Use of turbulent intensity and the turbulence length scale?

gerie · December 1, 2017, 10:29

Dear all,
Can somebody help me what is the use of turbulent intensity and the turbulence length scale in turbulence model? why do we put them as input data when we are making turbulence model simulation?Many thanks for your help!
kind regard,
Gerie

LuckyTran · December 1, 2017, 14:49

Google is your friend.

https://www.cfd-online.com/Wiki/Turbulence_intensity
https://www.cfd-online.com/Wiki/Turb...kinetic_energy
https://en.wikipedia.org/wiki/Turbulence_kinetic_energy

In boundary value problems you specify the governing equations, provide boundary conditions, and then solve for the solution inside the domain,

Hence in addition to pressure, velocity, temperature and so on at boundaries, you also must provide the turbulence (but according to the turbulence variables in your model). If you are using k-epsilon model then you need to specify k and epsilon at boundaries. If you are using k-omega model then you need to specify k and omega at boundaries. etc. Fluent has a feature that allows you to specify instead the turbulence intensity and length scale as a convenience option because people generally have a better feel for intensity and length scale (as opposed to k & epsilon or k & omega).

December 1, 2017, 10:29	Use of turbulent intensity and the turbulence length scale?	#1
gerie New Member Gebregziabher Join Date: May 2017 Location: Berlin Posts: 7 Rep Power: 9	Dear all, Can somebody help me what is the use of turbulent intensity and the turbulence length scale in turbulence model? why do we put them as input data when we are making turbulence model simulation?Many thanks for your help! kind regard, Gerie

December 1, 2017, 14:49		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	Google is your friend. https://www.cfd-online.com/Wiki/Turbulence_intensity https://www.cfd-online.com/Wiki/Turb...kinetic_energy https://en.wikipedia.org/wiki/Turbulence_kinetic_energy In boundary value problems you specify the governing equations, provide boundary conditions, and then solve for the solution inside the domain, Hence in addition to pressure, velocity, temperature and so on at boundaries, you also must provide the turbulence (but according to the turbulence variables in your model). If you are using k-epsilon model then you need to specify k and epsilon at boundaries. If you are using k-omega model then you need to specify k and omega at boundaries. etc. Fluent has a feature that allows you to specify instead the turbulence intensity and length scale as a convenience option because people generally have a better feel for intensity and length scale (as opposed to k & epsilon or k & omega).