The profile looks OK to me. The variation of velocity profile may be because:

1) CONVERGE does not output velocity on the boundaries, so the velocity profile you observed is actually the velocity profile at the first layer cells. Slight variation is allowed there.

2) If AMR happens near the inflow, the velocity profile will also change, because CONVERGE uses the "nearest point" method to map input velocity profile to boundary faces.

Note that you can keep only 0.0 second section, and 1000.0 second section is unnecessary in this case.

If possible, you can post some figures or movie here, so that we can see how big the variation is. Or you can send them as well as your case setup to us at support@convergecfd.com.

Thank you.

Originally Posted by gfcfd

Hi,

I'm trying to run a case using a velocity profile as an inflow boundary which does not change over time, and I'm not sure how to define it. I tried using the same velocity field at two different times, t=0 and t=1000, but when I look at the solution the velocity is changing on the boundary. Does anyone have an example of what the input should look like?

the input velocity profile looks like this:

SPATIAL
1.0 scale_xyz
0.0 trans_x
0.0 trans_y
0.0 trans_z
x rot_axis
0.0 rot_angle

0.0 second
x y z u v w
0.01664349 -0.005407783 0.001999584 0.5882305065 -1.8103922722 2.47E+00 [...]

1000.0 second
x y z u v w
0.01664349 -0.005407783 0.001999584 0.5882305065 -1.8103922722 2.47E+00
[...]

Thanks

[gfcfd]

The problem was the time step was too small. When I increased the time step the inlet changes in the beginning but then stabilizes.

[xieshengbai]

Good to know that the problem was solved.

Originally Posted by gfcfd

The problem was the time step was too small. When I increased the time step the inlet changes in the beginning but then stabilizes.