|
[Sponsors] |
reversed flow on faces limited in 643 cells in region out |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
September 19, 2009, 06:10 |
reversed flow on faces limited in 643 cells in region out
|
#1 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
Hello everybody,
i am a newby and i dont know if introducing myself somewhere is required. Anyway i am 27years old marine engineer from italy approaching for the first time on cfd planet. I am asking for your help because any boat model i am trying to validate with cfd,return a message reporting what stated in the title of this thread "reversed flow on faces limited in 643 cells in region out"... I tryed to change volume control dimensions up to 2,5 time boat length,width and depth...but the message won't disappear....although performing grid parameters of my multiphase. So now i am trying with a second order solver...and the number of faces affected seem to get smaller iteration by iteration. Can anyone explain me what's the meaning of the above mentioned message and what's the smartest solution to fix similiar problems without affecting solution and its transient? i used velocity inlet and pressure outlet Many thanks in advance Last edited by emanuele; September 19, 2009 at 06:29. |
|
September 21, 2009, 11:22 |
|
#2 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
Check your conditions on the outlet boundary.
Sometimes it's normal because the flow reserves before it gets a straight flow. When I use a Pressure Outlet as a Inlet I get this on every iteration To check the direction I use vectors on the boundarys. |
|
September 21, 2009, 11:29 |
|
#3 | |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
Quote:
I would like to try a polyedral mesh in order to check if multifaces volumes can manage turbulent flow in a most accurate way...actually i m going with trimmer and its refinement on free surface.. |
||
September 21, 2009, 12:26 |
|
#4 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
Is your problem 2D or 3D?
When this is a 2D problem then your region is wrong. Show more pictures! |
|
September 21, 2009, 13:58 |
|
#5 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
my problem is a 3d problem and it don't wanto to converge!!I checked several times what should be wrong but i discovered nothing....
i performed mesh diagnostics and everything seems to be ok,i enlarged my continuum but nothing....solution keep going in a wrong way.I'll show more pic as soon as i can! i performed some trials without degrees of freedom in order to be sure it is not a prblem related to initial condition an moments of inertia...but it's the same.. |
|
September 21, 2009, 15:20 |
|
#6 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
What settings to you use? Wall treatment? y+?
Bring more facts plz |
|
September 22, 2009, 10:19 |
|
#7 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
ok,at the link below you can find my summary report ...
thank you for your big interest!! http://www.megafileupload.com/en/fil...umem-html.html |
|
September 22, 2009, 10:50 |
|
#8 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
Look at your courant number, maybe you have so choice a smaller time step.
|
|
September 22, 2009, 11:31 |
|
#9 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
||
September 22, 2009, 11:39 |
|
#10 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
Tell me when it works, picture looks very nice. Could be a really nice animation
|
|
September 25, 2009, 05:27 |
|
#11 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
ok...error found...i was using velocity modulus..At inlet flow direction is "inlet to outlet"...and you do not need to specify it using "-" or "+"...just use modulus of velocity
In continum you should specify everytime the direction of the flow....i was using positive velocity at inlet and positive velocity in continuum bu the direction of my cordinate system was with x axis directed in the same direction of boat advancing motion,so,to define velocity in continum i must use a negative value because water come forth my boat...differently i was experiencing vertices waves...the hell.. |
|
September 25, 2009, 06:17 |
|
#12 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
When I understand you right you didn't had seen/known that the velocity in the initial conditions is according the laboratory coordiante system?
Ok when I look at your picture know I see it. X-axle shows to the left so you must work with negativ flow when the flow direction is from left to right |
|
September 25, 2009, 06:22 |
|
#13 | |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
Quote:
|
||
September 25, 2009, 06:43 |
|
#14 |
Senior Member
Join Date: Mar 2009
Posts: 260
Rep Power: 18 |
Under Physics Conditions of the Boundary you can set the flow direction
You can also give a vector for the flow or "normal to boundary" or a angle. |
|
September 25, 2009, 06:47 |
|
#15 |
New Member
Join Date: Sep 2009
Posts: 19
Rep Power: 16 |
ok...the solution is:
be sure x axys si oriented as flow motion direction ...it is easyer... |
|
April 21, 2020, 13:44 |
|
#16 |
Senior Member
MA
Join Date: Mar 2020
Posts: 163
Rep Power: 6 |
so how did you introduce modulus of velocity? In my case, I have the blade which rotates in x-y plane and inlet is in z direction but in the coordinate system ''z'' points opposite to the inflow direction so I used -ve velocity value and it shows me the same message of reversed flow at outlet.
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Problem in IMPORT of ICEM input file in FLUENT | csvirume | FLUENT | 2 | September 9, 2009 01:08 |
Error to re-open fluent case file | J.Gimbun | FLUENT | 0 | April 27, 2006 08:42 |
[Commercial meshers] Trimmed cell and embedded refinement mesh conversion issues | michele | OpenFOAM Meshing & Mesh Conversion | 2 | July 15, 2005 04:15 |
fluid flow fundas | ram | Main CFD Forum | 5 | June 17, 2000 21:31 |
Flow visualization vs. Calculated flow patterns | Francisco Saldarriaga | Main CFD Forum | 1 | August 2, 1999 23:18 |