What is the isotropy of turbulence ?

in brief: turbulence = fluctuations.

If you assume isotrophic turbulence, you assume these fluctuations are the same in all directions, and that the effect is the same in all directions.

This assumption is not always correct. In wall bounded flows or swirling flows for example, the effects of turbulence are not isotrophic.

hope this helps

Laika, still orbiting

Hi Laika,

Is the Ke-turbulence model based on the isotropic assumption? If so does this mean it can not be used in swirling flows or internal flows?

Thanks

Mark.

Indeed, the basic ke-models are isotrophic, and that's one of the main disadvantages. Fortunately, Fluent has also the RNG variant available: that's the one to use with swirling flows. The RNG variant is not isotrophic and even has a 'swirl dominated flow' option.

greetings,

Laika, still orbiting