# transportProperties

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

 December 4, 2012, 20:24 transportProperties #1 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,077 Blog Entries: 4 Rep Power: 19 Hi all, i want to simulate an liquid cooler for a CPU. For that I had a look into the solvers and thought that the solver Code: buoyantBoussinesqSimpleFoam for turbulent incompressible fluids are good. For that I have to change the transportProperties file from air into water (25°C) Code: transportModel Newtonian; // Laminar viscosity nu nu [0 2 -1 0 0 0 0] 0.89e-06; // Thermal expansion coefficient beta beta [0 0 0 -1 0 0 0] 0.0018; // Reference temperature TRef TRef [0 0 0 1 0 0 0] 298; // Laminar Prandtl number Pr Pr [0 0 0 0 0 0 0] 6.1; // Turbulent Prandtl number Prt Prt [0 0 0 0 0 0 0] 0.38; Are this settings correct? How can I estimate the turbulent prandtl number in that problem? In my case I calculated the turbulent prandtl with that equation: Code: Prt = 0.7 * a / nu_t With the turbulence calculator on that website I calculated k and omega from U, I and length scale. After that I calculated mu/mu_t and then nu_t = mu_t/rho. Is that correct? Thanks in advance Tobi

 December 5, 2012, 04:55 #2 Senior Member   Bernhard Join Date: Sep 2009 Location: Delft Posts: 790 Rep Power: 12 The turbulent Prandtl number is not really a property of the liquid. You obtain it from the Boussinesq (or gradient diffusion) hypothesis (not to be confused with the Boussinesq approximation) from the turbulent heat flux, and then it is assumed that scales wit or , but this is by no means a way to estimate the turbulent Prandtl number. It is a property of the turbulence more than a property of the liquid. I think in general, is somewhere in the range 0.7 to 0.9. But please read a bit more on this in books or papers to be absolutely sure.

 December 30, 2012, 04:30 multiRegionLiquidHeater #3 Senior Member     ahmed Join Date: Feb 2010 Posts: 161 Blog Entries: 1 Rep Power: 7 Dear Tobi, a good start could be from a neighbor case multiRegionLiquidHeater .it contains a file for water properties. regards,

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post suraj OpenFOAM Post-Processing 1 June 11, 2012 14:34 michielm OpenFOAM Running, Solving & CFD 4 April 29, 2012 06:48 jochemvandenbosch OpenFOAM Running, Solving & CFD 3 December 23, 2011 08:44 NickolasPl Main CFD Forum 0 June 2, 2011 14:06 klausb OpenFOAM 1 March 6, 2011 22:30

All times are GMT -4. The time now is 17:28.