Non-Newtonian: Eulerian Flow Between 2 Concentric Cylinders

What You'll Build

This lesson walks you through a CFD simulation of two-phase non-Newtonian flow between two concentric cylinders — a benchmark geometry used across drilling engineering, polymer processing, biomedical devices, and food technology. Unlike Newtonian fluids (water, air), non-Newtonian fluids change their viscosity in response to applied shear — and capturing that behavior correctly is critical for accurate predictions.

In this project, you'll model a Power-Law non-Newtonian base fluid (k = 0.021, n = 0.75) flowing through an annular channel with a rotating inner cylinder, while a denser soluble secondary phase travels through it using the Eulerian multiphase model.

What You'll Learn

• The difference between Newtonian and non-Newtonian fluids, and when each model applies

• How to design a 3-D annular geometry (1 m length, 0.0225 m inner diameter, 0.03125 m outer diameter) in Design Modeler

• How to generate a structured mesh (~1.4 million elements) appropriate for annular and rotating-flow problems

• How to configure the Power-Law viscosity model in Fluent — setting consistency index k, flow behavior index n, and clamping minimum/maximum viscosity bounds

• How to set up the Eulerian multiphase model with two implicit phases, including phase-specific densities, viscosities, and inlet volume fractions

• How to apply a rotating wall boundary condition (100 rpm on the inner cylinder) — essential for any Taylor–Couette-type analysis

• How to choose Coupled pressure–velocity coupling with PRESTO! pressure discretization for rotating multiphase flows

• How to post-process 2-D and 3-D contours of pressure, velocity, and volume fraction for both phases

Why It Matters

The same workflow underpins drilling mud analysis, polymer extrusion, blood flow in narrow vessels, paint coating, and food processing — anywhere viscosity isn't constant. Mastering this case unlocks a wide family of rheologically complex industrial problems.