hi all,

I am running some unsteady calculations. Flow is buoyancy driven. Time step is 1 sec. I am using std k epsilon with enhanced wall.

I am checking on y+ from time to time and I see that it is hovering around 2.5 to 4,5 etc. At one occasion though it went upto 10. ---- IS THAT OK? OR IS IT NECESSARY TO KEEP Y+ AROUND 1 all the time?

you should keep you y+ value at 1-4 but in my opinion a value of 10 is very high.

regards

zachi!

Using the Enhanced wall treatment as wall function at least needs to have about 6, 7 layer grids inside the viscous sublayer. The recommandation of Fluent user guide is that yplus should about 1 but it also says that it can be also about 4 or 5. I was working on enhanced wall treatment for some month and I published a paper which showed that using EWT option gives acceptable results for heat transfer of impinging jets. any in a complex flow and stagnation area of this kind of flow the y plus had to be equal or less than one. I recommand to solve your problem with different size of grid and validate your results with different y pluses.