Equations of k-Epsilon Model

MissCFD · March 29, 2015, 13:57

Hello,

In the theory guide, it is noted that the term 3* $\mu_{t}$ in Equation 2.25 (p. 85) for the turbulence production is based on the “frozen stress” assumption [54]. This prevents the values of Epsilon and k becoming too large through shocks, a situation that becomes progressively worse as the mesh is refined at shocks.

I don't understand this explanation. What is meant by ''frozen stress'' and what is the significance of ''shocks'' in this context ?

Thank you for your help

ghorrocks · March 29, 2015, 19:02

I am no expert in turbulence modelling - the manual has a reference for that statement so you will have to look up the reference.

But you should be aware that the shocks they are referring to are compressible flow shock waves.

March 29, 2015, 13:57	Equations of k-Epsilon Model	#1
MissCFD Senior Member Join Date: Aug 2014 Posts: 160 Rep Power: 12	Hello, In the theory guide, it is noted that the term 3* $\mu_{t}$ in Equation 2.25 (p. 85) for the turbulence production is based on the “frozen stress” assumption [54]. This prevents the values of Epsilon and k becoming too large through shocks, a situation that becomes progressively worse as the mesh is refined at shocks. I don't understand this explanation. What is meant by ''frozen stress'' and what is the significance of ''shocks'' in this context ? Thank you for your help

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Overflow Error in Multiphase Modelling with Two Continuous Fluids	ashtonJ	CFX	6	August 11, 2014 15:32
Multiphase Homogeneous Model equations	marcoymarc	CFX	3	July 3, 2013 20:11
An error has occurred in cfx5solve:	volo87	CFX	5	June 14, 2013 18:44
Jump in epsilon values near the wall : low re k-epsilon model	malaboss	OpenFOAM Verification & Validation	1	February 1, 2013 17:36
Reynolds transport, turbulence model, etc	Beginner	Main CFD Forum	1	January 7, 2009 06:36

March 29, 2015, 19:02		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,872 Rep Power: 144	I am no expert in turbulence modelling - the manual has a reference for that statement so you will have to look up the reference. But you should be aware that the shocks they are referring to are compressible flow shock waves.