[feitoudaer]

Hi a basic question in turbulence.
what does the word "homogeneous" exactly mean for turbulence? please explain in both physical and mathematical ways.
for example, take the turbulent-kinetic-energy transport equation as an example, if the flow is homogeneous turbulence, then in the equation how to judge which term can be deleted?
Many thanks.

[thecfduser]

Hi
Homogeanous turbulence means that turbulence is invariant by tanslation.
U have the same turbulence prprieties anyway in the flow (so u must be at high Re and far from walls). Urms in point X1 is equal to Urms point X2. The same for Vrms....but Urms is not necesseraly equal to Vrms
Isotropic turbulence means invariance by rotation. The rms fluctations have the same strength in all directions. Urms is equal to Vrms in in a point. But Urms in X1 is not necessarly equal to Urms in X2...
If both conditions are available, u can use Kolomogorov theory.

If the turbuelce is homogeanous, u will not need the equation of transport of k: k will be the same anywhere. (considering of course an adequate time averaging, because turbulence can never be instantaneously homogeanous)

Hope that u understood me

[hasanifte]

Does the production term equal zero? in homogeneous turbulence why or why not?

[FMDenaro]

Originally Posted by hasanifte

Does the production term equal zero? in homogeneous turbulence why or why not?

if you consider the case of three-periodic box, the turbulence is homogeous and isotropic and if the flow is not substained by a production of energy it simply decay. If you add a suitable production the energy equilibrium is obtained. As you see, that does not change the homogeneity of the flow