[_helix22_]

Hi everyone,

I am quite new to Openfoam, and multiphase flows. I am currently working on a research project concerning turbulent, gravity driven, open channel flows, at relatively low Reynolds numbers (around 10.000) using InterFoam (and a few interFoam derivatives) and a kOmegaSST Turbulence model. The simulations (currently in 2D) work nicely, however the velocity profile is a little odd. If I plot U+ over Y+ (so a classic law-of the wall kind of plot) and compare it to a closed channel at the same ReTau, the velocity levels of around halfway to the surface, and overall reaches a maximum U+ which is around 20% lower than the closed channel. We already discussed this in our lab and are a little confused by this result. There seem to be a few remarks in literature concerning issues with Predictions at the interface, but very little data (neither numerical nor experimental) on relatively low Reynolds open channel flows. Hence we are unsure whether this may actually be a physical phenomenon or a modelling issue.

If anyone has experienced anything similar, any ideas/input would be great help...

All the best and thanks in advance,
Alex