[David81]

I am quite new to CFD and my question here may be a bit easy for you. But I am really struggling and your help are really appreciated.

I have came across a variable uvw which I really can't find a definition to it. I know that uv represents Reynolds stress, but not uvw at all.

Also, can someone briefly describe what is our purpose of calculating the root mean square of a variable, like streamwise velocity fluctuation? Thank you in advance for your kind help.

[Svetlana]

Regarding the last question, mean of a fluctuation is zero, so mean of its square is used instead. This allows to quantify the magnitude of the fluctuation.

[FMDenaro]

Originally Posted by David81

I am quite new to CFD and my question here may be a bit easy for you. But I am really struggling and your help are really appreciated.

I have came across a variable uvw which I really can't find a definition to it. I know that uv represents Reynolds stress, but not uvw at all.

Also, can someone briefly describe what is our purpose of calculating the root mean square of a variable, like streamwise velocity fluctuation? Thank you in advance for your kind help.

It is a component of the third order tensor vvv ...

[David81]

Thank you very much Светлана. And we then take the root of the mean square to cancel out the effect of previously squaring it, am I understanding it correctly?

[David81]

Hi FMDenaro, thank you very much. May I ask abit more? I am still confused as to what this uvw means. What does it actually represents? Thank you.

[FMDenaro]

Originally Posted by David81

Hi FMDenaro, thank you very much. May I ask abit more? I am still confused as to what this uvw means. What does it actually represents? Thank you.

For example, in turbulence modelling you could construct the evolution equation for the components of the Reynolds stress tensor. Thus, you could read that as the velocity component u transporting the variable (vw) in the convective flux

[David81]

Thank you very much FMDenaro.