Hi,

I have a problem with creating a boundary layer in Gambit. Imagine a horizontal pipe of large diameter suddenly contracting to a smaller diamter. How do I go about attaching a boundary layer to the vertical wall that forms the contraction. I have to model this in 3d as the rest of the geometry is quite complex - it's easy to do this in 2D but I can't figure it out in 3D.

Any help would be much appreciated.

Thanks,

Mike

Hi Mike,

Imagine a pipe 200mm in length and 30mm in dia extruded in the positive Z direction and a pipe with 100mm length and 10mm in dia extruded in the negative z direction.

with a single volume of the 2 pipes.open the boundary layer option and the set the a value and then select faces instead of edges. select the outer face.

this means that your prism elements faces are perpendicular to the flow.

Hope these are helpful.

Regards

Rajit

Thanks Rajit,

I think the single volume is where things may have been going wrong.

Regards,

Mike