CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Natural convection from heatsink

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

LinkBack Thread Tools Display Modes
Old   November 18, 2013, 10:12
Default Natural convection from heatsink
New Member
Join Date: Nov 2013
Posts: 2
Rep Power: 0
freefall is on a distinguished road

I'm currently simulation natural convection in 3-D from a plate-finned heatsink with multiple heatgenerators.

I use pressure-based solver, with gravity.

  • Energy equation
  • k-epsilon turbulence, with scalable wall fc and full bouancy effects.
  • P1, with emissivity:0,85 on most solids.
i use Simplec with discretizations:
  • standard pressure
  • Second order on the others
as materials there is only air and aluminium

Questions regarding air properties:

  1. How do i best define density for air here? I have used mostly boussinesq approx. Here i wonder what sould i define operating temerature as? (in operating conditions) Should it be my ambient air temperature, or should it be the same temperature as the boussinesq density is defined (in materials) I have also tried incompressible ideal gas with a defined density (in operating conditions) With this it seems to get alot hotter, about 10 degrees...
  2. An is it possible/meaningful to use piecewise polynomial to define thermal conductivity, Cp and viscosity and still get convergence? Or should i define them as constants?
freefall is offline   Reply With Quote

Old   November 18, 2013, 10:14
New Member
Join Date: Nov 2013
Posts: 2
Rep Power: 0
freefall is on a distinguished road
forgot to mention that my deltaT is around 40 degrees at the most, So Ra=laminar.
freefall is offline   Reply With Quote


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
Thermophysical properties for natural convection Ciefdi OpenFOAM Running, Solving & CFD 0 November 7, 2013 12:44
Flow around cube and cube natural convection Mirage12 OpenFOAM Running, Solving & CFD 5 June 15, 2013 11:20
natural convection problem with radiation jorien CFX 0 October 14, 2011 09:26
Coupled vs Seg - Natural vs. Forced Convection Alex Siemens 5 December 12, 2007 05:58
natural convection at high Rayleigh mauricio FLUENT 2 February 23, 2005 20:43

All times are GMT -4. The time now is 06:40.