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

boundary condition

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 16, 2007, 05:59
Default boundary condition
  #1
sumita
Guest
 
Posts: n/a
what will be the exact boundary condition for 2d and 3d airfoil.I had plotted in side a rectangular domain.there are 2 and 3 air foil togethar
  Reply With Quote

Old   December 16, 2007, 08:09
Default Re: boundary condition
  #2
Ramesh.K
Guest
 
Posts: n/a
Hi, The following boundary conditions may be adopted for any kind of air foils

a. at the surface of the airfoil it is no penetration condition b.in the far field region we have free stream velocity unchanged c. at the inlet and outlet u can have either velocity or pressure boundary conditions.

for further details u can see any basic aerodynamics book it is specified in the first or second chapters only

bye

  Reply With Quote

Old   December 19, 2007, 00:10
Default Re: boundary condition
  #3
Vijay
Guest
 
Posts: n/a
Hi sumitha,

Pressure far field is the only boundary condition u have to spcify and angle of attack for X, Y component.......

Regards, Vijay
  Reply With Quote

Old   December 22, 2007, 14:09
Default Re: boundary condition
  #4
sumita
Guest
 
Posts: n/a
But its not taking farfield condition
  Reply With Quote

Old   December 24, 2007, 01:51
Default Re: boundary condition
  #5
Ramesh. K
Guest
 
Posts: n/a
Hi,

For far field condition the domain should be large enough these are the things given the manual for farfield just go through it

Pressure far-field conditions are used in FLUENT to model a free-stream condition at infinity, with free-stream Mach number and static conditions being specified. The pressure far-field boundary condition is often called a characteristic boundary condition, since it uses characteristic information (Riemann invariants) to determine the flow variables at the boundaries.

! This boundary condition is only applicable when the density is calculated using the ideal-gas law (see Section 7.2). Using it for other flows is not permitted. To effectively approximate true infinite-extent conditions, you must place the far-field boundary far enough from the object of interest. For example, in lifting airfoil calculations, it is not uncommon for the far-field boundary to be a circle with a radius of 20 chord lengths.

if ur boundary is not far u can use this u should use pressure boundary condition at the outlet specifying the outlet pressure which u can predict it by Bernoulli principle.

hope this works out

bye

  Reply With Quote

Old   December 24, 2007, 01:53
Default Re: boundary condition
  #6
Ramesh. K
Guest
 
Posts: n/a
or u can also use outflow boundary conditions

# Pressure far-field boundary conditions are used to model a free-stream compressible flow at infinity, with free-stream Mach number and static conditions specified. This boundary type is available only for compressible flows.

# Outflow boundary conditions are used to model flow exits where the details of the flow velocity and pressure are not known prior to solution of the flow problem. They are appropriate where the exit flow is close to a fully developed condition, as the outflow boundary condition assumes a zero normal gradient for all flow variables except pressure. They are not appropriate for compressible flow calculation
  Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Boundary Conditions Thomas P. Abraham Main CFD Forum 20 July 7, 2013 05:05
Setting outlet Pressure boundary condition using CAFFA code Mukund Pondkule Main CFD Forum 0 March 16, 2011 04:23
Domain Imbalance HMR CFX 3 March 6, 2011 21:10
How exactly the "pressure outlet" bdry condition compute properties on the boundary? yating9901 FLUENT 3 June 28, 2010 12:26
How to set boundary condition in Fluent for the fo Peiyong FLUENT 1 November 10, 2006 12:44


All times are GMT -4. The time now is 04:39.