|
[Sponsors] |
Symmetric vs. complete model solution stability |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
July 16, 2017, 13:03 |
Symmetric vs. complete model solution stability
|
#1 |
New Member
Emilio
Join Date: Jul 2017
Posts: 3
Rep Power: 9 |
Hi everybody,
I am running the transient case of an external compressible (M=0.6) flow around a 3D flat ellipsoid. The body, which has a circular planform, a relative thickness of 0.2 and no sharp trailing edge, has to perform two sine-wave movements: a lateral asymmetric movement and a foreaft symmetric movement. The solution is performed using the inviscid equations and the density-based solver in both full-model and half-model meshes. The full-model (no symmetry) case is initialized with the steady solution. However, when the initial transient effects disappear, the lift monitor does not show a periodic behaviour, and some erratic fluctuations appear in both lateral and foreaft movements. On the other hand, when a half-model is used with a symmetry boundary condition, the forces in the model show a stable periodic behaviour (foreaft movement). I need to use the complete model for performing the lateral movement solution. Can this behaviour be due to the lack of symmetry in the mesh (tetra-mesh with ANSYS Meshing)? Or could there be any other source of instability, like the absence of a sharp trailing edge? Any possible solution? I appreciate any help! Regards, Emilio |
|
July 18, 2017, 11:57 |
|
#2 |
Senior Member
Blanco
Join Date: Mar 2009
Location: Torino, Italy
Posts: 193
Rep Power: 17 |
I think that a non-symmetric mesh can be the root cause of the described behavior, even if you have to check however for solver convergence at each time-step.
Btw, what about trying to obtain a full-scale mesh starting from the half-model mesh? If I remember well you can mirror the mesh before exporting it in ANSYS, so you can still use your half-model mesh, mirror it, merge vertices and boundaries where needed and then obtain a full-model mesh for your simulation (this way assuring a mesh symmetry along a desired axis). |
|
Tags |
inviscid, stability, symmetry |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
solution algorithm of the k-omega model | M-ISMAIEL | Main CFD Forum | 0 | January 5, 2016 13:08 |
Asymmetric solution for bluff bodies symmetric tandem | bud_el_lodituma | Main CFD Forum | 7 | March 18, 2014 16:07 |
Water subcooled boiling | Attesz | CFX | 7 | January 5, 2013 04:32 |
Error in Axi symmetric model. | binubtharayil | FLUENT | 2 | August 5, 2009 17:01 |
Wall functions | Abhijit Tilak | Main CFD Forum | 6 | February 5, 1999 02:16 |