# K - Epsilon values

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

 March 4, 2001, 18:59 K - Epsilon values #1 David Guest   Posts: n/a how do i pick the k and epsilon values to use for an aerofoil - transonic turbulent. all i know is the reynold number and the mach number and the aerofoil dimensions. thanks

 March 4, 2001, 21:15 Re: K - Epsilon values #2 John C. Chien Guest   Posts: n/a (1). You don't just pick k and epsilon, you have to define the free stream condition before you can solve your problem. (2). The turbulence kinetic energy can be measured, so, you must set it to the measured condition you are trying to simulate. Otherwise, you just define it for your problem. (say a few percent of the free stream velocity. since what you don't know can hurt you, I suggest that you review the turbulence modeling with two-equation models first.) (3). The epsilon part is more complicated to understand, so, you need to read the user's guide first, there must be a formula you can use. Sometimes, it is related to the length scale you select. Since everyone is doing his own thing these days, I am not sure what is used in the code. (4). Talk to the support engineer, or define your own numbers and check the results. Part of it, like k is real, part of it ,like epsilon is not. So, you have to be careful in defining these numbers. In other words, sometimes the results are sensitive to these values.

 March 5, 2001, 10:31 Re: K - Epsilon values #3 Flav Guest   Posts: n/a It depends on the experimental data you have. If you don't have values for k and epsilon, remember that you can specify the turbulence data by means of "intensity and length scale" instead of "k and epsilon".

 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 nedved OpenFOAM Running, Solving & CFD 13 November 4, 2013 15:13 Gearb0x OpenFOAM Running, Solving & CFD 2 May 20, 2010 12:36 nikhiljain.iitk FLUENT 0 March 12, 2010 07:06 nedved OpenFOAM Running, Solving & CFD 1 November 25, 2008 21:21 Adrian FLUENT 3 September 26, 2008 11:16

All times are GMT -4. The time now is 10:22.