Free Engineering Simulation Tutorial - Opensource Software & Simulation Guides

You set up a perfect mesh, chose k-ω SST, hit run — and your turbulence quietly dies before the flow even reaches the object. The cause is almost always the same: bad turbulence inlet boundary conditions. Two-equation models like k-ε and k-ω SST need starting values for turbulence at the inlet, but those values ( k , ε , ω ) are hard to guess directly. The trick every CFD engineer uses is to specify two intuitive quantities instead — turbulence intensity (I) and length scale (ℓ) — and convert them. This guide gives you a free, validated calculator that does exactly that, plus the theory behind every number. Figure 1. At a CFD inlet you specify turbulence intensity (I) and length scale (ℓ), and the solver converts them into k, ε and ω — the quantities the turbulence model actually solves. Table of Contents The Turbulence Inlet BC Calculator Why Turbulence Inlet Conditions Matter Turbulence Intensity (I) Turbulence Length Scale (ℓ) The Conv...