CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Convergence and backflow problem in cavitation simulation

Register Blogs Community New Posts Updated Threads Search

 
 
LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
Old   August 9, 2016, 07:38
Default Convergence and backflow problem in cavitation simulation
  #1
New Member
 
Burak Altıntaş
Join Date: Apr 2016
Posts: 6
Rep Power: 10
burakaltintas is on a distinguished road
Hi,

I am running steady, periodic cavitation case for the out-design parameters of a Francis runner. it has 4 million boundary layer mesh (unstructured), all y+ values on the blade are lower than 2. Max aspect ratios in layers are lower than 10000( I read that this is acceptable for boundary layer meshes).

I have two problem. Firstly, my single phase simulations,which are used as initial guess, were converged to 1e-5. However, the cavitation simulations have not converged to 1e-5. Secondly, some runs give backflow in both inlet and outlet, is it normal? if it is not normal, how can i cope with it.

Any help will make me happy!



A wall has been placed at portion(s) of an INLET |
| boundary condition (at 15.8% of the faces, 0.1% of the area) |
| to prevent fluid from flowing out of the domain. |
| The boundary condition name is: R1 Inlet. |
| The fluid name is: Water. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ****** Notice ****** |
| A wall has been placed at portion(s) of an INLET |
| boundary condition (at 15.8% of the faces, 0.1% of the area) |
| to prevent fluid from flowing out of the domain. |
| The boundary condition name is: R1 Inlet. |
| The fluid name is: Vapour. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ****** Notice ****** |
| A wall has been placed at portion(s) of an OUTLET |
| boundary condition (at 8.1% of the faces, 0.3% of the area) |
| to prevent fluid from flowing into the domain. |
| The boundary condition name is: R1 Outlet. |
| The fluid name is: Water. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead. |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| ****** Notice ****** |
| A wall has been placed at portion(s) of an OUTLET |
| boundary condition (at 8.1% of the faces, 0.3% of the area) |
| to prevent fluid from flowing into the domain. |
| The boundary condition name is: R1 Outlet. |
| The fluid name is: Vapour. |
| If this situation persists, consider switching |
| to an Opening type boundary condition instead.
burakaltintas is offline   Reply With Quote

 


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
2D Hypersonic Inlet in FLUENT - Convergence Issues Fraisdegout FLUENT 6 December 15, 2016 02:07
Convergence and backflow problem in cavitation simulation burakaltintas CONVERGE 2 August 9, 2016 07:42
Buoyancy issue in free and forced convection problem sosat1012 CFX 4 June 4, 2015 11:12
Backflow at outlet in a Eulerian gas-solid simulation audrey CFX 10 October 25, 2012 06:15
Modeling Backflow for a 3D Airfoil (Wing of Finite Span) Josh CFX 9 August 18, 2009 11:31


All times are GMT -4. The time now is 15:39.