i have split rectangle with submerged cylindre where comes the flow , then i have got two cylindres,i haven't any problem with the top cylindre , my probleme is situated in the wall of the submerged cylindre , fluent create wall shadow and wall in the submerged cylindre, how to eliminate wall shadow. and if wall shadow affect the results? best regards

wall shadow will be created by fluent, when a wall surface faces two different fluid volumes on both the sides of the surface. Fluent creates shadow when ever a surface faces two different fluid volumes on both the sides of the surface, because the fluid properties wont be the same in the case of different fluids and the wall shear stress on both the sides of the surface wont be the same because of two different fluids. This wall shadow disappears, when we make the wall surface to interior boundary condition.

you told me to put wall surface to interior but sir when i do this operation the wall surface disappears. this surface exists in my geometry i haven' a different fluid, the problem is created (wall shadow) because the surface separates the fluid . best regards

If there's supposed to be a wall there, then the wall-shadow is not a problem. The wall shadow represents one side of the wall and the original wall BC represents the other side of the wall... Most of the BCs in Fluent are single sided, meaning they can only handle a fluid volume on one side. The wall BC is like this, so to deal with it, if Fluent finds a volume on both sides of a wall, it will create a wall-shadow BC. This will be no different than if you had a double-sided wall.

There's more information on wall-shadows on the forum. If you need more info, try searching the forum.

Best of luck, Jason

Hi Paul!

If physically a wall exists in your fluid domain, then it wont be a problem, even the wall-shadow has been created.

Give the surface wall boundary condition to the wall and to the wall-shadow..it wont create any issue in the analysis.

[satishverma]

While generating a wall (which is in the shape of 8, my intention is to rotate
this shape inside the duct having air as a fluid)
there automatically a wall shadow is generated in the fluent, which is not desired.
Sir! if you have any idea to resolve this problem please share it i will be very thankful.