Can we model k epsilon without wall function?

parthigcar · March 14, 2022, 21:50

I am modelling a dissimilar heated plate with a small 2D domain (200 mm x 200 mm). I wanted to compare different turbulent models for my problem. But for the k epsilon model, the first layer height (estimated from online y+ calculators) is coming around 0.06 m (for y+ of 30), which is too much coarse mesh for my domain. Is it possible to go with a fully resolved approach for k epsilon model? How we can do it in OpenFoam? I can resolve the mesh for y+ ~1, as the domain is small and 2D.

piu58 · March 15, 2022, 11:48

k-e is a high Reynold approach. Therefore it is easy holding y+ between 30 andd 300, as recommended.

If you have such a large y+, you don't have a high Reynold situation.

You don't need a wall function if you have y+ in the near of 1, because your simulation resolves the viscous sublayer..

parthigcar · March 15, 2022, 21:31

Thank you..!!

March 14, 2022, 21:50	Can we model k epsilon without wall function?	#1
parthigcar New Member parth Join Date: Feb 2020 Posts: 23 Rep Power: 6	I am modelling a dissimilar heated plate with a small 2D domain (200 mm x 200 mm). I wanted to compare different turbulent models for my problem. But for the k epsilon model, the first layer height (estimated from online y+ calculators) is coming around 0.06 m (for y+ of 30), which is too much coarse mesh for my domain. Is it possible to go with a fully resolved approach for k epsilon model? How we can do it in OpenFoam? I can resolve the mesh for y+ ~1, as the domain is small and 2D.

March 15, 2022, 11:48		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	k-e is a high Reynold approach. Therefore it is easy holding y+ between 30 andd 300, as recommended. If you have such a large y+, you don't have a high Reynold situation. You don't need a wall function if you have y+ in the near of 1, because your simulation resolves the viscous sublayer.. parthigcar likes this. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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March 15, 2022, 21:31		#3
parthigcar New Member parth Join Date: Feb 2020 Posts: 23 Rep Power: 6	Thank you..!!