[smagmon]

Hi all,
I am around a FSI simulation problem.
I have a closed tube with stationary water (no flow) initially. In one side of this tube, I set a BC as WALL with a mesh displacement . The specified displacement is given as a step function through CEL. All other boundaries are set to Stationary WALL. If I set water to be compressible (also using CEL), after running the model in CFX, I can observe pressure wave propagation.
As I have a converged solution for the fluid simulation, I started trying a FSI simulation, changing one of the stationary walls to ANSYS MULTI-FIELD option in mesh motion, and creating a /prep7 file in order to have a flexible wall in the other side (as a circular plate). I used ANSYS MFX for settings between Mechanical and CFX.
When I run the simulation many notices like bellow are given by CFX side, and then it crashes giving the following error.

+--------------------------------------------------------------------+
| ****** Notice ****** |
| While evaluating Static Enthalpy, |
| Static Pressure |
| went outside of its lower limit. Its minimum value was |
| -4.3869E+05. The bounds error was handled by clipping. |
| If this situation persists, consider increasing the table range. |
+--------------------------------------------------------------------+
----------------------------------------------------------------------
| COUPLING/STAGGER ITERATION = 3 |
----------------------------------------------------------------------
| SOLVING : Mesh Displacement |
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+
| X-Disp | 1.00 | 3.0E-02 | 1.0E+00 | 8.6E-03 OK|
| Y-Disp | 1.00 | 1.0E-03 | 2.2E-02 | 1.1E-02 OK|
| Z-Disp | 1.00 | 1.0E-03 | 2.2E-02 | 8.8 1.1E-02 OK|
+----------------------+------+---------+---------+------------------+
| X-Disp | 0.01 | 4.3E-04 | 3.7E-03 | 1.0E-01 OK|
| Y-Disp | 0.01 | 1.4E-05 | 1.7E-04 | 5.2E-02 OK|
| Z-Disp | 0.01 | 1.4E-05 | 1.6E-04 | 24.3 5.2E-02 OK|
+----------------------+------+---------+---------+------------------+
| X-Disp | 0.18 | 7.7E-05 | 9.9E-04 | 9.8E-02 OK|
| Y-Disp | 0.14 | 2.0E-06 | 4.6E-05 | 3.4E-02 OK|
| Z-Disp | 0.14 | 2.0E-06 | 4.6E-05 | 24.3 3.3E-02 OK|
+----------------------+------+---------+---------+------------------+
| X-Disp | 0.21 | 1.6E-05 | 2.7E-04 | 8.5E-02 OK|
| Y-Disp | 0.16 | 3.2E-07 | 7.7E-06 | 3.0E-02 OK|
| Z-Disp | 0.16 | 3.1E-07 | 7.8E-06 | 24.3 2.9E-02 OK|
+----------------------+------+---------+---------+------------------+
| X-Disp | 0.20 | 3.3E-06 | 5.1E-05 | 8.2E-02 OK|
| Y-Disp | 0.16 | 5.1E-08 | 1.3E-06 | 2.4E-02 OK|
| Z-Disp | 0.16 | 4.9E-08 | 1.2E-06 | 24.3 2.4E-02 OK|
+----------------------+------+---------+---------+------------------+

+--------------------------------------------------------------------+
| ERROR #002100011 has occurred in subroutine cVolSec. |
| Message: |
| A negative SECTOR volume has been detected. Execution will proceed |
| but this is a possible cause of robustness problems. |
| The location of the first negative volume is reported below. |
| Volume : -0.1307E-12 |
| Location : ( 0.16305E-01, -0.47543E-03, -0.27501E-02) |
| This warning may be made fatal by setting the expert parameter |
| 'negative volume option = 1'. |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #002100012 has occurred in subroutine cVolSec. |
| Message: |
| A negative ELEMENT volume has been detected. This is a fatal |
| error and execution will be terminated. The location of the first |
| negative volume is reported below. |
| Volume : -0.3001E-11 |
| Location : ( 0.16099E-01, -0.74617E-03, -0.25828E-02) |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| CFX encountered the error: |
| 0. A folded mesh has oc- |
| curred. This process will shut down as soon as possible. |
| |
| |
| |
+--------------------------------------------------------------------+

Is the "Notice" related to the error? I already tried to do what it advices, changing the range table, but it doesn't work.
When I change the fluid to air as ideal gas instead of water the the notice and error don't come.

Is my description clear?

Somebody knows what can be my problem?


Any tip or constructive commentary will be extremely appreciated, or even questions about my model, please let me know.

Thanks