I think it would be best to try out - both with and without enhanced wall treatment so that you can conclusively establish the answer for your case and also to understand your case better. The effect of the wall treatment and capturing the turbulence would really depend on the mesh density you have used near the wall. The effect is also determined by the kind of physics/geometry/ situation you are simulating.

I feel that, while moving towards higher velocities, beyond a point, the boundary layer may not have the time to develop/affect the flow and thus wall treatment may not affect the solution. However, this would seem more applicable for a streamlined body and only for sufficiently high flow velocity, which may vary for each situation.

I look forward to reading the contributions and opinions of experts on this.

Thank you Shreyas Ragavan, I also tried the same way, mine is a streamline body, actually it does not effect much, and I believe at high Re it may vanish also..........

At very high Reynold's number (~10^7 or ~10^8) though the effect seems to be negligible but still it add something to flow under consideration . So you should consider it.

This case is interesting. At a glance one will be tempted to say that there is no need to consider the effect at the walls at very high Re number, but one needs to ask what type of fluid? and what is the nature of the wall? Is there any form of interaction between the wall and the fluid? these questions need to be answered before taking any decision.

Hey friends I have tried both ways, my problem is n slender body, and fluid is water, not much difference

is seen.

HI

As this is HIght turbulent flow your seperation will be delayed furthur, more over the working fluid is water so your viscous forces at the wall will not be so dominent.Using standard k-epsilon with a Y+ between 30 to 300 will resolve your flow features pretty well,again if you want resolve your wall well below y+

There are some important effect on the wall, even at high Reynold number, that are e.g. particle deposition and phase separation; this effect may be taken into account, depending on the fluid! Another very important effect is the friction against wall, that may produce heat or affect the momentum of the fluid. This need a carefull evaluation befere assuming 'ok it may be neglected'.

Very useful and precise comments - Srinivas Rao and Giordano Montegrossi , thank you, I have experienced and read about both, it seems to me that my flow is not that complex and is a antisymmetric one with Length/Dia>8, a slender body and I also found that EWT do not effect much.