How do i calculate boundary conditions for turbulence at the inlet and outlets? I have the reynolds numbers at these boundaries, and the diameters for the pipes.

Reading the user guide, I am assuming i use the turbulence intensity and length scale to define the turbuence. Does anyone have some good approximating formula's for these parameters?

My model involves a compressible gas flow at 6000kPa (within a natural gas transmission pipeline).

Thanks.

Intensity (Refer Fluent manual for calculating turbulence intensity -> http://www.fluentusers.com/fluent/do...e180.htm#26619) and Hydraulic diameter (= diameter of pipe for a cylinder even if modeled in 2D).

it is difficult to calculate them accurately. a thumb rule says that moderate intensity of 5% should be used. at the upper range, it can be 15-20%. i am not sure about length scale range.

Swarup.