hello all

thanks a lot for your attention. I need (long) time to learn !... :>

I'd like to ask again about turbulent eddie :

1. As Jonas & Prabhu said, turbulent eddie is small & vortex can be a large scale structure. I read that there is large scale eddie (contained most kinetic energy) how about that? Can we see the turbulent eddie?

2. I saw the paper about simulation of fluid flow in combustion engine chamber. There were rotasional structure called swirl and tumble. Are these vortex or turbulent eddie (the flow was turbulent) ?

that's all thanks again for the answers

regards

sakti

1). If you take a long-time exposure photo of a turbulent flow , you get sort-of time-averaged flow picture,that is the mean flow picture. 2). If you move the camera at the mean flow speed, those turbulent eddie moving at the mean flow speed will be stationary, relative to the camera, and you will be able to see the structure of these eddie. 3). If you move the camera at a lower speed, you will see only those eddie moving at this lower speed. You will not be able to see the structure of those eddie moving at the mean flow speed at this lower camera speed. 4). Swirl and tumble motion are mean flow motion, which is equivalent to the long-time exposure photo of the flow in a combustion chamber. 5). Swirl and tumble ( rotational motion in two different axis ) are used in the IC engine design to improve mixing and combustion efficiency.