Turbulence & Laminar Flow: Internal Flow in pipe CFD Simulation, Laminar Vs. Turbulent Flow

What You'll Build

This lesson walks you through one of the most fundamental and important comparisons in all of CFD: laminar versus turbulent flow inside a pipe. Rather than simulating a single case, you'll run the same geometry three times — once as laminar flow, once with the k-ε RNG turbulence model, and once with the k-ω standard model — and compare the results side by side.

Understanding when a flow is laminar (smooth, ordered layers) versus turbulent (chaotic, vortex-dominated), and which turbulence model to apply, is the single most important modeling decision in CFD. This lesson gives you that intuition directly.

What You'll Learn

• The physical difference between laminar and turbulent flow, and how Reynolds number vs. critical Reynolds number determines the regime

• How inlet velocity drives Reynolds number — using 0.0176 m/s for laminar and 0.334 m/s for turbulent cases

• How to design a symmetric 3-D half-pipe geometry (semi-cylinder, radius 0.015 m, length 1 m) in Design Modeler to cut computation in half

• How to generate an efficient structured mesh (~23,120 elements)

• When to choose k-ε RNG (curved geometries, transient flows, HVAC problems) versus k-ω standard (adverse pressure gradients, separation, swirling flows, aerodynamics)

• How to set up a pressure-based steady solver with SIMPLE coupling and second-order discretization

• How to post-process and compare pressure, velocity, and turbulent kinetic energy contours across all three regimes on the pipe's symmetry plane

• How to extract velocity and pressure plots along the central axis to quantify the differences between the two turbulence models

Why It Matters

Every CFD engineer must answer "is my flow laminar or turbulent, and which model do I use?" on every project. This lesson builds that judgment from the ground up — making it one of the most valuable foundational skills in your entire CFD journey.