# FSI of perpendicular flap for validation of oliver et al paper

**URL:** <https://precice.discourse.group/t/fsi-of-perpendicular-flap-for-validation-of-oliver-et-al-paper/2094>\
**Category:** Using preCICE\
**Tags:** openfoam, calculix, fsi\
**Created:** [August 30, 2024, 6:54pm UTC](https://precice.discourse.group/t/fsi-of-perpendicular-flap-for-validation-of-oliver-et-al-paper/2094 "2024-08-30T18:54:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![John\_Philip](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/john_philip/32/2410_2.png) [@John\_Philip](https://precice.discourse.group/u/John_Philip)\
**Post date:** [August 30, 2024, 6:54pm UTC](https://precice.discourse.group/t/fsi-of-perpendicular-flap-for-validation-of-oliver-et-al-paper/2094/1 "2024-08-30T18:54:18Z")

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I am trying to validate a research paper for perpendicular flap case. I did the meshing in ansys fluent for openfoam and gmsh for calculix. After running it parallely for 10s, the courant umber is increasing like anything at t=2.3s and simulation is crashing. I think there is something to do with the meshing but i am not able to figure out the error.

 ![Screenshot from 2024-08-30 23-52-15](https://global.discourse-cdn.com/free1/uploads/precice/original/2X/5/50e960f58eeca47dbc0ee37935b8e1b2ea08fcb5.png)  
 ![Screenshot from 2024-08-30 23-52-41](https://global.discourse-cdn.com/free1/uploads/precice/original/2X/1/185ba76b101f575c36db7df288e7f529f6534ae8.png)

[flap.inp](https://precice.discourse.group/uploads/short-url/cd01UoBnpaEItKF9Yx2GhJs19bR.inp) (407 Bytes)  
[precice-config.xml](https://precice.discourse.group/uploads/short-url/oIxVvA57kQtybuRPeVHGtLxczIA.xml) (2.4 KB)  
[Perpendicular-flap-validationcase\_copy1.zip](https://precice.discourse.group/uploads/short-url/hhhlFDIONfUxVv9GCbiWFmk49aP.zip) (2.9 MB)

I have tried the paper above.  
i have taken  
density of fluid as 10^3 kg/m^3  
also for case A density of solid will be 10^6 kg/m^3  
Uinf =1m/s  
poissons ratio =0.45 (given)  
Re =1000 (given)  
E\* =6 x 10^4 (given) , so E = 6 x 10^7  
Lo =1m  
to =0.05m  
Distance of perpendicular flap from inlet and outlet is 5m.  
I have attached the whole case above. In the file it has .msh file with which i generated the polymesh file (all ready generated).  
Can anyone help me with where is error is occuring ? If it is with the meshing, how should I do the meshing part. If it is with the setting part please point out the error.  
My time step is 0.001s

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**Author:** ![Makis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/makis/32/25_2.png) [@Makis](https://precice.discourse.group/u/Makis)\
**Post date:** [September 1, 2024, 9:11am UTC](https://precice.discourse.group/t/fsi-of-perpendicular-flap-for-validation-of-oliver-et-al-paper/2094/2 "2024-09-01T09:11:17Z")

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How does the mesh close to the interface look like just before the simulation crashes?  
Are any cells breaking?

We faced similar issues with the FSI2 case in the OpenFOAM adapter paper ([OpenFOAM-preCICE: Coupling OpenFOAM with External Solvers for Multi-Physics Simulations | OpenFOAM® Journal](https://journal.openfoam.com/index.php/ofj/article/view/88)), which we associated with the mesh motion solver we were using. The FSI3 case was working fine.