[n.soumya]

Hey guys

I need an help in 2 way FSI simulation.

Actually i am trying to silmulate flow past a blunt body using 2 way FSI with CFX module of ANSYS. But i am not able to simulate it correctly.

Every time i run cfx after some iteration it is showing fatal overflow in linear solver. The command window shows something like as shown below.


//**
----------------------------------------------------------------------
COEFFICIENT LOOP ITERATION = 21 CPU SECONDS = 4.802E+02
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+
| U-Mom | 0.00 | 3.5E-19 | 2.2E-17 | 4.6E+14 * |
| V-Mom | 0.00 | 8.3E-20 | 5.7E-18 | 1.1E+14 * |
| W-Mom | 0.00 | 8.7E-20 | 5.4E-18 | 1.1E+14 * |
| P-Mass | 0.00 | 1.4E-34 | 5.7E-33 | 8.8 2.2E+14 * |
+----------------------+------+---------+---------+------------------+
+--------------------------------------------------------------------+
| ****** Notice ****** |
| A wall has been placed at portion(s) of an OUTLET |
| boundary condition (at 18.6% of the faces, 16.4% of the area) |
| to prevent fluid from flowing into the domain. |
| The boundary condition name is: outlet. |
| The fluid name is: Fluid 1. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead. |
+--------------------------------------------------------------------+
| H-Energy |62.19 | 1.4E-02 | 4.1E-01 | 5.8 4.0E-04 OK|
+----------------------+------+---------+---------+------------------+

+--------------------------------------------------------------------+
| ERROR #004100018 has occurred in subroutine FINMES. |
| Message: |
| Fatal overflow in linear solver. |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+

End of solution stage.

+--------------------------------------------------------------------+
| The following transient and backup files written by the ANSYS CFX |
| solver have been saved in the directory |
| K:/Soumya/SAHOO_SIR_MODEL_2_WAY_FSI_0AOA_pending_tasks/dp0_CFX_So- |
| lution-1/CFX_001: |
| |
| 1_full.trn, 0_full.trn |
+--------------------------------------------------------------------+


+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| ANSYS Solver terminated with return code 256 |
+--------------------------------------------------------------------+


+--------------------------------------------------------------------+
| The results from this run of the ANSYS solver have been written to |
| K:\Soumya\SAHOO_SIR_MODEL_2_WAY_FSI_0AOA_pending_t asks\dp0_CFX_So- |
| lution-1\CFX_001.ansys |
+--------------------------------------------------------------------+


+--------------------------------------------------------------------+
| The following user files have been saved in the directory |
| K:/Soumya/SAHOO_SIR_MODEL_2_WAY_FSI_0AOA_pending_tasks/dp0_CFX_So- |
| lution-1/CFX_001: |
| |
| mon |
+--------------------------------------------------------------------+


This run of the ANSYS CFX Solver has finished.

**//


I have tried by shifting the outlet by a large distance from the end of the blunt body. But it does not work.

I can't also mention outlet as a opening because my outlet condition is supersonic.

Please recomend me what to do????

Thanks in advance.
Soumya

[IUTDavood]

Hi
By using the
1. SST turbulence method
2. Local time scale
3. high Mesh quality
this problem will be solved probably.

[ghorrocks]

This question refers to 2 FAQs:
http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

and

http://www.cfd-online.com/Wiki/Ansys...f_an_OUTLET.22