Turbulence boundary conditions for CFD simulations

One of the most important boundary parameters in CFD simulations is determining the turbulence conditions at an inlet. Turbulence intensity for fully developed flows in conduits can be estimated empircally using the follwing forumula:

Turbulence Intensity

The length scale can also be calculated empirically depending on the type of problem in questions. For wall bounded flows with turbulent a boundary layer at the inlet, users may choose Intensity and Length Scale as their turbulence parameters:

length scale

Kronecker delta: is the boundary layer thickness

For fully developed flows in enclosed conduits the length scale is proportional to the hydraulic diameter:


Length scale in enclosed conduits

 

 

 

Calculator

Hydraulic Diameter:

     Length Scale - fully developed flow in enclosed conduit