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

Non Boussinesq approximation

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 30, 2013, 08:31
Smile Non Boussinesq approximation
  #1
New Member
 
Hari
Join Date: Jan 2013
Posts: 4
Rep Power: 13
design_amrita is on a distinguished road
Hi,
I need to simulate natural convection in square cavity (bottom wall heated) without using Boussinesq approximation. I need to take the density changes into account with non-Boussinesq approximation. Can I solve this with an incompressible solver with treating density as constant? I need help about the formulation and way of solving.

With regards,
Hari
design_amrita is offline   Reply With Quote

Old   January 30, 2013, 09:15
Default
  #2
Senior Member
 
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,849
Rep Power: 73
FMDenaro has a spectacular aura aboutFMDenaro has a spectacular aura aboutFMDenaro has a spectacular aura about
Quote:
Originally Posted by design_amrita View Post
Hi,
I need to simulate natural convection in square cavity (bottom wall heated) without using Boussinesq approximation. I need to take the density changes into account with non-Boussinesq approximation. Can I solve this with an incompressible solver with treating density as constant? I need help about the formulation and way of solving.

With regards,
Hari
if you are outside the hypothesis of linearity (small variation of temperature) required by Bousinnesq model, you must use the full compressible model
FMDenaro is offline   Reply With Quote

Old   February 5, 2013, 09:04
Smile Non Boussinesq approximation
  #3
New Member
 
Hari
Join Date: Jan 2013
Posts: 4
Rep Power: 13
design_amrita is on a distinguished road
Thank you for replying. I need to develop a pressure based solver without boussinesq approximation. Is it possible to work on incompressible flows without treating density as constant.
design_amrita is offline   Reply With Quote

Old   February 5, 2013, 09:37
Default
  #4
agd
Senior Member
 
Join Date: Jul 2009
Posts: 357
Rep Power: 19
agd is on a distinguished road
If the density can vary, then the flow by definition is not incompressible. however, you can develop segregated solvers for variable density flows. One example of such a solver can be found in a JCP paper by Hou and Mahesh. If you put their names into google scholar, the second or third entry will point you to a pdf version of that paper.
agd is offline   Reply With Quote

Old   February 5, 2013, 10:42
Default Non Boussinesq approximation
  #5
New Member
 
Hari
Join Date: Jan 2013
Posts: 4
Rep Power: 13
design_amrita is on a distinguished road
Thankyou for replying.
I was referring to the following ASME J.heat transfer paper where they say the flow is incompressible with non boussinesq approximation in a differentially heated cavity. I have mentioned the details of the paper below.

A Numerical Simulation of Combined Radiation and Natural Convection in a Differential Heated Cubic Cavity
P. Kumar and V. Eswaran
J. Heat Transfer,2010,Volume 132,Issue 2,
design_amrita is offline   Reply With Quote

Old   February 5, 2013, 11:28
Default Non Boussinesq approximation
  #6
Senior Member
 
Jonas T. Holdeman, Jr.
Join Date: Mar 2009
Location: Knoxville, Tennessee
Posts: 128
Rep Power: 18
Jonas Holdeman is on a distinguished road
Quote:
Originally Posted by agd View Post
If the density can vary, then the flow by definition is not incompressible.
But doesn't "incompressible" just mean that the density is not a function of pressure? Isn't constant density just an additional simplification? I would think that an (idealized) incompressible fluid could still have the density a function of temperature or concentration. Isn't bouyancy just the result of density differences?
Jonas Holdeman is offline   Reply With Quote

Old   February 6, 2013, 10:01
Default
  #7
Senior Member
 
ztdep's Avatar
 
p ding
Join Date: Mar 2009
Posts: 427
Rep Power: 19
ztdep is on a distinguished road
Send a message via Yahoo to ztdep Send a message via Skype™ to ztdep
Quote:
Originally Posted by Jonas Holdeman View Post
But doesn't "incompressible" just mean that the density is not a function of pressure? Isn't constant density just an additional simplification? I would think that an (idealized) incompressible fluid could still have the density a function of temperature or concentration. Isn't bouyancy just the result of density differences?
we should define the incompressible by "partial P/partial rho", in natural convecion problem, the density varies, but it is still a incompressible flow.
ztdep is offline   Reply With Quote

Reply


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
InterFoam with boussinesq approximation sinusmontis OpenFOAM Running, Solving & CFD 2 October 25, 2020 13:21
Boussinesq approximation, help please! engahmed FLUENT 0 May 20, 2010 12:25
Question on boussinesq approximation panos_metal FLUENT 1 January 11, 2010 12:18
boussinesq approximation jamal FLUENT 2 March 25, 2008 09:57
Boussinesq approximation again Gabriel Main CFD Forum 3 May 11, 2000 10:24


All times are GMT -4. The time now is 14:17.