Why is the freestream sensitivity of the k-omega model a handicap?

Fole · April 24, 2017, 10:37

Hello to all,

Why is the freestream sensitivity of the k-omega model a handicap?

I have that question after reading the book of Wilcox "Turbulence modeling for CFD" and after thinking about its comments on the behavior of the standard k-omega when the flow is in the transitional regime. It is noted that this sensitivity is beneficial for capturing the dependence of transition on flow free stream turbulence.

Mismatches are welcome!

Thanks for reading,
Fole.

LuckyTran · April 25, 2017, 00:09

Wilcox devotes a lot of attention to this topic in his book.

To be more specific, the k-omega model is sensitive to the freestream boundary condition for omega. The problem is more-or-less self stated. The solution depends on what you specify as the freestream boundary condition for omega. This means the k-omega model is a somewhat failure as a model because it depends on the user input! I.e. for each individual problem, you must determine beforehand the correct freestream value for omega, which means you cannot apply the k-omega model to new problems, you can only apply it to problems in which you already know the solution, which is not what a model is for.

April 24, 2017, 10:37	Why is the freestream sensitivity of the k-omega model a handicap?	#1
Fole New Member Ovid Join Date: Oct 2016 Location: Spain Posts: 28 Rep Power: 10	Hello to all, Why is the freestream sensitivity of the k-omega model a handicap? I have that question after reading the book of Wilcox "Turbulence modeling for CFD" and after thinking about its comments on the behavior of the standard k-omega when the flow is in the transitional regime. It is noted that this sensitivity is beneficial for capturing the dependence of transition on flow free stream turbulence. Mismatches are welcome! Thanks for reading, Fole.

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April 25, 2017, 00:09		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,754 Rep Power: 66	Wilcox devotes a lot of attention to this topic in his book. To be more specific, the k-omega model is sensitive to the freestream boundary condition for omega. The problem is more-or-less self stated. The solution depends on what you specify as the freestream boundary condition for omega. This means the k-omega model is a somewhat failure as a model because it depends on the user input! I.e. for each individual problem, you must determine beforehand the correct freestream value for omega, which means you cannot apply the k-omega model to new problems, you can only apply it to problems in which you already know the solution, which is not what a model is for.