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

High velocity in Laminar flow

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 3, 2016, 05:37
Default High velocity in Laminar flow
  #1
New Member
 
cfdRocker
Join Date: Jun 2011
Posts: 5
Rep Power: 15
Manojmech is on a distinguished road
Hi all Fluent users,

I tried searching solution to my problem in this forum but I dint get or I have missed out somewhere. PLEASE HELP!!!!!

Geometry:
My geometry is really small of the order of millimeters. Geometry is complex and unfortunately I cannot post any pictures due to company confidentiality. But I will try to explain as much as I can.

There is single inlet and 15 outlets. We have to optimize the design so that all 15 outlets has almost equal flow distribution. Between inlet and outlet, fluid goes around complex geometry. We expect the flow to be laminar hence I used laminar flow model. You can imagine a flow is happening in a very small space between two plates.

Meshing : ICEMCFD tetmesh. I cannot do hexahedral mesh because the geometry is very complex. Quality is around 0.3.

Boundary Conditions :

Fluid : Hydrogen Gas
Inlet : Pressure inlet : Gauge Total Pressure : 80000 pascal
Outlet : All 15 outlets : Gauge Pressure : 50000 pascal
Operating Pressure : 101325 pascal
Model : Laminar
Model is symmetric hence modelling only half with symmetric BC.

INITIALIZATION: Gauge pressure : 101325 pascal
X,Y, Z Velocity = 0m/s
Reference frame : Relative cell zone


Results :

Pressure distribution seems to be fine.
Mass flow rate at the inlets and outlets match properly . ( Whatever goes in , goes out ). Also mass flow rate is somewhat close to what we expected.

PROBLEM : Maximum Velocity magnitude across the cross section of the geometry is showing around 600m/s and thats nearly mach 2.0. Though flow distribution pattern is ok but values of max velocity magnitude is not matching.

PROBLEM with VISUALIZATION :
Though pressure distribution is smooth contour, Velocity distribution is not smooth and little pixelleted. I tried changing nodes values on and off, display profiles -> projection direction in all direction but to no avail.

TRIED : I tried importing the model in CFX post but I am having same results and pixelled velocty magnitude contours.

I would like to have some thoughts on this. Please let me know if any other information you need to solve this problem. Also please post a link of any discussion if happened before.

Regards,
Manoj
Manojmech is offline   Reply With Quote

Reply

Tags
#fluent, #highvelocity, #laminar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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
Problem with time average tangential velocity in swirl flow. lakhi FLUENT 5 July 18, 2012 17:28
high velocity flow - problem with convergence Kevin88 Main CFD Forum 4 May 24, 2012 07:40
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 16:45
Can 'shock waves' occur in viscous fluid flows? diaw Main CFD Forum 104 February 16, 2006 06:44
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 10:11


All times are GMT -4. The time now is 00:42.