precice-config-explicit.xml (1.8 KB)

The configuration is attached.

I’m testing and learning the coupling procedure for a further FSI problem. So I use python for both Fluid and Solid solvers.

The solid solver calculate the deflection of a a flap based on the force from the fluid solver. The grid points are artificially created in a one-dimension fashion. Since preCICE needs 2D or 3D meshes, I set all the x-coordinates zero for a vertical flap and only y coordinates are set accordingly).

For fluid, the first half use a small dx, and the second half use a larger increment.

`

grid = np.zeros([ns, dimensions])

grid[:, 1] = np.linspace(0, length, ns) # y component

dx = grid[1,1] - grid[0,1]

for i in range(1, ns):

```
if i < ns/2:
grid[i,1]=grid[i-1,1] + dx/2
else:
grid[i,1]=grid[i-1,1] + 3/2*dx
```

`

The solid grid is uniformly created:

`

grid = np.zeros([ns, dimensions])

grid[:, 1] = np.linspace(0, length, ns) # y component

grid[:, 0] = 0 # x component, leave blank

`

It seems the solution blows up after some iteration with non-matching mesh. For non-conforming uniform meshes, it runs well.

The error message given by the solid participant is as follows:

Solid: Advanceing in time

—[precice] Time window completed

—[precice] iteration: 1, time-window: 277, time: 2.76 of 100, time-window-size: 0.01, max-timestep-length: 0.01, ongoing: yes, time-window-complete: yes,

OK3

Iter = 276, Err = 9.76966e-01

Solid: Advanceing in time

—[precice] Time window completed

—[precice] iteration: 1, time-window: 278, time: 2.77 of 100, time-window-size: 0.01, max-timestep-length: 0.01, ongoing: yes, time-window-complete: yes,

OK3

Iter = 277, Err = 1.00000e+00

Solid: Advanceing in time

—[precice] Time window completed

—[precice] iteration: 1, time-window: 279, time: 2.78 of 100, time-window-size: 0.01, max-timestep-length: 0.01, ongoing: yes, time-window-complete: yes,

OK3

Iter = 278, Err = nan

Solid: Advanceing in time

—[precice] Time window completed

—[precice] iteration: 1, time-window: 280, time: 2.79 of 100, time-window-size: 0.01, max-timestep-length: 0.01, ongoing: yes, time-window-complete: yes,

Iter = 279, Err = nan

`Solid: Advanceing in time ---[precice] Time window completed ---[precice] iteration: 1, time-window: 281, time: 2.8 of 100, time-window-size: 0.01, max-timestep-length: 0.01, ongoing: yes, time-window-complete: yes, OK3 Iter = 280, Err = nan`